Historic, Archive Document Do not assume content reflects current scientific knowledge, policies, or practices. PROCEEDINGS OF THE 34TH SOUTHERN PASTURE AND FORAGE CROP IMPROVEMENT CONFERENCE Auburn University Auburn, Alabama April 12-14, 1977 This publication is reproduced from camera-ready copy supplied by the authors. The views of participants are their own and do not necessarily reflect the views of the U.S. Department of Agriculture. Mention of trade names does not constitute a guarantee or warranty of products by the U.S. Department of Agriculture or an endorsement by the Department over other products not mentioned. Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE July 1977 This publication is available from Homer D. Wells Agricultural Research Service Tifton, GA 31794 CONTENTS Page Forages in Alabama, by Donald M. Ball 1 Forage breeding highlights at Auburn (Ala.) Agricultural Experiment Station, by Wiley Johnson.. 5 Nematodes and forages, by C. S. Hoveland, R. L. Haaland, E. D. Donnelly, and R. Rodriguez-Kabana 7 Forage-fed beef in Alabama, by R. R. Harris 11 Recycling animal waste on forages, by T. A. McCaskey 13 Grass roots as a tool for penetrating soil hardpans and increasing crop yields, by Charles B. Elkins, Ronald L. Haaland, and Carl S. Hoveland.. 21 Anti-quality research on forages, by R. L. Haaland, E. D. Donnelly, C. B. Elkins, and C. S. Hoveland 27 Systems for backgrounding cattle, by H. W. Essig 29 Producing slaughter beef by supplementing pasture, by M. B. Wise 36 Finishing slaughter cattle with grass and grain, by John C. Carpenter, Jr. 43 Use of limited grain for finishing steers on pasture, by Maurice L. Ray and A. E. Spooner 47 Control of internal parasites in animals on pastures, by H. Ciordia 49 Current status of infrared reflectance, by J. S. Shenk and R. F. Barnes... 57 Breeding stocks available at regional plant introduction stations (abstract), by W. R. Langford 63 Population improvement by recurrent restricted phenotypic selection, by Glenn W. Burton 64 Identifying virus resistance in white clover by applying strong selec- tion pressure. I. Technology, by 0. W. Barnett and P. B. Gibson 67 Identifying virus resistance in white clover by applying strong selec- tion pressure. II. Screening program, by P. B. Gibson and 0. W. Barnett 74 The application of the coefficient of inbreeding to forage breeding methods, by Thad H. Busbice 80 Characteri zation of forage tissue by transmission and scanning electron microscopy, by Danny E. Akin, E. L. Robinson, and Donald Burdick 85 Tropical grass breeding and early generation testing with grazing animals, by K. H. Quesenberry, Rex L. Smith, S. C. Schank, and W. R. Ocumpaugh 100 Breeding apomictic grasses, by P. W. Voigt, B. L. Burson,and M. C. Engel ke 104 The Oklahoma bermudagrass breeding program: objectives and approaches, by C. M. Taliferro, W. L. Richardson, and R. M. Ahring 113 The proposed establishment of hay standards, by R. F. Barnes, D. A. Rohweder, and N. Jorgensen 120 Southern forages in the new hay standards, by John E. Moore 129 Storage and preservation of forage, by J. Kenneth Evans 136 Poisonous plants in pastures and animal response, by Agee M. Wiggins 139 Pasture weed problems and approaches used in Mississippi, by Vance H. Watson and Hiram D. Palmertree 143 Effects of grazing management on a smutgrass-bahi agrass-whi te clover sward, by William R. Ocumpaugh 148 Weed problems in Alabama pastures, by C. S. Hoveland 150 i Monensi n--what , how and potential on pasture, by Gerald W. Horn .151 Importance of ruminal protein degradation on amino acid availability, by H. E. Amos, J. J. Evans, and D. Burdick 157 Weed problems in Texas pastures, by Gerald W. Evers 165 Quality of legume inoculants and how it affects clover production in the South, by Kenneth L. Smith 166 SPFCIC Extension Work Group Summary of Five Minute Reports by States, by Donal d M. Ball 170 Contri butors 172 FORAGES IN ALABAMA By Donald M. Ball It’s my pleasure to welcome you to Alabama and to have the opportunity to tell you a little about forage production here. The first thing I'd like to tell you is that forages are an important agricultural commodity in Alabama. As you know, it's difficult to estimate the value of forages since they're not sold directly as other crops are. However, an indication of their importance in Alabama is the fact that our beef and dairy industries gross well over 200 million dollars annually. Of course, forages also supplement the diets of other farm animals, they have conservation value, etc. In short, there Is no question but that forages have a tremendous impact on Alabama's economy. Forages are also important from the standpoint that they occupy a signifi- cant portion of Alabama's land area. We estimate that we currently have over four million acres of improved pasture and other forage crops - that's about 5 5% of the non-forest ed agricultural land In the state. If we included range- land, this figure would be considerably higher. Although time won't permit me to describe in detail the various environ- ments we have for growing forages in various parts of the state, I can assure you that there are wide variations in soils, and there are also considerable variations in rainfall and temperature in various parts of the state. Not surprisingly then, there are many different forage species which are adapted to be grown in Alabama. Perhaps the most meaningful way to quickly orient you to Alabama agricul- ture is to describe the various agricultural regions of the state. These regional classifications to which I'll refer are based partially on soils and climate, partially on topography, and partially on agricultural land use. In the north central part of the state, we have what we refer to as our Limestone Valley or Tennessee Valley region. The soils in this area are pre- dominantly red clay loams. Most of the land is open, and it's an area of intensive row-cropping. Over half the state's cotton Is produced in the Lime- stone Valley area. Corn and soybeans are also important. Our Sand Mountain region is in the northeastern part of the state, and as the name implies, there is some rugged terrain in this area. Many plateau areas also exist, however, which contain highly responsive fine sandy loam soils. Corn, poultry, and various vegetable crops are important in this region. Many of our dairy producers are located in this area also. 1 In the east-central part of the state Is an area of rolling or rugged terrain which we call our Piedmont area. This section, which mostly contains red clay loam soils, at one time supported a large cotton acreage. Unfortu- nately, much erosion took place during this period of row-cropping. In the past two decades, much of the Piedmont area has been returned to woodlands or 1 put into pasture. si :?( lie The Upper Coastal Plain stretches from east to west across the central and into the northwestern parts of Alabama, and is an area in which timber is an important commodity. Most farmland in this area is either along streams or on rolling ridge tops. There is a diversity of agricultural interests in the region. p; o- to ar tin The Black Belt is a unique area stretching from east to west across the state which contains many montmorillonitic soils. These vary from being red, acid clays to being black, calcareous prairie soils. This is the area of the greatest beef cattle density in the state. Soybeans are also important in the Black Belt. The Wiregrass area in the southeastern corner of Alabama contains many deep, sandy soils, and is an area of much row-crop activity. Peanuts are the main cash crop, but corn and swine are also important. 13 11 St fo fu PJ The area in southwest Alabama which we refer to as our Lower Coastal Plaii is much like the Wiregrass area as far as soils and climate are concerned, but farming is not as intensive in this area. Much of the western part of this area is used for timber production, although soybeans, corn and beef cattle are also important. lo of C( ii Last but not least is our Gulf Coast area. This is an area of good farm- , land and the most intensive agricultural production in the state. Double- cropping is extensive in this region, and the main agricultural enterprises are horticultural crops, grain crops, and beef cattle. Now that you have in mind the main agricultural areas of the state, let’s consider the main forage -■ species used in Alabama. i « i 11 The forage species of which there is more acres than any other in Alabama is tall fesue - most of which is in the northern half of the state. We esti- mate that we have around one million acres of tall fescue, and essentially all of this is the variety 'Kentucky 31' • Varieties which are better adapted to the southern half of the state would be useful. i We also have around 900,000 acres of bahiagrass. Although bahiagrass was only introduced into Alabama a little over two decades ago, it is now by far the predominant pasture species in the southern half of the state. Most of our bahiagrass acreage is the variety ’Pensacola’ although 'Argentine' is increasing in popularity in the southern third of the state. 2 Bermudagrass is also an important forage species used both for grazing and hay. We estimate that we have around 650,000 acres, of which around 350.000 acres is 'Coastal.' There is a tremendous amount of interest among producers in new bermudagrass varieties and, although some varieties can' only be grown in some areas, bermudagrass of one variety or another can be grown in every county in the state. Another important perennial grass species is dallisgrass. Although dallis- grass generally doesn't yield as much as other warm-season perennials, it tends to compensate for this in that the forage is relatively good quality. We have around 400,000 acres of dallisgrass - most of this is in the Black Belt, al- though it can be grown in other areas of central and north Alabama. Johnsongrass is also grown primarily in the Black Belt and is used pri- marily for hay production. Johnsongrass makes very good quality hay if han- dled properly. We estimate we have around 100,000 acres of this species. Orchardgrass is grown almost exclusively in the northern third of the state. Although we appreciate the relatively high quality of orchardgrass forage, we have problems with persistence - this is particularly true the further south one goes in the state. Orchardgrass is frequently "crowded out" by tall fescue and we only have around 25,000 acres in which it is the pre- dominant species. As far as perennial legumes are concerned, white clover is certainly one of our most valuable species. Ladino is the most productive type, and '.Regal' is the most popular variety. We estimate we have around 100,000 acres which contain a significant amount of white clover, and in areas where it's grown, it is almost always used as a companion species to either fescue, orchardgrass, or dallisgrass. Another important perennial legume is sericea lespedeza. Most of our sericea acreage is on rolling or hilly land in the north and central parts of the state, and we have around 180,000 acres devoted to this species. Since the release of the improved varieties 'Serala' and 'interstate,' there has been renewed interest in growing sericea in Alabama. We currently have only a few thousand acres of alfalfa. Most of this is either in the Limestone Valley area or on the high pH Black Belt soils. There is a considerable amount of interest in growing alfalfa, however, and it seems likely that the acreage will increase in the next few years. Although we do not have any appreciable acreage of summer annual legumes, we do have an estimated 175,000 acres of summer annual grasses. Most of this is planted to either sorghum-sudan hybrids or pearlmillet. We only have around 15.000 acres of silage corn, and less than 5,000 acres of silage sorghum. Most of our silage is used in dairy operations. 3 I've saved for last the area of forage production which is currently creating the greatest amount of enthusiasm among producers. I'm referring to our winter annual forage species. When we talk about winter annual forages in Alabama, we’re basically talking about some combination of three types of plants: (l) small grain - usually either rye or wheat; (2) annual ryegrass; and (3) annual clover - usually either crimson or arrowleaf clovers. We estimate that we have some 600,000 acres devoted to winter annual grazing crops, and the acreage is in- creasing. These species are particularly important to us, because they give the Alabama producer the advantage of being able to provide high-quality grazing during even some of the coldest months of the year. In Alabama, winter annuals are mostly used in stocker calf and dairy programs. Mixtures of winter annuals provide high-quality grazing over an extended period of time. The release of arrowleaf clover has been particularly important for Alabama pro- ducers because it allows extension of the winter grazing period to late May or June. I certainly don’t want to mislead you - we have our share of problems with forage production in Alabama. One big problem is weed control. Another prob- lem is inadequate fertilization and liming. Still another problem is that many producers show little concern about the quality of stored forages. We also have other problems which we are trying to overcome. I'd like to conclude this review of forage production in Alabama by dis- cussing the most impressive part of the Alabama forage picture. I'm referring to the fact that Alabama has tremendous unrealized forage production poten- tial. We have potential for increasing the productivity of existing forage crop acreage, and we also have much potential for expansion of acreage. At the present, approximately 65^ of Alabama's land area is in woodlands. It's reasonable to believe that eventually much of this woodland, most of which is not suitable for row-crop production, will be utilized for forage production. In summary, because we have a mild climate and good rainfall which are conducive to the growth of forages throughout most of the year, because we have land available for expansion of forage crop acreage, and because we have a pro- gressive forage research program here at Auburn University, we're optimistic about the future of forage production in Alabama! 4 FORAGE BREEDING HIGHLIGHTS AT AUBURN (ALA.) AGRICULTURAL EXPERIMENT STATION By Wiley Johnson Sericea Following the development of low tannin sericea germplasm (Beltsville 23-864) by USDA personnel at Beltsville, Md., sericea with a desirable plant type and low tannin content was developed at Auburn by Dr. E. D. Donnelly. This was accomplished using the backcross method with normal high tannin sericea as the recurrent parent and with progeny testing and selection for low tannin following each backcross. The resulting low tannin sericea was found to be extremely susceptible to Rhizoctonia. Extensive testing and selection, however, has demonstrated that susceptibility to Rhizoctonia was largely a case of close linkage with low tannin and not pleitropy. Linkage has been broken and Rhizoctonia resistant, low tannin, vigorous selections have been identified . Extensive cooperative research involving Dr. Donnelly and Dr. Norman Minton of the USDA at Tifton, Ga. has been conducted to develop sericea varieties resistant to root-knot nematodes. Two varieties, Serala 76 and Interstate 76, which have a high level of resistance to most common strains of root-knot nematodes have recently been released. Vetch Recent emphasis in vetch breeding has been to develop varieties com- bining the characteristics of hard seed, vigorous winter production, and cold hardiness. Selection in the advanced generations of interspecific hybrids of Vicia sat iva x V. cordata and V. sativa x V. serratif olia has resulted in the recent release of the following V_. sativa (common vetch) type varieties: Nova II, Cahaba White, Vantage and Emerald. Cool season perennial grasses The breeding projects on tall fescue and phalaris emphasize winter pro- duction and resistance to the root-pruning nematodes. Considerable variation within available germplasm in regard to these characteristics is evident and numerous selections have been made and are being further evaluated and re- combined for additional selection. Tall fescue is being selected for high Mg content especially under conditions of low soil 02* The objective of this project is to reduce the grass tetany potential of tall fescue. Nurseries of diverse orchardgrass germplasm have been established. Selection will be based upon persistence to extend the practical range of adaptation for this valuable forage species southward to include central Alabama . 5 Other forage legumes Alfalfa is unquestionably the most valuable forage legume in the United States. However in the lower South, persistence of a productive stand beyond the first harvest year is unusual. Alfalfa nurseries are established for evaluation and selection primarily for persistence. Recent introductions of birdsfoot trefoil from South America make available germplasm with the potential of yielding selections that are pro- ductive and persistent in Alabama. This material is being evaluated. Arrowleaf clover has been remarkably free of damaging pests. Recently some arrowleaf clover stands have been severely damaged by an unknown malady locally called "red-leaf disease". Isolations strongly implicate a Fusarium sp. fungus as a primary causal organism. Spaced plants have been inoculated to verify this relationship and to possibly select for resistance. The white clover breeding project emphasizes persistence. Selections within progeny of crosses among the parental clones of Regal for improved seed production are being made. 6 NEMATODES AND FORAGES By C. S. Hoveland, R. L. Haaland, E. D. Donnelly, and R. Rodriguez-Kabana Parasitic soil nematodes, known to cause serious losses in many row crops, have received relatively little attention from forage crop scientists. Serious work on nematodes must determine: (a) forage yield losses and the importance of nematodes on that forage crop species, (b) the particular nematode species attacking the plant, and (c) possibilities of lessening nematode losses by cultural methods, or nematicidal treatment, or breeding resistant cultivars. Research work in this area is tedious, time-consuming, expensive, and frustra- ting. Field experiments generally require 8 replications to deal with the extreme variability in soil nematode populations within an experimental area. Nematode populations are affected by soil temperature, moisture, availability of plant roots to feed upon, and the crop species grown previously. Screening techniques for developing nematode resistance or tolerance in forage species are often limited. Nematode resistance mechanisms and inheritance resistance mechanisms in most forage crops have not been elucidated. Effective nematode research on forage crops requires close cooperative work with a field-oriented nematologist . Finally, adequate numbers of technicians must be available to process and count nematodes in the large amount of soil and root samples generated in this type research. Poor seedling establishment, low yields, and lack of persistence are often a result of nematodes attacking roots of forage crops. Nematodes in the south- eastern USA have been shown to attack forage crop species such as orchardgrass and tall fescue (11), white clover (12), millet and sorghum-sudangrass (10) and perennial tropical grasses (2) . Some results of forage nematode research at Auburn are summarized in this paper. Sericea Lespedeza Evidence that nematodes severely damage sericea lespedeza (Lespedeza cuneata) was obtained in 1955 by Donnelly (3). Several species of root-knot nematode were identified as causing damage and sericea lines differed in sus- ceptibility (18) . Forage yields were as much as 57 times greater for resistant entries than for the susceptible check (14) . Resistance in two lines was caused by a single dominant gene while in another line a single dominant carried resistance but two genes were present in some individuals (1). Persistance and forage productivity of nematode-resistant lines have been superior (15), making prospects excellent for release of a sericea lespedeza cultivar adapted to sandy Coastal Plain soils where nematodes are a serious problem. Vetch ’Warrior' vetch (Vicia sativa) developed at Auburn, is resistant to three of the five important root-knot nematode species (16). In contrast, hairy vetch (Vicia villosa) is susceptible to all five of the nematode species. Fewer 7 nematode larvae penetrated roots of the resistant Warrior variety and most of those that did enter failed to develop (17). V. leganua and V. angustifolia are susceptible to all five root-knot nematode species (13). Hybrids of V. sativa and V. cordata are resistant to three root-knot nematode species. Cool Season Grasses Productivity of cool season perennial grasses can be sharply reduced by parasitic soil nematodes. In trials at three locations in Alabama, establish- ment-year forage yields were doubled for phalaris (Phalar is aquatica) and tall fescue (Festuca arundinacea) and increased 3^ times for orchardgrass (Dactylis glomerata) at the first harvest with control of soil nematodes (6). In another experiment with tall fescue and phalaris, the establishment-year yields were increased 40 to 50% with nematode control (7). Second-year yield differences were generally much greater than the first year. Tall fescue yields were doubled with methyl bromide soil treatment and increased 40% with carbofuran above that of untreated soil. Phalaris yields were increased 4^ times with methyl bromide and over 2^ times with carbofuran. Results indicate a cumula- tive effect of nematodes, and possibly fungi, in depressing forage yields dur- ing the second year. Autumn and early winter forage harvests of tall fescue on methyl bromide-treated soil were two to four times that of untreated soil. Phalaris had little or no autumn growth on untreated soil, a result of root pruning by nematodes. This restricted grass roots to a shallow layer of soil, preventing utilization of water and nutrients at greater depths. Stand losses of phalaris occurred on untreated soil during a severe autumn drought. The most important nematode species attacking the grasses were stunt (Tylenchorhynchus claytoni) , lance (Hoplolaimus galeatus) , and stubby root (Trichodorus christiei) (5, 7, 8, 9). Nematodes may interact with other orga- nisms, particularly Fusarium, Pythium, and Rhizoctonia to cause pathological effects on phalaris (G. R. Smith. 1977. The use of greenhouse screening tech- niques to detect and characterize a nematode-disease complex of Phalaris aquatica L. M.S. thesis. Auburn Univ.). Up to a 40% increase in autumn rye (Secale cereale) forage production has been obtained by soil application of carbofuran nematicide (9) . Ryegrass (Lolium mult if lorum) autumn forage yields have also been substantially in- creased by controlling soil nematodes (6). Field application of nematicides and fungicides is not practical on cool season forages at this time. Several thousand tall fescue and phalaris seed- lings have been screened for resistance to nematodes using techniques developed at Auburn (4, 5). Both resistant and susceptible plants have been selected for intercrossing to develop a resistant and a susceptible gene pool. Other screenings of cool season grasses have shown sufficient variability present to make progress towards nematode resistance. Nematode-resistant grass cultivars will take several years to develop. In the meantime, seed treatment with nematicide may serve as an economical deterrent to the nemode problem, particularly on annual grass species. Green- house studies at Auburn have shown that rye, wheat, oat, and ryegrass seed treated with very small amounts of systemic nematicide will reduce nematode numbers in the rhizosphere (8) . Oxamyl (Vydate) and carbofuran (Furadan) were relatively non-toxic to the seed while phenamiphos (Nemacure) was quite phyto- toxic. Relative tolerances of the grass species to nematicide seed treatment were rye>wheat>ryegrass>oats . 8 SUMMARY Nematodes are a major factor in reducing forage yields and stands of sericea lespedeza, vetch, tall fescue, orchardgrass , phalaris, ryegrass, rye, wheat, and oats in the southeastern USA. Legumes are attacked by root-knot nematodes while on grasses the major parasitic nematodes are stunt, stubby root, lance, and possibly dagger. Breeding for host plant resistance to nematodes will be necessary to im- prove forage yields and extend the geographical range of forage species. Ex- cellent progress has been made in achieving this objective on sericea and vetch. Seed treatment with nematicides on cool season annual grasses shows consider- able promise in reducing nematode populations to permit better root development and more autumn and early winter forage production. 9 LITERATURE CITED 1. Adamson, W. C., E. D. Donnelly, N, A. Minton, and J. D. Miller. 1974. Inheritance of resistance to Meloidogyne hapla in Lespedeza cuneata . J. Heredity 65:365-368. 2. Boyd, F. T., V. N. Schroder, and V. G. Perry. 1972. Interaction of nema- todes and soil temperature on growth of three tropical grasses. Agron. J. 64:497-500. 3. Donnelly, E. D. and N. A. Minton. 1968. Nematode-resistant sericea now possible. Auburn Univ. Agr . Exp. Sta. Highlights of Agric. Res. Vol. 15, No. 2. 4. Haaland, R. L. , C. S. Hoveland, and R. Rodriguez-Kabana . 1975. Nematode susceptibility of cool season grasses in the Southeast. Proc . 23rd Grass Breeders Work Planning Conf . St. Paul, Minn. 5. Haaland, R. L., G. R. Smith, C. S. Hoveland, and R. Rodriguez-Kabana. 1976. Development of nematode-resistant forages. Auburn Univ. (Ala.) Agric. Exp. Sta. Highlights of Agric. Res. Vol. 3, No. 3. 6. Hoveland, C. S., R. L. Haaland, and R. Rodriguez-Kabana. 1977. Soil nema- todes and forage production of some cool-season grasses. Proc. XIII Internat. Grassl. Congr . Leipzig, German Democratic Republic (In Press). 7. Hoveland, C. S., R. Rodriguez-Kabana, and C. D. Berry. 1975. Phalaris and tall fescue forage production as affected by nematodes in the field. Agron. J. 67:714-717. 8. Hoveland, C. S., R. Rodriguez-Kabana, and R. L. Haaland. 1977. Phyto- toxicity and efficacy of nematicide seed treatment on wheat, rye, oats, and ryegrass. Agron. J. 69: (In Press). 9. Hoveland, C. S., R. Rodriguez-Kabana, J. G. Starling, and J. S. Bannon. 1976. Cool season annual pasture mixtures as affected by autumn irriga- tion and nematicide in the Wiregrass area. Auburn Univ. (Ala.) Agr. Exp. Stn. Cir. 228. 10. Johnson, A. W. and G. W. Burton. 1973. Comparison of millet and sorghum- sudangrass hybrids grown in untreated soil and soil treated with two nema- ticides. J. Nematology 5:54-59. 11. McGlohon, N. E., J. N. Sasser, and R. T. Sherwood. 1961. Investigations of plant parasite nematodes associated with forage crops in North Carolina. N.C. Agric. Exp. Stn. Tech. Bull. 148. 12. Minton, N. A. 1965. Reaction of white clover and five other crops to Paratylenchus sceribneri. Plant Dis. Rep. 49:856-859. 13. Minton, N. A. and E. D. Donnelly. 1967. Additional Vicia species re- sistant to root-knot nematodes. Plant Dis. Reptr. 51:614-616. 14. Minton, N. A. and E. D. Donnelly. 1971. Reaction of field-grown sericea lespedeza to selected Meloidogyne spp . J. Nematology 3:369-373. 15. Minton, N. A. and E. D. Donnelly. 1973. Nematode-resistant sericea being developed. Georgia Agric. Res. Winters issue. 16. Minton, N. A., E. D. Donnelly, and R. L. Shepherd. 1965. Vetches and nematodes. Auburn Univ. Agric. Exp. Sta. Highlights of Agric. Res. Vol. 12, No. 3. 17. Minton, N. A., E. D. Donnelly, and R. L. Shepherd. 1966. Reaction of Vicia species and hybrids from V. sativa x V. angustif olia to five root knot nematode species. Phytopath 56:102-107. 18. Minton, N. A., E. D. Donnelly, and R. L. Shepherd. 1966. Reaction of varieties and breeding lines of sericea lespedeza to five root knot nema- tode species. Phytopath 56:180-182. 10 Forage-Fed Beef in Alabama By R. R. Harris Cool season annuals such as oats, wheat, and rye interplanted with rye- grass and clovers have provided an excellent method of growing beef calves in Alabama. Under ideal weather conditions and cattle suited to this pro- gram slaughter beef can be produced directly from grazing and without benefit of a drylot feeding period. This grazing program is adapted throughout Alabama and has been conducted effectively at 5 research stations, each with a different soil type. Results from three tests will illustrate typical animal performance. In a 10-year test conducted in northern Alabama, the grazing season began October 21 and ended May 15th. During this 207-day period cattle actually grazed 147 days and were off grazing because of inclement weather or lack of forage for 60 days. The calves had initial weights of 441 pounds and gained an average of 282 lb/steer for the season (ADG - 1.37 lb.). The gain per acre was 536 lb. when pastures were stocked at an average rate of 1.9 calves per acre. However, the gain per acre and per steer included gain made from supplemental feed pro- vided while off grazing. The ADG on grazing was 1.49 lb. and the gain from grazing only was 418 lb. per acre. In a 4-year test, rye, oats and wheat were planted with ryegrass and clover. A comparison was made of animal response from grazing each of these combinations. Rate of gain was similar (1.64 to 1.75 lb. ADG) but gain per acre favored wheat slightly (570 vs 498, 499 lb). Stocking rates were very similar among these three small grains (1.94 strs/acre). Oats did winter-kill during two years of the study and cattle were removed from oat grazing longer during mid-Winter (76 days for oats; 66 for rye; and 59 for wheat). In a 4-year test conducted in the Piedmont (central) area of Alabama, steer calved gained 2.0 lb. daily (394 lb/AC) from rye-ryegrass-clover grazing. Calves were larger than indicated for north Alabama tests (577 lb. vs 441, initial wts) . In this central Alabama test, grazing began on Dec. 7th and ended June 5th (193 days). Calves were never removed from grazing during that period nor were they fed anything. Stocking was much lighter (1/AC) even though cattle were heavier individually. Cattle from this central Alabama test were slaughtered directly from grazing without benefit of a finishing period. About 907, of their carcasses graded US Good and 107, were US Choice. Feeding of about 17, of bodyweight as shelled corn on grazing increased gain per acre only very slightly (47.) but did increase stocking rate to 1.5 steers/acre (507,) . In a south central Alabama test, early-maturing steers grazed oats-ryegrass- clover during a 10-year study. The initial weights were 544 lbs. and they gained an average of 294 lb per steer from grazing (ADG = 1.58). In this area, 11 grazing began November 1; ended May 5th; cattle were fed for an average of 27 days while on grazing during this 186-day season. Under optimum conditions for 5 years of the total (10), cattle were slaughtered directly from pasture with essentially 50% of the carcasses grading US Good and the remainder US Choice. As noted above, the cattle were early-maturing type and were not removed from grazing during the Winter period. SUMMARY Good-Choice slaughter cattle can be produced directly from cool season annual pasture without feedlot finishing provided conditions are optimum. Stocker calves have typically gained above 1.6 lb. daily while on such grazing; producing about 400 lb. of gain per acre. If conditions are not optimum for direct slaughter, then cattle from these small grain - clover pastures are ideally suited for feedlot finishing. 12 RECYCLING ANIMAL WASTE ON FORAGES By T. A. McCaskey Land application of manure has been practiced for centuries, partly be- cause there was no other place to put manure and partly because of the long recognized agronomic benefits resulting from manure. Manure has been shown to improve soil tilth, increase water-holding capacity, lessen wind and water erosion, improve aeration, and promote the growth of beneficial soil organisms. With the advent of increasing animal herds came the need to confine animals for more efficient management. For a herd of 100 dairy cows, each producing about 80 pounds of waste daily, the chore of managing the four tons of waste produced daily becomes a mounting problem. The fertilizer content of the waste amounts to about 16.5 pounds for total nitrogen, 5.2 pounds of P2O5, anc* 8.7 pounds of K2O for the 100-cow herd per day (Table 1) . Assuming that the waste is 20% solids the percentage of total nitrogen, P2O5, and ^2^ expressed on a dry weight basis would be 1.03%, .32%, and .54%, respectively. It is estimated that about two billion tons of animal waste are produced annually, enough to cover one square mile to a depth of 10 feet daily (5). During the turn of . the century nearly all of the animal waste was applied to land to make use of its nutrients for plant growth. However, as herds increas- ed in size waste was managed primarily to dispose of it rather than for soil amelioration and plant growth. Due to increased energy costs and the higher cost of mineral fertilizers the trend has been somewhat back to land applica- tion of waste. Studies at Auburn University with animal waste management are varied and include work with treatment and disposal systems, effects on soil, crop yield and crop quality, pollution control, animal feeding, and health aspects associa- ted with feeding waste to animals. Feeding studies began at Auburn about 1959, and studies with land applications began in the late 60' s. Safety studies with waste feeding were begun in 1975 and presently are increasing in importance worldwide . Land undoubtedly will remain the most logical place for ultimate disposal of manure. For this reason we must be concerned with rates of waste applica- tion that are consistent with good crop yields, yet do not interfere with crop quality nor pollute the soil or water. Some of the advantages of land dispo- sal of manure compared to lagoons and other systems of managing waste are shown in Table 2. Studies conducted at Auburn to determine the effect of various rates of dairy manure applied topically to Coastal bermudagrass showed that liquid waste applied at 20 tons/acre/year (T/A/yr.), expressed on a dry weight basis, by the irrigation or by the tank-wagon method did not appreciably affect the 13 TABLE 1. — Nutrient content of animal wastesa Total N P205 k2o Swine 4.3 - Pounds/100 animals/day 3.7 1.6 Poultry 2.9 2.9 1.0 Beef 16.0 16.0 4.7 Dairy 16.5 5.2 8.7 a/ From: Townshend, A. R. et al. 1969. Animal Waste Management, Cornell University, January 13-15, p. 131. MILLET- DOTHAN Manure application rate Dry matter (T/A) T/A I IQ HI 40 II. Or 1970 1971 1972 FIGURE 1. — Effect of manure application rate on Dothan soil. Yields with the same letter are not significantly different at the 5% level within years as determined by the Duncan Multiple Range Test. From: Lund et al . 1975. J. Env. Qual. 4:358. 14 quality of runoff water from the land (4). Pollution of ground and surface waters from land application of animal wastes is still a potential problem; however, the problem is much less severe than was originally thought. Millet and Rye Grown on Soil Incorporated Manure The effect of rate of land application of dairy manure on forage yield has been studied at Auburn by Agricultural Research Service scientists in coopera- tion with the Department of Agronomy (1,2,3). A three-year study was conducted to determine the effects of various rates of manure application on forage yield and quality of rye and millet double- cropped on two types of soils (2). Fresh dairy manure was incorporated into plots at the rate of 10, 20, 40, 80, 120 T/A dry weight basis before planting each year. The check plot (no manure) received 100 pounds/A each of N, P and K, and except for one of the three years of study, an additional 82 pounds/A each of N, and K was surface applied after each cutting. Two soil types were used in the study, one a Dothan loamy sand and the other a Lucedale fine sandy loam. The average analysis of manure N, P, and K on the soils following appli- cation is shown in Table 3. Millet was planted on all plots in the spring following fertilization. The millet was cut when it reached 50 to 64 inches height. Rye was planted in the fall and cut early the following spring. Millet yielded more forage on Dothan soil at high manure application rates than at lower rates, except in 1970 when emergence and early growth were re- duced at the high rates, probably due to ammonia toxicity (Fig. 1). One week after manure application surface soil pH increased to 8.7. The high applica- tion rates in 1971 and 1972 did not cause emergence failure and the pH of the soil did not rise substantially. Residue from the previous year’s application caused a buffering action that prevented a large increase in pH. The 40 T/A manure rate produced the highest yield of millet in 1970. During the next two years the highest millet yields occurred with the three highest manure appli- cation rates. Yields of millet on the Lucedale soil followed a pattern simi- lar to that on the Dothan soil (data not shown) . Yields of rye on Dothan soil in 1970 were not increased by manure applica- tion rates higher than 40 T/A. During the next two years yields were not in- creased significantly by manure rates higher than 20 T/A. On Lucedale soil (data not shown) the two highest rates of manure yielded the most rye forage for all three years. Nitrate content was higher for millet and rye grown on Dothan soil than on Lucedale soil (Fig. 2). Both millet and rye had nitrate N contents above .4% when 80 and 120 T/A of manure were applied. At the 40 T/A rate millet produced on the Dothan soil had nitrate N at about the .4% level considered toxic to ruminant animals. All forages were considered tetany prone with K/ (Ca+Mg) ratios above 2.2 except millet produced with the lowest manure application rate (10 T/A) and the check plot (Fig. 3). 15 TABLE 2. — Advantages of manure disposal on land 1. Economical. 2. Efficient aerobic decomposition of manure by microbes in soil. 3. If manure is plowed down, higher rates can be applied and fly, odor, and runoff pollution will be practically eliminated. 4. Improved crop yield from nutrients and organic matter. TABLE 3. — Average analysis of dairy cattle manure* N P K --------- Percent ---------- Dothan loamy sand 1. 98 (. 43-3. 12)a .67(.37— .83) 1 . 14 ( . 45-1 . 74) Lucedale sandy loam 1 . 91 ( . 77-2 . 64 ) .49(.37-.84) 1 . 25 ( . 54-1 . 56) aj Values in parentheses are ranges. From: Lund et al. , J. Environ. Qual. 4:195. TABLE 4. — Effect on manure fertilization on ratios of K/ (ca + mg) in Coastal bermudagrass forage* Dothan loamy sand Lucedale : sandy loam Treatment 1971 1972 1973 1971 1972 1973 Check 1.60 1.30 1.42 1.56 1.40 2.16 Dairy manure3 1.50 1.09 1.49 1.52 1.20 1.99 a / Average of all manure treatments. From: Lund et al. , 1975. J. Environ. Qual. 4:195. 16 FIGURE 2. — Effect of annual manure application rate on 3-year average nitrate level in forage. From: Lund et al . 1975. J. Env. Qual. 4:358. K/Co + Mg (equivalents) FIGURE 3. — Effect of annual manure application rate on 3-year average equivalent ratio of K/ (Ca + Mg). From: Lund et al. 1975. J. Env. Qual. 4:358. 17 Coastal Bermudagrass Grown on Soil Surface Applied Manure A three-year study was conducted to determine the rate of solid and liquid dairy manure that may be surface applied to established stands of Coastal ber- mudagrass on Dothan and Lucedale soils (3). Treatments consisted of a mineral fertilizer check and five manure treatment rates: solid manure at 20 and 40 T/A/yr. , and liquid manure at 20, 40, and 60 T/A/yr. Manure application rates were divided into six applications at approximately 2-month intervals, and all rates are expressed on the dry weight basis. Each week during the growing season at least 1 inch of irrigation was applied to the plots or 1 inch of rainfall occurred. The check plot received four applications of mineral ferti- lizer, totaling 470, 225, and 470 pounds/A/yr. of N, P, and K, respectively. These rates were high, but the rate of N was comparable to the amount of N estimated to be available per year in the lowest rate (20 T/A) of manure. Coastal forage was clipped on the plots when it reached 14 to 20 inches height. During the first year of the study the yield of Coastal bermudagrass on Dothan soil was less on plots receiving solid manure than on those receiving an equivalent amount of dry matter from liquid manure (Fig. 4). The nutrients in the liquid manure moved into the soil better and were available for plant growth. The 20 T/A rate of liquid manure produced less bermudagrass than the check plot indicating that not all of the nutrients were available for plant growth although the 20 T/A rate was similar in nitrogen fertilization compared to the check plot. The 40 T/A rate of liquid manure gave the same yield of bermudagrass as the check plot. In 1972 all treatments resulted in higher yields and the solid manure treatments produced as much forage as the liquid manure treatments at the same application rate (Fig. 4). Treatment effects on the Lucedale soil were similar to those for the Dothan soil (data not shown) . Nitrate N in the Coastal forage increased with the rate of manure applica- tion (Fig. 5). During the first year of the study the difference in nitrate N was ninefold (.015 to .141%) between the lowest (20 T/A) and the highest (60 T/A) manure treatments. Differences were also evident during the next two years of the study. The uptake of nitrate N was greater for Coastal grown on liquid manured plots than solid manured plots receiving an equivalent rate of application on the dry weight basis. None of the manure rates nor the check plot resulted in forage nitrate N levels greater than the .4% level considered toxic to ruminants. Grass tetany which may be associated with manured forages was not evident at any of the manure rates studied. The ratio of K/ (Ca+Mg) in the forages were below the tetanic level of 2.2 except the forage on the Luce- dale soil check plot during the third year of study (Table 4) . CONCLUSIONS Millet and Rye Grown on Soil Incorporated Manure Rates of 10 and 20 tons/acre of dairy cattle manure incorporated into soil produced millet and rye forage of good quality. When rates of application ex- ceeded 40 T/A forage was high in nitrate and had K/ (Ca+Mg) ratios that could be detrimental to animal health. When high rates of manure were used, the Dothan soil produced forage higher in nitrate than did the Lucedale soil. The • forage produced with high rates of manure on Lucedale soil had higher 18 COASTAL - DOTHAN Forage yield T/A II. 0 r Manure application rate Mineral fertilized 1971 1972 1973 FIGURE 4. — Effect of dairy cattle manure on yield of Coastal bermudagrass on Dothan soil. Bars with the same letter within the same year are not statis- tically different at the 5% level. From: Lund et al. 1975. J. Env. Qual. 4:195. Nitrate -N in forage (%) .30 .25 .20 .15 .10 .05 0 COASTAL- DOTHAN Manure application rate | | Mineral fertilized 1971 1972 1973 FIGURE 5. — Nitrate content of Coastal bermudagrass grown on manure-treated plots on Dothan soil. Bars with the same letter within the same year are not sta- tistically different at the 5% level. From: Lund et al . 1975. J. Env. Qual. 4:195. 19 K/(Ca+Mg) ratios than did that of Dothan soil with equal rates of manure appli- cation. Coastal Bermudagrass Grown on Soil Surface Applied Manure Split applications of dairy cattle manure totaling 20 and 40 T/A/yr. did not provide sufficient nitrogen for maximum production of Coastal bermudagrass forage the first year. Liquid manure was more effective than solid manure at an equivalent rate for forage production the first year. Accumulations from continuing applications at the 20 T/A/yr. rate produced excellent yields of high quality forage the second year on the loamy sand and the third year on the sandy loam. Rates of 20 T/A/yr, could be used for 3 years without im- pairing forage quality. Three years' application of manure at rates of 40 and 60 T/A/yr. had become detrimental to stand and weeds began to encroach upon the Coastal bermudagrass. There was also an indication that applications of 60 T/A/yr. over a period of years could produce Coastal bermudagrass forage with levels of nitrate that exceed tolerance levels for ruminant animals. These studies conducted by Auburn researchers indicate that 20/T/A/yr. of dairy cow waste (dfy basis) can be used in fertilization programs for millet, rye, and Coastal bermudagrass without impairing crop yield or quality. Higher manure application rates than 20 T/A/yr. can be used on Coastal bermudagrass without causing a tetanic condition or hazardous levels of nitrate in the forage. Millet accumulates nitrate and although 20 T/A/yr. of manure can be used the manure application rate should be reduced to 10 T/A/yr. after the second or third year of production. LITERATURE CITED 1. Doss, B. D. , Z. F. Lund, F. L. Long, and Luke Mugwira. 1976. Dairy cattle waste management: Its effect on forage production and runoff water quality. Auburn University Agri. Exp. Sta. Bull. No. 485, 39 pages. 2. Lund, Z. F. , B. D. Doss, and F. E. Lowry. 1975. Dairy cattle manure- Its effect on rye and millet forage yield and quality. J. Environ. Qual . 4:195. 3. Lund, Z. F. , B. D. Doss, and F. E. Lowry. 1975. Dairy cattle manure- Its effect on yield and quality of Coastal bermudagrass. J. Environ. Qual. 4:358. 4. McCaskey , T. A. 1973. Water pollution by dairy farm wastes as related to method of waste disposal. Auburn University Water Resources Research Institute, Bulletin No. 18, 87 pages. 5. Mehren, G. L. 1966. Aesthetics, economics - Animal waste. Proc. Nat. Symp. on Animal Waste Mgt., May 5-7, ASAE Publ. No. SP-0366 p. 4. 6. Townshend, A. R. , K. A. Reichert, and J. H. Nodwell. 1969. Status report on water pollution control facilities for farm animal wastes in the Providence of Ontario. Cornell University Conf. on Agri. Waste Mgt. January 13-15, p. 131. 20 GRASS ROOTS AS A TOOL FOR PENETRATING SOIL HARDPANS AND INCREASING CROP YIELDS By Charles B. Elkins, Ronald L. Haaland, and Carl S. Hoveland Most of the agricultural soils of the Southeast are coarse-textured. These sandy soils have low water-holding capacities and are easily compacted. Often the roots of common crops such as cotton, corn, and soybeans, are restricted to the plow layer by traffic pans. As a result of shallow rooting in these low-water-storage soils, plants are often subjected to water stress in 3 to 6 days after the soil is thoroughly wet by rainfall. For example, a typical Southeastern soil will store 1 inch of available water per foot of soil. If rooting is 6 inches deep and the crop is using water at a rate of 0.17 inch per day, then, following rainfall that wets the 6- inch rooting zone, the crop would have a 3-day supply of water (Table 1). After 3 days the crop would be under water stress until the next rainfall or irriga- tion. The table shows how length of time that the plants will be free from water stress increases as rooting depth increases. Actually, the benefits from deep rooting may often be greater than shown in the table because the water-holding capacity of many soils increases with depth. Ward et al. (5) have used long-term weather records, soil-water data, and water-use data to predict drought occurrence. From their work (Table 2), we determined that for the average Coastal Plain soil in east-central Alabama a crop with a rooting depth of 12 inches will, in 5 out of 10 years, experience 60 drought days during May through August. If rooting were 5 ft deep, the crop would experience only 11 drought days. Subsoiling usually comes to mind when one thinks of ways to break through traffic pans to promote deep rooting. However, crop response to subsoiling has often been variable (3), and any form of deep tillage increases energy require- ments. A highly desirable alternative to subsoiling would be plant roots with the ability to penetrate dense soil. Ideally, we would like to have this char- acteristic in each plant that we grow. This seems unlikely in the near future, but a useful second choice might be cropping sequences in which one plant in the sequence has roots that can penetrate dense soil. The penetrating roots would hopefully modify the soil hardpan and make possible deep rooting by following crops. 'Pensacola' Bahiagrass ( Paspalum notation Fliigge) One plant that shows much promise for such use is Pensacola bahiagrass. Observations in the Auburn rhizotron in glass-front boxes and in the field have shown that bahiagrass roots will penetrate artificial and naturally- occurring traffic pans that stop most crop roots. Doss et al . (1) found more bahia roots than common and Coastal bermudagrass ( Cynodon daotylon (L.) Pers.), sericea lespedeza ( L . cuneata (Dumont) Don) , and dallisgrass {Paspalum dilitatum Poir.) roots in the 6- to 36-inch depths of a Greenville fine sandy loam soil. Peterson, et al. (4) found morphological features of bahia roots that may explain their ability to penetrate dense soil. A predominant feature is a 21 SEED COTTON - hg/ha TABLE 1. — Days without plant water stress following rainfall for different rooting depths. (Available water = 1 inch/foot of soil; Evapotranspiration = 0.17 inch/day*) Rooting depth Days without water stress following rainfall inches 6 3.0 9 4.5 12 6.0 24 12.0 36 18.0 48 24.0 60 30.0 •k Average ET for south Alabama, May through August (from Ward et al. 1959. Drought in Alabama) FIGURE l.--The effect of Pensacola bahiagrass sod and deep tillage on cotton yield, Tallassee, Alabama. 22 SOD TURNED fibrous sheath beneath the epidermis that gives the root rigidity. In an experiment on a Cahaba loamy sand soil at Tallassee, Alabama (2), average cotton yields over 4 years were increased from about 1 bale per acre where cotton was grown continuously to about 2 bales per acre when cotton was grown after bahiagrass (Fig. 1) . Figure 2 shows that on continuous cotton plots, roots were restricted to the 9-inch (23 cm) plow layer, but grew to more than 24 inches (60 cm) when cotton followed bahiagrass. Numerous cotton roots were 6 ft deep on the bahiagrass plots. Soil water measurements showed that more subsoil water was removed by cotton following bahiagrass than by continuous cotton. Chiseling the soil 14 inches deep increased deep rooting and yield, but not as much as growing cotton after bahiagrass (deep tillage treatment - Figs. 1 and 2). The only measurable chemical or physical change in the soil that could explain the deep rooting and better plant performance of cotton following bahia- grass was the change in porosity of the traffic pan (Fig. 3) . Bahiagrass roots caused only a slight increase in small pores but an eightfold increase in pores greater than 1.0 mm in diameter. The primary roots of mature Pensacola bahia- grass are 1 to 2 mm in diameter. Bahia roots have a strong positive geotropism and, thus, form relatively straight vertical pores through the soil profile-- sometimes more than 6 ft deep. These pores through a traffic pan continuing into subsoil should be very effective in increasing saturated water movement and, thus, improve drainage, aeration, and water percolation in the compacted soil zone. They also provide channels through which roots of other plants can grow. Tall Fescue ( Festuca arundinacea Schreb.) Bahiagrass is best adapted to the mild climate of the southern Coastal area but plants with the ability to penetrate dense soil are needed for colder climates. Because of its widespread adaptability and use, tall fescue is an obvious plant to look to for this characteristic. Since preliminary evaluation indicated that tall fescue was heterozygous for root diameter, we screened 216 genotypes from four tall fescue lines for root size distribution. Two genotypes. Auburn 81 with a preponderance of small roots, and Auburn 7 with larger roots (Fig. 4) , were grown over compacted soil for 4 months. Roots of genotype 81 did not penetrate the compacted soil, but several of the 3.4- to 3.6-mm diameter roots of genotype 7 penetrated the compacted soil. The roots that penetrated increased in diameter by about 75% when they came in contact with the compacted soil and maintained this larger diameter until leaving the com- pacted soil, whereupon they returned to their original diameter. Tall fescue roots do not have a fibrous sheath as do bahiagrass roots. Bahiagrass roots do not increase in diameter when growing in dense soil, so different mechanisms for penetrating dense soil seem to operate in the two species. Conclusions and Plans for Additional Research We can conclude that at least on some soils, plants such as bahiagrass can be used to modify the porosity of traffic pans and improve performance of following crops. The bahiagrass cropping system is being tested on additional soil types with corn, peanuts, and soybeans. Tall fescue genotype 7 is being vegetatively increased for field testing on a traffic pan soil. Our objectives for ongoing and future research are to more fully understand the different mechanisms that roots use to penetrate dense soil, and to identify root 23 TABLE 2. — Probability of minimum number of drought days in east-central Alabama for soils with various water storage capacities. Month Prob . Area E Base amounts 1" 2" 3" 5" Minimum drought days May 1/10 25 21 19 7 2/10 23 18 14 4 3/10 21 16 11 1 5/10 17 12 6 0 June 1/10 25 25 24 21 2/10 23 22 20 16 3/10 20 19 18 12 5/10 17 14 13 6 July 1/10 22 20 20 18 2/10 18 17 16 14 3/10 16 13 13 11 5/10 12 9 7 5 Aug . 1/10 22 18 17 16 2/10 19 14 12 10 3/10 17 12 8 6 5/10 14 8 3 0 (From Ward, Henry S. et al. 1959. Agricultural drought in Alabama. Ala. Poly. Inst. Ag. Exp. Sta. Bull. 316) FIGURE 2. — The effect of Pensacola bahiagrass sod and deep tillage on cotton root penetration of a traffic pan in a Cahaba loamy sand soil, Tallassee, Alabama. (Dotted line shows depth to traffic pan.) 24 FIGURE CONTINUOUS COTTON COTTON AFTER BAHIA PORE SIZE! < 0.6mm-- • ’ 0.6-IOmm oj > 1.0mm 3. — Distribution of macropores in the traffic pan of a Cahaba loamy sand soil cropped to continuous cotton and cotton after bahiagrass. NUMBER of ROOTS GENOTYPE 25 characteristics associated with these mechanisms. Hopefully, these character- istics can be incorporated into useful cultivars . REFERENCES 1. Doss, Basil D. , D. A. Ashley, and 0. L. Bennett. 1960. Effect of soil moisture regime on root distribution of warm season forage species. Agron . J. 52:569-572. 2. Elkins, C. B., F. Lowry, and J. Langford. 1973. Alleviation of mechanical impedance to cotton rooting in dense subsoil by use of a sod. Agron. Abstr. Am. Soc. Agron., Madison, Wis. p. 122. 3. Parker, M. B. , N. A. Minton, O. L. Brooks, and C. E. Perry. 1976. Soybean response to subsoiling and a nematicide. Res. Bull. 181. Ga. Agr. Exp. Sta. 4. Peterson, Curt M. , Charles B. Elkins, and Pamela A. Roberts. 1976. Root development of bahiagrass ( Paspalum notation var. saurae ) : Light microscope and SEM studies. (Abstr.) Botan Soc. Amer. AIBS Meeting, New Orleans, May 1976. 5. Ward,1' Henry S. , C. H. M. van Bavel, J. T. Cope, Jr., L. M. Ware, Herman Bouwer. 1959. Agricultural drought in Alabama. Ala. Poly. Inst. Ag. Exp. Sta. Bull. 316. 26 ANTI-QUALITY RESEARCH ON FORAGES By R.L. Haaland, E.D. Donnelly, C.B. Elkins and C.S. Hoveland Sericea Sericea lespedeza (Lespedeza cuneata (Dumont) G. Don) , is a perennial warm-season legume well adapted to the southeastern United States. However, it has been found to have low palatability and nutritive value. In 1950, a breeding program was initiated at Auburn to improve the quality of the species . Both stem size and tannin content were shown to contribute to the poor quality of sericea (2, 3). By evaluating large populations for stem size and combining the fine stemmed material, an improved fine stemmed variety 'Serala’ was developed (4). Although Serala is a high tannin variety, beef cattle produced 88% as much gains on it as on Bahiagrass that received 168 kg of Nitrogen per hectare (9). Low-tannin sericea plants were found to have higher dry matter and crude protein digestibility than normal high-tannin plants (5, 6). Low-tannin was introduced into Auburn germplasm from a Beltsville selection, 23-864. Cattle grazed on a low-tannin sericea line performed better than on a high-tannin line (9). Performance on the low-tannin line equalled that on bahiagrass that had received 168 kilograms of nitrogen per hectare annually. Although low-tannin sericea shows much improved forage quality, it is not without problems. Tannins have fungicidal properties. Early low-tannin lines were found to be susceptible to Rhizoctonia sp. during hot humid weath- er. However, additional breeding efforts have produced disease resistant low-tannin lines (7). If resistance of this new material is adequate, it will make an expanded contribution to forage production in the Southeast. Phalaris Phalaris (Phalaris aquatica L.), a cool-season perennial forage grass, has the potential for excellent winter forage production in the Southeast. Phalaris has been grown in Australia for many years as a winter forage and animal metabolic disorders (staggers and/or death) have periodically devel- oped. These problems have generally been attributed to alkaloids found in phalaris. Phalaris genotypes investigated at Auburn have been relatively low in alkaloids, usually less than 0.3 percent of dry weight (1). A grazing trial on phalaris at the Black Belt Substation in Alabama resulted in steer gains of about 1.5 pounds per day and no metabolic disorders were evident . Tall Fescue Several million acres of tall fescue are grown for forage in the South- east. At times, ruminants grazing tall fescue will show symptoms of grass tetany. Grass tetany is caused by low blood serum Mg. Forages with low Mg content contribute to grass tetany. The tetany problem usually occurs during cool wet periods. Research at Auburn (8) has shown that low soil 02 will 27 depress Mg uptake in tall fescue. Forage grown on water logged soils common- ly found in late winter or early spring may be more conducive to grass tetany because of the low soil O2 • Initial screening of tall fescue germplasm has shown that there is variation for the ability to accumulate Mg at low O2 levels ( 8 ) . If this trait proves to be heritable new grass tetany resis- tant tall fescue varieties may be developed. Literature Cited » 1. Ball, D. 1976. Evaluation of toxicity potential of alkaloids in forage of Phalaris aquatica L. in Alabama. Ph.D. Dissertation, Auburn Uni- versity . 2. Donnelly, E. D. 1954. Some factors that affect palatability in sericea ! I lespedeza, L. cuneata. Agron. J. 46:96-97. ' 3. Donnelly, E. D. , and G. E. Hawkins. 1959. The effects of stem type on some feeding qualities of sericea lespedeza, Ij. cuneata as indicated in a digestion trial with rabbits. Agron. J. 51:293-294. I 4. Donnelly, E. D. 1965. Serala sericea. Crop Sci. 5:605. 5. Donnelly, E. D. , and W. B. Anthony. 1969. Relationship of tannin, dry matter digestibility and crude protein in sericea lespedeza. Crop Sci. 9:361-362. 6. Donnelly, E. D. , and W. B. Anthony. 1970. Effect of genotype and tannin on dry matter digestibility in sericea lespedeza. Crop Sci. 10:200-202. 1 7. Donnelly, E. D. 1976. Breeding for improved forage quality in sericea lespedeza. Proc. 33rd SPFCIC. Miss. State, Miss. 8. Elkins, C. B. , R. L. Haaland and C. S. Hoveland. 1977. Tetany potential of forage species as affected by soil oxygen. XIII International Grass- land Congress. Leipzig, German Democratic Republic. 9. King, C. C., W. B. Anthony, R. F. McCormick, Jr., and Fred T. Glaze. 1975. Cow-calf performance on low- and normal-tannin sericea (Lespedeza cuneata) . Abst . Sou. Assoc, of Agr. Scientists. p. 4. SYSTEMS FOR BACKGROUNDING CATTLE By H. W. Essig The Southeast continues to be a leader in beef cattle production. The bulk of this beef production has been largely centered around the cow-calf operation, in which the calf is weaned and sold at weaning time. With advanc- ing technology, expansion of farm size and lowered demand for young cattle, many producers are retaining ownership of their weaned calves and attempting to increase the weight to approximately J00 lb. This period of time from weaning to growing the animal to an appropriate size for placing in a finishing program is often referred to as "backgrounding." My talk will be centered primarily around systems for growing cattle from weaning to a weight sufficiently large enough to allow the animal to be placed on a feeding system. There are many confusing terms related to backgrounding of cattle. The terms "preconditioning," "conditioning," "backgrounding," and "stocker pro- grams" are quite often interrelated and are oftentimes used synonymously. I would like to offer some definitions for these terms. "Preconditioning" is often defined as preparing the calf to better withstand the stress of leaving its mother and learning to eat new kinds of feed. Generally, preconditioning is performed on the animal prior to weaning and is done by the cow-calf pro- ducer before the animal is sold. Preconditioning involves such management practices as identification, castration, dehorning, weaning, immunization, nu- tritional adjustments, external and internal parasite controls, as well as allowing the animal to become accustomed to handling. In essence, precondi- tioning is nothing more than good management practices. "Conditioning" may be defined as preparing the weaned animal to withstand stress associated with readying for the feedlot. The conditioning practices would be nothing more than applying the management practices that were not administered during a pre- conditioning phase. "Backgrounding" is defined as a practice used by some feedlot operators to get calves accustomed to their new environment before they are placed in the feedlot. This definition is the one that was originally applied to the practice of backgrounding. However, this definition has now changed to a great extent to cover the period of time between weaning and the time the animal is placed in the feedlot. This broad definition also would be synonymous with stocker programs in which young cattle are grown from wean- ing until entering the feedlot or breeding herds. These cattle are usually referred to as "stockers." In the Southeast, the stocker programs are gener- ally synonymous with backgrounding programs . The Southeast is ideal for stocker or backgrounding programs since the climate is conducive to good year-round forage production and utilization sys- tems. With the proper combination of warm and cool season legumes and grasses, the growing season can be stretched to nearly 365 days per year. This is par- ticularly true for areas near the Gulf Coast. However, as operations are located further north from the coastal area, the growing season decreases to less than the 365 days per year. The Southeast has an abundance of rainfall, and a large portion of this rainfall is spread throughout the year, allowing 29 for forage production from either warm season or cool season forages. Capital for livestock operations has "been somewhat of a problem in past years; however, there appears to he a greater availability of capital for livestock production in the Southeast in recent years. This is particularly true with the advent of the backgrounding programs, in which the cool season annuals supply a bulk of the forage for the backgrounding programs. Fertilizer has been available and in the past, has been a relatively economical source of nutrients for plants and has allowed for economical production of forages. The Southeast has soils that are adaptable to forage-livestock systems and has topography that allows for grazing during a large portion of the year. There have been marketing channels developed in the Southeast. These allow the producer to retain owner- ship of animals through the backgrounding phase and then market these animals or retain ownership of the animals and place them in feedlots. These alterna- tives provide the producer the opportunity to maintain ownership through a fin- ishing program or to dispose of the animal upon completion of a backgrounding program. One final point that makes the Southeast an ideal stocker-background- ing area is the native ability for managing the complex microenvironment-soil- plant-animal farming business. With all of these advantages, the Southeast is in the driver's seat as far as the stocker or backgrounding programs are con- cerned. There is no other area in the country that has the advantages for a backgrounding program that occur in the Southeast. Livestock-forage systems can be divided into different schemes (fig. l). In this breakdown, the forage systems are divided into grasses and legumes, with the grasses and legumes further divided into annuals and perennials. The annuals and perennials can further be divided into warm season or cool season annuals or perennials for which some examples have been given. Warm season annual grasses would include such things as corn, sorghum, or some of the sorghum-sudan hybrid crosses. Generally corn or sorghum would either be pro- duced for silage, harvested for grains, or both. The sorghum-sudan cross mate- rials could be either grazed or harvested as a stored forage. The cool season annuals would be such things as the cereal grains or rye- grass, or a combination of the various cereal grains and ryegrass. This is often referred to in the Southeast as "winter grazing," and there are programs which use wheat, oats, rye, ryegrass, triticale, singularly or in combination. These programs may also be combined with clovers. There is a host of perennial warm-season grasses, of which the bermudagrasses are probably the most prev- alent. Bahiagrass is also abundant in the extreme southern portion of the Southeast, and the bermudagrasses would occur throughout the southeastern United States. The cool season perennial grasses such as fescue occur in the upper Southeast and orchard grass occurs in the extreme northern portion of the Southeast. The systems division for legumes also contains annuals and perennials. A good example of a summer annual legume would be lespedeza. There is a variety of annual winter or cool season clovers such as as the arrowleafs , crimson, and subterranean clover. These annual clovers are used in combinations with the cool season annual grasses and afford very profitable systems of livestock production. The perennial legumes are used generally in combination with some of the perennial grasses. Perennial legumes that are used are the ladino clovers and some red clover. Alfalfa may be used, but generally alfalfa is used more for a hay crop than it is for a grazing crop in the Southeast. This outline for forage systems involving grasses and legumes for annual or perennial cool season or warm season production is by no means a complete list. All of these forages should be considered for use in forage systems in the Southeast. 30 FORAGES GRASSES ANNUALS PERENNIALS WARM SEASON COOL SEASON WARM SEASON COOL SEASON 5 LEGUMES ANNUALS PERENNIAL WARM COOL SEASON SEASON CORN SORGHUM WHEAT OATS RYEGRASS BERMU DA- GRASSES BAHIA FESCUE LESPEDEZA CLOVER ALFALFA ORCHARD- CLOVERS GRASS FIGURE 1. — Plant components of livestock-forage systems. ENERGY PRODUCTION JAN JUNE DEC FIGURE 2. — Generalized pasture availability curve. 31 In developing backgrounding systems, the objective is to use as many com- binations of cool season perennials, warm season perennials, and the winter annuals as possible, in order to produce as large a quantity of high-quality forage as possible. A generalized pasture availability curve has been con- structed (fig. 2). This diagram indicates the relative energy production for the winter annuals, the cool season perennials and the warm season perennials. By looking at this generalized production availability curve for different for- ages it is obvious that forage utilization systems need to be constructed that will allow for maximum energy usage during the period of time from early spring through July. A generalized scheme for an energy requirement of a growing animal shows the energy requirement is on a continuing or rising basis. This energy requirement generally is a function of body weight, so that as the ani- mal increases in weight, the energy requirement for maintenance is increased. When this maintenance energy requirement is combined with the energy require- ment for gain, the total energy requirement increases in a linear manner (fig. 3). If the energy requirement of the growing animal is imposed on the energy production for the different forage systems, it is apparent that as the animal increases in weight or size, the energy requirement increases and that there is the possibility that late in the season the energy requirement of the ani- mal may be greater than the energy production potential of the forage system. This indicates that in a forage-livestock production system, it is imperative to utilize the forage that is produced in the early portion of the season. The area in the forage production system in which there .is a need for development of forages to be used in a year-round forage system is during the period of time from late summer through late fall. There are many possible backgrounding systems that may be derived using different cool season annuals, perennials, grasses or legumes. Some possible i systems have been assembled that are workable in the Southeast. These systems may apply in some geographical areas and not in others. Not every system will work in every area of the Southeast. In all systems cattle used were weaned in October with the objective of achieving an arbitrary weight of approximately 1 TOO lb. This would be the backgrounding period that was previously defined as being the period of time between weaning and prior to being placed on a fin- ishing program. The first system is one in which the initial weight of the animals would be somewhere between U00-500 lb. These animals would start on the system in October at weaning and would end sometime in early April. In this system corn silage would be the basic forage. Corn silage could be fed at ' a rate of about 27-5 lb per day, along with ^ lb of ground shelled corn and 1.5 lb of protein supplement daily. Research has shown that this system will pro- duce 1.6 or more pounds of daily gain. Using this system the producer could utilize the corn silage over a l80-day period after which the animal should weigh at least TOO lb and would be ready to go into a finishing program. This type of program would be adaptable to the livestock producer who has the capa- bility to produce a high quality corn silage and has facilities necessary for a feeding system. The second system that might be used would utilize a weanling calf weigh- ing i+00 to 500 lb starting October and ending in May. This could also be a corn silage program in which the animals were fed approximately 30 lb of corn silage with a protein supplement of 1.5 lb daily with expected daily gains in the range of 1 to 1.25 lb. This system would require approximately 250 days to get the animals to weigh in excess of TOO lb. This program would perhaps be ! less expensive if the producer had the capability of producing a good quality 32 ENERGY JAN JUNE DEC FIGURE 3 . --Generalized energy requirement for a growing animal. ENERGY FIGURE 4. — Pasture availability curve and energy requirement for growth. 33 corn silage and did not have a need to move the animals at a quick rate in order to make room for other animals in a feeding operation. The third system could be one in which the initial weight might range be- tween 350 to 450 lb starting in October and ending sometime in July. This pro- gram would use a hay-corn-protein supplement regime from October through March. During this period the animals could be fed about 10 lb of a high-quality hay per day with 4 lb of ground shelled corn and 1.5 lb of protein supplement. The expected average daily gain would be about 1.35 lb per day from October to March. In April these animals could then be transferred to a perennial pasture consisting of bermudagrass-clover and be maintained on the pasture from April through July with an expected daily gain of at least 1.25 lb for the 120-day period. Again, by the end of July, the animal should weigh over 700 lb and be ready to be placed on a finishing program. The fourth system outlined is one in which the initial weight could be between 400 and 500 lb, again starting in October and allowing for the animals to weigh above 700 lb by late June to early July. The animals could be main- tained on a fescue-clover pasture at a rate of one animal per acre during the period from October to March. During the period from December to March, about 100 days, there would probably be a need for supplementing the calves with some hay and as much as 8 lb of grass hay and 1.5 lb of cottonseed meal might be required. It is anticipated that the calves would gain about .75 lb per day from October to March. Then from April through June, the animals could be maintained on the fescue-clover pasture at a rate of one animal per acre, with expected gains of 1.6 lb per head per day. These cattle would then be ready to be placed on a finishing program in late June or early July weighing in excess of 700 lb. The fifth system that I have outlined would be one in which the initial weight might be from 300 to 400 lb and start in October and end in late June to early July. This system would require an adjustment .period during October and November in which the animals could be placed on a fescue-clover pasture at the rate of one animal per acre with an anticipated average daily gain of about .3 pound. From December to February the animals could be changed to a wheat pasture at the rate of .75 acre per head. If a wheat-soybean rotation might be in the overall farm program, this would allow animal utilization of the wheat. During this period of time, there is the possibility that at least 30 days of feed may be required. This feed might be 8 lb of grass hay, 4 lb of corn and up to a pound of cottonseed meal. Gain during this period of time from Decem- ber through February could be expected to be about 1.1 lb daily. During March the calves could be returned to the fescue-clover pasture with additional hay, if necessary, plus about 3 lb of corn and stocked at a rate of one animal per acre with an anticipated daily gain of about 1.5 pounds. From April through June the animals could be retained on the fescue-clover pasture at the rate of one animal per acre and average daily gains could be as much as 1.6 pounds. The animals should weigh about 700 lb by the end of June and thus, could then be placed on a finishing system. System six utilizes animals weighing from 4-00 to 500 lb starting in Octo- ber and ending in May. This system would utilize an adjustment period of bermuda and clover or fescue and clover during the months of October and Novem- ber and stocked at a rate of one animal per acre. Average daily gain of about .3 or more lb per day would be expected. In late November to early December, the calves could be transferred to a cereal grain- ryegrass-clover pasture, stocked at a rate of about 600 lb of initial weight per acre. This would be one-and-one-half 400-lb animals per acre and maintained at this initial 34 stocking rate throughout the duration of the system. Depending upon the geo- graphical area, there may he as much as a 30- to 45-day supplemental feed requirement. About 8 to 10 lb of hay and 1.5 lb of protein supplement would be needed during the months of January and February. During the supplemental feed period the average daily gains would drop perhaps as low as .75 pound. In March, April and May the cereal grains, ryegrass, annual clover would again display vigorous growth and gains during this period could be as much as 1.9 to 2.0 lb daily. These animals should weigh about 700 lb by the end of May and be ready to be placed on a finishing system. The seventh system is one in which the initial weight might be as low as 300 lb starting in October and ending in late July or early August. In this system an adjustment period for the weaned animal would be to place the animal on a bermuda-clover or fescue-clover pasture at a rate of one animal per acre during the months of October and November. Expected daily gain for this period would be about . 3 pound. From December to May the animals would be placed on a cereal grain- ryegrass-annual clover-red clover mixture with antici- pated gain of 1.5 lb per day. During the months of January and February 30 to 45 days of supplemental feeding might be required. The supplemental feed might be hay or silage. About 10 lb of hay or hay equivalent and 1.5 lb of protein supplement could be fed with an anticipated average daily gain of .75 pound. In March, April and May the cereal grain-ryegrass-annual clover-red clover combination would be at its maximum productivity and average daily gains could be expected to .go as high as 2.0 pounds. From the middle of May to the end of July the annual forage residue could be grazed along with the red clover and an expected gain would be about 1.6 lb per head daily. The animals that were started on this program should weigh in excess of 700 lb and would be ready to be placed on a finishing system by July. I have listed several forage systems that might be used in a background- ing program. I would, however, like to list some of the grazing systems that might be employed in the different backgrounding systems that I have just covered. Continuous grazing is the system that is quite often used in most of the winter annual grazing experiments. There is some evidence to indicate that rotational or strip grazing will increase the productivity of beef per acre. There are data from several institutions that have indicated that if a rotational grazing system is followed, that the beef production per land area can be increased by as much as 25 pounds per animal. There is also a recom- mendation that certain of the cool season forages be allowed to be deferred, which is nothing more than to allow forage to grow in one area, then place animals on the forage after it has obtained an abundance of growth. I have listed a number of forage-livestock production systems that can be used. I would like to stress five "CANS" that should be considered in a forage production and utilization system. I think it is obvious that the producer CAN grow more forage. It i s apparent that the producer should grow all the forage that he CAN. He should CAN all the forage that is produced, as to whether this be by an animal or in some type of structure or apparatus for future feeding, it should be harvested. The livestock producer should utilize all of the forage that he CAN. It is of little value to produce a forage and then not utilize it. The producer should sell all the forage through livestock that he CAN. Generally the most profitable means for sell- ing forage is by taking the animal from weanling through a backgrounding sys- tem. 35 PRODUCING SLAUGHTER BEEF BY SUPPLEMENTING PASTURE By M. B. Wise Cattle finishing is a growing enterprise in the Southern United States. Increased demand for high quality beef and improvement of pastures have con- tributed materially to success in this area. Research at the North Carolina, Georgia, Louisiana, Alabama, Arkansas and Virginia Agricultural Experiment Stations has shown that one of the best methods of increasing returns from a cattle finishing program is the inclusion of high quality pasture as a major feed ingredient. Good quality pasture supplies most of the nutrients necessary for growth and finishing. Protein and vitamins are supplied in amounts that will meet the animals need. The primary nutrient which must be supplemented to grazing steers is energy. Also additional minerals may be necessary. The research reported herein revolves around the supplementation of energy to steers finished on pasture. The "grain on grass" system takes advantage of our natural resources and furnishes a good return to land, labor and management. This system might also be characterized as a "low risk" system of finishing cattle. It requires a minimum of labor and is applicable to almost any size of operation which is able to produce excellent pasture. This system also minimizes the waste man- agement problems encountered in dry-lot fattening. Studies concerned with the feeding of grain on pasture have been conducted over a number of years. Early experiments at N. C. State University (Wise et_ al . 1965) involved a determination of the most economical level of grain to feed steers grazing clover-grass pastures. This work indicated that a level of 0.8 to 1% of the animals' body weight gave greatest financial returns (Table 1). Since the pasture season is a period during which most farmers are quite busy with other farm work, it was considered desirable to find a method which would allow self-feeding of grain on pasture without worry of the cattle over- eating. Several studies showed that a mixture of 90% ground shelled corn and 10% animal fat was consumed by grazing steers at a level of about 0.8 to 1% of their body weight. Five experiments dealing with stilbestrol, showed that gains of grazing steers consuming the corn-fat mixture was increased from an average of 2.12 lbs. for control steers to 2.58 lbs. per day for steers im- planted with 24 mg. of sti 1 bestrol --an increase of 22%. The implantation of stilbestrol at the beginning of the fattening period also caused a decrease in concentrate necessary per pound of gain from 3.14 to 2.65. In other experi- ments, antibiotics were added to the corn-fat mixture and fed to one group of steers in each experiment. Other groups of steers received the corn-fat mix- ture without an antibiotic added. The addition of antibiotic (in this case Aureomycin) at a rate of 70 to 100 mg. daily resulted in an increase in daily gain of 0.1 lb. Although this was a small increase, the additional gain more than paid for the cost of the antibiotic. Research has also been conducted 36 which indicates that plant fats such as crude cottonseed oil may be used to limit the concentrate intake of grazing steers and that other grains such as milo may be used instead of corn. Green-chopping does not appear to be econom- ically advantageous for fattening steers under present conditions in this area. Results also indicate that grass pastures supply sufficient protein for fatten- ing steers fed an energy supplement of 90% corn with 10% fat, however, extra protein may be necessary under some conditions. A four year study (Wise et al . 1967) involving 304 steers (see Table 2) has also demonstrated that nitrated Coastal Bermudagrass may also be used in a "grain-on-pasture" program for fat- tening cattle. An extra source of protein is of questionable value in this system. Subsequent studies at the North Carolina Station have demonstrated that the grain-on-pasture system is adaptable to the finishing of heifers, that Melengestrol Acetate (MGA) is useful in preventing estrus in these finishing heifers and that wheat can be used successfully as the supplemental energy source in the grain-on-grass system (Barrick et^ aj_. 1976). Recent work at the Virginia Experiment Station (McCl augherty et al 1975) has been concerned with finishing steers and heifers in a system that maximizes the use of pastures consisting of blue grass orchard grass and white clover. This system takes advantage of the early spring "flush" of pasture and the fact that heifers normally finish earlier than steers. Steers and heifers in equal numbers were allowed 0.5 acres of pasture in mid-April and self-fed rolled corn with 10% added animal fat. In mid-July the heifers were marketed and the steers were allowed to graze the additional acreage vacated by the heifers giving them a total of one acre per head after that date. Results of studies during the three years are shown in Table 3. The Virginia data demonstrate that this finishing system is adaptable to a blue grass, orchard grass, white clover pasture and that good use can be made of pasture for the entire summer season by a regulated marketing system. Research at the Georgia station (Lowrey et al . 1972) has shown that grain feeding on pasture is applicable to the production of finished cattle during the winter season. Permanent pastures of cool season perennial species and temporary winter pastures consisting of small grains seeded in the fall were successfully used as the forage source. Highly acceptable gains and carcasses resulted when a grain mixture was offered ad 1 ibi turn. Research at the Louisiana Experiment Station has covered several areas of the use of pastures in finishing programs indicating a wide application of the grain-pasture system. A good example of this work (Carpenter, Klett, and Hembry, 1971) includes a 5-year study in which 450 pound steers were purchased in October and grazed for 299 days with various concentrate supplements. The pasture (a total of 1 acre per steer) consisted of equal acreages of fescue, Coastal bermudagrass and common bermudagrass . The Coastal and common bermuda- grass was overseeded in November with common ryegrass. All pastures were well fertilized and nitrated. A period of 196 days (Nov. to May) was considered the winter period and 103 days (May to September) was considered the summer period. Five supplements containing varying amounts of ground corn, cottonseed meal, urea and limestone were used and salt was added to limit intake. All 37 treatments produced acceptable slaughter cattle as indicated in the combined w i nter-summer data. The Louisiana research demonstrates that a wide variety of rations can be successfully fed on pasture, that salt can be used to limit in- take and that energy is the major nutrient that needs to be supplied in pasture fattening of cattle. One of the major deterrents to the use of pasture in the finishing process is the slight yellowish tinge of the fat of the resulting carcass since some packer resistance is encountered. It should be noted that this yellowish cast is a result of carotene deposition and hence furnishes vitamin A to the con- sumer of this meat. Once the packer and consumer are educated to this fact much of the resistance tends to disappear. SUMMARY I i Research data from Experiment Stations and successful application by prod- ucers in the Southern United States have demonstrated that the use of limited grain on good pasture is an excellent method of finishing cattle. This system ; using concentrate intake limiters is applicable to both summer and winter grow- ing forages, yields acceptable returns to land and capital, has a low labor requirement, and provides an answer to the waste management problems that are presently encountered in dry-lot systems. This system takes advantage of the tremendous capacity of the Southern United States to produce. high yielding forage and is applicable wherever high quality forage can be produced. LITERATURE CITED Barrick, E. R. , T. N. Blumer, M. B. Wise, B. K. Ashford, A. C. Canto and B. C. Allison. 1976. Finishing heifers on pasture with limited grain feeding. N. C. Agr. Exp. Sta . Bui. 452. Carpenter, J. C. , Jr., R. H. Klett and F. G. Hembry. 1971. Producing slaugh- ter steers with grain self-fed on pasture. La. Agr. Exp. Sta. Bui. 659. Lowrey, R. S., W. A. Griffey, H. C. McCampbell and G. V. Calvert. 1972. Feed requirements and management practices for the production of steers in the Piedmond. Ga . Agr. Exp. Sta. Mimeo. McClaugherty , F. S., J. P. Fontenot, R. F. Kelly, M. B. Wise and R. C. Carter. 1975. Systems of fattening cattle in Southwest Virginia. Livestock Res. Report, p. 18. Va. Res. Div. Report 163. Wise, M. B., E. R. Barrick, and T. N. Blumer. 1965. Finishing steers with grain on pasture. N. C. Agr. Exp. Sta. Bui. 425. Wise, M. B., H. D. Gross, R. S. Soi kes , E. H. Evans, Jr. and E. R. Barrick. 1967. Supplementation of Coastal bermudagrass for finishing steers. N. C. Agr. Exp. Sta. Bui. 430. 38 TABLE 1. Performance and concentrate intake and conversion of steers fed vari- ous energy supplements while grazing clover-grass pastures*. (North Carolina Experiment Station). Average Daily Daily Cone . Cone Gai n Intake Gain Lb. Lb. A. Concentrate level - 1 experiment - 50 steers Corn, % of body wt: 0 1 .22 0 0 0.5 1 .60 3.4 2.04 1.0 1.93 6.4 3.31 1.5 1 .93 8.0 4.15 1 .5 last 60 da 1 .45 2.6 1 .79 B. Intake limiters - 3 experiments - 130 steers Corn-hand fed 2.15 5.08 2.23 Corn + 10% sal t 2.27 6.33 2.79 Corn + 1 0% fat 2.54 7.72 3.04 Corn + 1 0% animal fat 2.56 8.90 3.48 Corn + 10% cottonseed oil 2.62 9.94 3.79 C. Diethyl sti 1 bestrol - 5 experiments - 182 steers No sti 1 bestrol 2.12 6.66 3.14 24 mg stilbestrol (implanted) 2.58 6.83 2.65 D. Antibiotic (Aureomycin) 3 experiments - 92 steers Corn + fat No antibiotic 2.27 5.85 2.58 Corn + fat 70-100 mg. antibiotic 2.37 6.33 2.67 E. Corn vs milo - 1 experiment - 36 steers Corn + 10% animal fat 1 .85 9.24 5.00 Milo + 10% animal Fat 1.77 9.34 5.28 F. Green chop vs pasture - 2 experiments - 80 steers Pasture + corn with 10% fat 2.50 9.4 3.70 Green chop + corn with 10% fat 2.32 12.0 5.17 39 TABLE 1. Performance and concentrate intake and conversion of steers fed vari ous energy supplements while grazing clover-grass Carolina Experiment Station). (Continued) pastures*. (North Average Dai ly Da i 1 y Cone . Cone . Gain Intake Gain Lb. Lb. G. Protein sources - 2 experiments - 80 steers Pasture + corn-fat 2.76 11.26 4.08 Pasture + corn-fat + SBM (10%) 2.98 13.63 4.57 Pasture + corn-fat + N on sod (120#A) 2.65 9.91 3.74 Pasture + corn-fat + clover in sod 2.90 10.41 3.59 *In all experiments 600-700 pound calves were allowed .8-1 acre of Ladino cl over-gra-ss pasture and were fed minerals free choice. Minerals consisted of one box containing a mixture of 2 parts steamed bone meal (or dicalcium phos- phate) plus 1 part T.M. salt and a second box containing plain salt. 40 TABLE 2. Performance of finishing steers fed various supplements while grazing nitrated Coastal bermudagrass . Averages of 4 year study (N. C. Ex- periment Station). Treatments9 P P+E P+Pr P+E+Pr Total steers/treatment 76 76 76 76 Av. no. days on experiment 163 163 163 163 Av. initial wt., lb. 682 671 677 671 Av. final wt. , lb. 869 1025 906 1043 Av. gain/steer, lb. 187 354 229 372 Av. daily gain, lb. 1 .15 2.16 1 .40 2.27 Av. Daily concentrate, lb. -- 10.86 1 .50 10.87 Concentrate/gain -- 5.03 -- 4.79 Av. carcass grade*3 8.3 10.1 8.5 10.1 treatments : P= Coastal bermudagrass pasture (CB) P+E = CB + 90% corn and 10% animal fat - self- fed P+Pr ^ CB + l.b lb/hd/day of soybean meal (SBM) P+E+Pr = CB + 80% corn, 10% animal fat and 10% SBM - self -fed tased on 8 - high standard. 9 = low good , 10 = average good. 11 = high good, etc. 41 TABLE 3. Management pasture (V No. animals Initial wt. , lbs. Wt. mid-July Av. daily gain Wt. mid-October Av. daily gain Grain-fat/day , lb. Grain-fat/lb. gain Carcass grade3 Rind thickness, in. alow good = 9, systems for finishing steers and heifers with grain on irginia Experiment Station). Average 1972, 1973 & 1974 Hei fers Steers 36 36 585 605 751 802 2.37 2.81 -- 1015 -- 2.44 9.6 10.0 4.1 4.1 9.9 10.4 .48 .65 middle good = 10, high good =11, etc. 42 FINISHING SLAUGHTER CATTLE WITH GRASS AND GRAIN By John C. Carpenter, Jr. A large amount of quality beef is consumed in Louisiana each year, but very little is produced. With the growing demand for beef and the economic pressures requiring greater efficiency, there is definitely a need for intensifying beef produced per cow and per acre . Livestock producers in Louisiana and the southeastern United States are realizing more each year their advantage in forage production over other sections of the country. Our geographical location makes possible the production of both winter and summer pastures. While our summer pastures of bermudagrass , dallisgrass and bahiagrass have a high carrying capacity, the winter pastures of ryegrass, wheat and rye with clovers are our real bonus in the production of beef. Because in many instances the economic return from the aver- age weaned calf is insufficient to cover cow cost during the year, many beef producers are holding calves after weaning, grazing them, and either selling them as yearling cattle or carrying them to slaughter weights and selling them. In this way, the producer is essentially selling two calves per cow investment. It is my belief that we should wean heavier calves and main- tain ownership all the way to the rail. We have produced our heaviest calves by using a creep grazing area, especially for the calves, within each pasture unit. In a thirty acre area, divided into two tens and two fives, the cows had access to the twenty- five acres and the calves to the five acre creep anytime they wanted. Cows only grazed the creep area when it got ahead of the calves. Twenty-five cows and calves, four heifers and two bulls were carried on this thirty acres of pasture. Each year for four years, 15 tons of excess hay were produced. For four years, an average of the first two 205-day periods showed calves in this herd averaged 103 pounds heavier than calves in the herd where calves didn't have access to a special creep grazing area. In 1975, ten calves weaned on August 1 from this herd, averaged 579 pounds. The heaviest 700, and the lightest 455. In 1976, calves were not as heavy as in 1975, but there were a good many 600 to 670 pound calves from the four herds in the study. 43 At the Northeast Louisiana Experiment Station, St. Joseph, Louisiana, in earlier trials, it was found that beef calves fed a concentrate supplement while grazing fescue pastures, had a higher daily gain and slaughter grade than calves grazed without supplemental feed on the same type pasture. At the end of these trials cattle were graded on foot only and because of their light final weight, were sold as feeders rather than slaughter animals, so no carcass data were available (1_) . Yearling steers fed a grain supplement either on coastal or common bermudagrass pastures had a higher daily gain and slaugh- ter grade than non-fed steers. When graded on the live animal basis at the end of the trials, the fed steers graded Good to High Standard and the non-fed steers graded Standard. In two of the three trials, the fed steers graded Good to Standard on the carcass basis. When slaughtered, 58 percent graded Good and 42 percent Standard. Steers grazed without grain were not fat enough to suit the packers, so they sold as feeders and were fed in dry- lot prior to slaughter (1_) . In earlier work at the West Louisiana Experiment Station, Angus steers were grazed on winter pasture for two years. Steers were approximately 18 to 30 months of age and weighed approximate- ly 912 to 1092 pounds, and were graded 50 to 87 percent Choice. On these steers marketed in May, the fat was extremely yellow. In 1970 we looked at steers slaughtered at two years of age in February. The fat was not yellow, and approximately 50 percent of these steers graded Choice (2) . In the 1960's at the Northeast Louisiana Experiment Station at St. Joseph, concentrates were fed to steer calves grazing pas- ture for 300 to 350 days. Approximately one ton of feed was re- quired per steer. Concentrates were fed to one group at a con- stant level of eight pounds per head daily and to the other group at one pound per head daily per 100 pounds of liveweight. Thus, the amount of concentrates fed to the latter group was increased with each 100 pound increase in body weight. The steers fed at the one percent level carried a higher degree of finish as ob- served after approximately 220 days in each trial. Forty-five percent of the steers in this group graded Choice when slaugh- tered, as compared with twenty percent in the group fed at the constant level during the trial. All carcasses exhibited superi- or marbling and rind fat that was fairly thin and white (3) . Using a ration containing 90 percent corn meal with ten per- cent salt, in three trials, beef steers averaged 1.77 pounds dai- ly for 299 days. The ration intake averaged 6.80 pounds per head daily in addition to the pasture. The carcass grades averaged 10.4 (10 = average Good), which were lower than in previous trials where exactly one percent level was fed daily over the trial (4[) . Following winter grazing at the Macon Ridge Branch Experi- ment Station, Winnsboro, Louisiana, steers were carried to slaugh- ter weight and grade using grazing or green chop with and without grain. The lots receiving the grain with the grazing and green chop were slaughtered following the trial. The steers receiving the forage without grain were fed 55 days in drylot following the 44 grazing and slaughtered. Grazing and green chop alone produced fewer pounds of gain than when concentrates were added to the treatments. Green chop fed alone produced the lowest gain while grazing with concentrates produced the highest daily gain. In the 55-day drylot trials, the highest daily gains were produced by the steers previously fed green chop alone. The majority of these steers graded in the Good grade with a few Choice and Stand ard in each treatment (5_) . We are now completing the third phase of a study comparing beef with forage alone, grain plus forage and drylot periods from 63 to 140 days. For two years, steers were marketed through one of the major chains and consumer acceptance evaluated. In trial 1, purchasers could not effectively distinguish in tenderness, flavor and juiciness between grass fed beef and beef from animals fed up to 108 days in feedlot. The highest percentage of con- sumers willing to repurchase at a higher price chose the forage fed beef (6) . In phase 2, animals were slaughtered at a younger age and the forage fed animals were lighter and not carrying the finish as in phase 1. They were marketed in the fall instead of in February. The drylot steers were fed 70 or 140 days and produced higher quality carcasses with a greater percentage grading Choice than the forage fed or grain on grass lots. On the basis of cut- ability and quality, the 70-day treatment produced the most de- sirable carcasses. Results from the retail consumer ratings showed differences among treatments for tenderness and flavor. The 70-day feedlot steers received the best ratings, while the forage steers received the poorest ratings (7_) . Most of the animals in phase 3 have been slaughtered. The four treatments used were (1) forage alone, (2) grass plus one percent grain for 232 days, (3) grass to 850 - 70 days in drylot, and (4) grass to June 1, one percent grain added 60 days, then drylot to 1050 pounds. All treatments weighed approximately 1050 pounds when slaughtered. Carcass grades were as follows: Lot 1 1 Choice, 5 Good, 1 Standard plus; Lot 2-7 Choice, 7 Good; Lot 3-10 Choice, 3 Good, 1 Standard plus; and Lot 4-2 Prime, 8 Choice, 3 Good, 1 Standard. The last seven grass steers will be slaughtered in April. LITERATURE CITED (1) Carpenter, J. C., Jr. and Brown, Paul B. 1966. Feeding Beef Calves From Weaning to Market. La. Agric. Expt. Sta. Bui. 612. (2) Roark, C. B., Harris, H. E. , Feazel, J. I., and Carpenter, J . C . , Jr . 1969. Annual Progress Report. West Louisiana Experiment Station, Rosepine, Louisiana. (3) Carpenter, J. C., Klett, R. H. , Brown, P. B. , and Robertson, G. 1968. Producing Quality Beef With Grass and Grain. La. Agric. Expt. Sta. Bui. 627. 45 (4) Carpenter, J. C., Klett, R. H. , and Hembry, G. 1971. Producing Slaughter Steers With Grain Self-fed On Pasture. La. Agric. Expt. Sta. Bui. 659. (5) Carpenter, J. C., Jr., Klett, R. H. and Phillips, S. 1969. Producing Slaughter Steers With Temporary Grazing Crops and Concentrates. La. Agric. Expt. Sta. Bui. 643. (6) Schupp, A., Bidner, T. , McKnight, W. , Carpenter, J. , and Smith, D. 1976. Consumer Acceptance of Forage Finished and Limited Grain Finished Beef. La. Agric. Expt. Sta. D.A.E. Research Report No. 503. (7) Schupp, A., Bidner, T. , McKnight, W. , Carpenter, J. , and Smith, D. 1976. Consumer Acceptance and Feasibility of Production of Forage Finished and Limited Grain Finished Beef. La Agric. Expt. Sta. D.A.E. Research Report No. 509. 46 USE OF LIMITED GRAIN FOR FINISHING STEERS ON PASTURE By Maurice L. Ray and A. E. Spooner Research has been conducted for several years at the Arkansas Anri cul- tural Experiment Station relative to various aspects of backgroundinn and/or finishing steers on pasture usinq a minimum of nrain. Current Arkansas research concerninq the use of limited nrain for finishinq steers on pasture is being conducted at two locations. Research at both stations involves back- qroundinq and finishinq fall born beef steers weaned in late summer. These steers are subsequently backgrounded through the fall and winter months (about 180 days) and then finished on pasture as lonn yearlings during the sprinn and early summer (60 to 80 days). Dr. Spooner and I plan for each study to span a minimum of four years to minimize the bias in data imposed by unusual seasonal weather variations. The past two years have certainly borne out the need for additional years as rain- fall patterns have been quite erratic. Today rather than present detailed data, some of which we would consider incomplete, I would like to discuss in general factors Dr. Spooner and I consider to be paramount for successful finishinq of younq beef animals on pasture. Perhaps these can elicit some discussion amono participants of this conference that will be helpful to everyone . First, forage species and combinations must be carefully selected and managed. As an example, tall fescue and white clover although not equal in quality to wheat, rye, ryegrass and arrowleaf clover combinations as measured by average daily steer gains has produced more gains per acre than the annual small grains due to greater grazing days and carryinn capacity. We have experienced considerable difficulty at our Beef Substation in East Central Arkansas in getting small grains seeded early enough to obtain sufficient growth to give more than 30 to 45 days fall grazinn before the steers must be moved to another feeding regime for the remainder of the winter. Fescue and clover has Generally carried steers at least 30 days farther into the winter. Another example, ryegrass alone or with white clover has been very erratic for us; often providing almost no fall and winter growth. It has often pro- duced very well in spring and early summer; however, at this time of year it is not difficult to obtain gains of three pounds or more per day on most of our pastures if supplemented by grain. Second, we have satisfied ourselves completely that we cannot finish modern beef steers, many of whom contain "exotic beef breeding", at under 24 months of age unless grain is fed on grass. 47 It has become obvious to us that the hiqher percentage of the blood of j the major British breeds the hiqher the percentage of choice carcasses we obtain. Third, animal selection and management is highly important to success in finish inn steers on grass particularly within the farmework of our studies. Calves started at under 500 pounds have been much more difficult to fatten to choice finish on grain and grass than calves started at 550 to 600 pounds. Fourth, in the backnrounding phase we have found a tendency on our part to leave the calves on pasture too long in the fall. Frequently the last two or three weeks of fall grazing has resulted in a loss of much of the weight that had been gained previously. Fifth, regular internal parasite treatment ( approximately every 90 days) has been very important to us. lie have found that the burden of internal parasitism has often reduced gains even though clinical signs of parasitism have been minimal or absent. Sixth, excessive clover growth in the spring of 1976 apparently contrib- uted significantly to a very high percentage of carcasses with objectionable yellow fat. At least these two phenomena occurred at the same time in 1976 and has caused us to go back to the literature and to initiate plans to study ‘ possible cause and effect relationships in this regard. Carcasses produced in 1976 were the first to have objectionable levels of yellow fat that we have encountered since our studies of finishing steers on grass began in 1965. Seventh, data obtained from the first two years of a study at the South- < ; west Branch Station (Hope) in which we have varied the time grain feeding was started and the level of grain fed to steers on tall fescue and clover inter- seeded into bermudagrass sod have indicated to us that grain supplementation at the level of .5% of live weight will not ni ve adequate backgrounding gain. The level of 1.0% throughout the entire backgrounding period has produced greater total gain than withholding grain the first half of the backgrounding | period and then giving 2.0% during the final 90 days prior to the finishing period. It must be pointed out, however, that the fall seasons have been drier than usual in both years, lie believe that with adequate moisture grain : supplementation may not be necessary for the first 90 days of the fall and early winter backgrounding period. 48 CONTROL OF INTERNAL PARASITES IN ANIMALS ON PASTURES By H. Ciordia Domestic animals are subject to parasitism by many species of parasitic nematodes. The extent of parasitism is determined by a number of factors such as weather, pasture and grazing management, and the physiology and condition of the animal. Knowledge of epizootiology of nematode parasites is necessary in order to develop a broad control program. Unlike bacterial infections, nematode parasites of domestic animals cannot multiply within the host; each generation must undergo some development outside the host before reentering and once again adopting a parasitic existence. The role of internal parasites in the economy of livestock production can be measured by the estimated losses attributable to the depredation of these pests. In a recent publication by the U. S. Department of Agriculture, the annual loss due to mortality and morbidity caused by internal parasites was estimated to be over $162 million (1). Parasitism is significant in young or poorly managed livestock. Under farm conditions, parasitism exists primarily subclinically and, therefore, produces unnoticed economic losses. The economic losses or costs per cattle farm reported from South Georgia (3) in 1962 were $570 for sickness, $977 from death, and $121 for anthelmintic medications, a total annual cost of $1,668 for internal parasites per beef cattle farm. Of even greater concern are the results of a survey conducted in Georgia which indicated that parasitism has increased steadily during the last 15 years (2). The prevention of parasitic infection is primarily a management problem based on the available knowledge of the life cycle of the round worms . The life cycle chain is most easily broken at its weakest link -- in this parasite, the free -living stages. Treatment of the host animal with chemicals is therapeutic, not preventive. To break the life cycle, management must have knowledge of some of the field factors, such as temperature and moisture, which are necessary for development, migration, and survival of the larvae. The larvae in Georgia are provided with adequate temperatures for development during most of the year. On the basis of available knowledge, some management factors must be used in an attempt to reduce parasitism. Pasture Management Overstocking . With improved pastures , the tendency is to concentrate more cattle per acre and thus increase the amount of cattle droppings and the potential parasite load of the pasture. Our work has shown that increasing the concentration of cattle on improved pasture resulted in greater parasite 49 contamination of the pasture and greater infection of grazing animals (8). Thus, average daily weight gains (A.D.G.) and carcass grades were lower in cattle from overstocked pastures than in cattle from moderately stocked or understocked pastures (Table 1). Overstocking will result in overgrazing, which will bring about a more rapid increase of the round worm population. But overstocking is not considered to be as significant as nutrition. We can say, with reservation, that if the nutritive value of the improved pasture is much better than that of the unimproved pasture, then increased stocking rate does not necessarily result in clinical signs of parasitism. Overgrazing. Close grazing results in heavier infections of parasites because grazing cattle will pick up greater number of parasitic larvae, which are usually concentrated on the bottom 5.8 centimeters of the pasture grass. When the pasture is short and scarce , the cattle will spend more time grazing to consume the required amount of food. This factor will increase the possi- bility of ingesting more larvae because cattle will graze during the periods of optimum larval migration, which coincide with an increase in the humidity from dew deposits on grass blades or with actual rain. Also, in short forage pasture, cattle will graze a much larger area in order to satisfy their food requirements. This type grazing will also increase their opportunity to pick up infective larvae. Furthermore, to be ingested, the larvae need to climb a much shorter distance on the short grass than on forage of average height. The above observations may be complicated by several .factors . For example, in hot, dry weather, a closely grazed pasture may result in greater kill of either parasite eggs or larvae, or both, because of increased heat and evaporation. Consequently, in theory, overgrazing may be a desirable parasite control practice, whereas high forage may protect the eggs and larvae during the summer. Moreover, grass allowed to grow too tall, especially if it goes to seed, has low nutritive value, which may make the animals more susceptible to parasitism. As grass grows taller, particularly in continuously grazed pasture, cattle searching for more succulent, palatable grass tend to confine their grazing more and more to areas that have previously been grazed closely. Consequently, these cattle may pick up more parasites from an undergrazed pasture than from one more closely grazed over its entire area. Studies conducted at the Georgia Experiment Station (4) clearly showed that cattle on an overgrazed pasture had many more roundworms when slaughtered, made lower A.D.G. , and had lower carcass grades than those on a moderately grazed or undergrazed pasture (Table 2). These results point out the poten- tial epizootiological danger of overgrazing pastures. This danger is increas- ed when the nutritive value of the forage is below the required level. In our 3-year study, nutritive values of the forages was not below the required level. Rotation of animals on pasture. Because of the continuous buildup of larval parasites, permanent pastures can promote a high level of parasite in- fection in stock grazed on them, especially bermudagrass and fescue grass pastures. Larvae can survive for longer periods in these grasses than in others, probably because of the protection afforded by the thick matting of these grasses. The area used as a permanent pasture probably should be divided into sections to be grazed rotationally , and thus allow the undergrazed sections to "rest". In theory, this resting may aid in the control parasites and provide more nutritive forage. The length of the resting period for each dection depends on weather conditions. For example, in the summer, a relative- ly short resting period will usually suffice, for the larvae will succumb to 50 the heat and to dry conditions more quickly then than during other seasons . The rotation of animals probably is not as critical on a temporary pasture as on a permanent one. Temporary pastures entail plowing that should eliminate more parasite eggs or larvae that may have been present. A resting or non-contaminated period also is provided. We have found very little larval carryover from one grazing season to the next on temporary pasture. In addit- ion to this low carryover the temporary forage usually provides high quality nutrition, that in itself is a good control of parasites. Three tests conducted during 3 consecutive years in Georgia (7) showed that rotationally grazed beef steers had the largest number of internal parasites whereas the continuously grazed steers, on the same type of winter temporary pasture, had the lowest number of worms. Continuous grazing consistently resulted in higher A.D.G. than did the rotational grazing; how- ever, rotational grazing resulted in higher stocking rates, higher gains per hectare, larger numbers of round worms, greater net return, and less cost per unit of gain than did continuous grazing (Table 3). If infected animals are to be moved to a clean pasture, a good practice is to treat them for parasites before transfer. This treatment will delay the contamination of the new pasture. Soil preparation. Nematode larval population of pasture is reduced by turning the land (plowing or disking). This measure is especially advanta- geous in permanent pastures such as bermudagrass and fescue. The round worm population is lower in animals grazing renovated fescue than in those grazing a permanent fescue pasture. Also, harrowing or dragging contaminated pastures possibly aids in the destruction of larvae because the piles of manure are scattered and dry faster. On the other hand, in rainy or cool seasons, scattering manure droppings may actually spread the infective larval stages. Pasture fertilization. The amount of forage available for grazing cattle is dependent, along with other factors, on the amount of fertilizer applied to the pasture. Results in an experiment in cooperation with the Southern Piedmont Conservation Research Center, Watkinsville , Georgia, indicated that fertilization increased the amount of forage available, which, in turn, decreased the level of parasitism in cattle. Use of poultry litter on pastures. Two tests in Watkinsville, Georgia showed that parasitism in cows and their calves on tall fescue pasture fertilized with poultry litter was lower than parasitism of cattle on fescue fertilized with NH4NO3. Evidently, poultry litter may be used on pastures without epidemiological implications. This practice may provide cattle growers with a profitable practice , with important ecological benefits to poultry growers . Animal Management Nutrition . Of all the preventive measures available, proper nutrition is probably the most important. In our experimental studies, no serious parasite problem was met as long as the cattle were on an adequate plane of nutrition. Enough pastures for grazing animals or for supplemental feed must be provided. Sufficient nutritionally balanced feed is the best treatment for parasitism probably because of the interaction of nutrition and host resistance. The species and type of grass and the quality and quantity of the available pasture can influence the parasite population of grazing animals . Our work (5) has indicated that calves on pastures with different species of 51 to grass differ in the number of internal parasites recovered (Table 4). More roundworms have been found in calves on fescue grass than in those on rescue grass, ryegrass, crimson clover, or a winter temporary mixture (rye, wheat, ryegrass, and crimson clover). Also, more infective larvae were recovered from grass clippings from fescue pastures than from clippings from comparable pastures planted with a temporary winter mixture or with ryegrass -crimson clover (10). In each of the experiments, the nutritional level provided by each forage probably was an important factor in the difference between the performance and round worm populations of the groups of calves. The combined effects of the lower nutritive value of fescue and the greater round worm population produced lower weight gains in the animals . Supplemental feeding of calves on pasture is advantageous in reducing the danger of parasites among calves. In an experiment conducted at our station, a corn supplement increased the weight gains and the carcass grades \ and reduced the number of nematode parasites in beef yearlings (Table 5). Earlier tests (9) also showed that calves given corn supplement while on three types of pastures generally had fewer round worms than those on the same type of pasture without corn supplement. The difference was especially noticeable in the groups on fescue (Table 6). In other experiments, a corn supplement significantly inhibited develop- ment of eggs and larvae of cattle nematodes in feces (6). Thus, corn has a twofold effect on parasitism: (l) it increases the nutritional level to provide the host with the immunological tools to fight the invasion; and (2) it reduces the seeding of the pastures with infective larvae. In addition to the nutritional effect of the various pastures on parasitism in calves, pastures may differ in their direct effect on the development, survival, and migration of the free-living stages and in their indirect effect on the development of the parasitic stages of the nematodes. For example, the type of forage growth may facilitate or inhibit larval migration, whereas the height or density of the forage affect the adequacy of protection provided the larvae against the vagaries of weather and may control! developmental rate and survival. Mixed grazing. Animals of different ages should not be grazed together because younger calves are more susceptible to phrasites than are older animals. The incidence of roundworm infections is low in calves 2 to 3 months; old, probably because of their lack of exposure, because milk comprises most of their diet and forage comprises very little. The number of infected animals increases rapidly up to 9 months of age and then apparently more slowly until just about all are infected. Under proper management and nutrition, the incidence of round worms decreases after cattle are 18 months old . exp few (5 (6 Health . Diseased animals are more susceptible to parasitic infections than are healthy animals; consequently, cattle should be maintained in good health. Sanitation . Because the eggs and larvae of parasites are found in the manure, an effort should be made to prevent its accumulation in barns, in shed: and around watering places. Inheritance . Some workers (11) have shown that by selective breeding we may be able to create populations of cattle resistant to some internal parasites. However, tested resistant animals are not readily available on the market . Host resistance. Generally, pastures free from parasitic larvae would (7 (f 52 seem desirable; however, cattle can and do develop some degree of resistance to these parasites if the animals are not exposed to many larvae. When later exposed to infective parasitic larvae, such partly-immunized cattle will have fewer round worms than do cattle with no previous parasite exposure. Treatment When control of parasitism through prevention is not practical, the animals should be treated with anthelmintic (de-wormer) drugs. Treatment alone cannot be relied on to check outbreaks or to cure weakened animals. Treatment is most efficiently used as an adjunct to other control measures rather than as a substitute for them. Parasitism is essentially a herd disease rather than a condition of one or several animals although some individual animals may be more resistant and others more susceptible to parasitism. LITERATURE CITED (1) Losses in Agriculture, Agricultural Handbook No. 291. USDA, ARS 1965: 79 pp . (2) Becklund, W. W. 1959. Worm Parasites in Cattle from South Georgia. Vet. Med. 54:369-372. (3) Becklund, W. W. 1962. Helminthiasis in Georgia Cattle -- A Critical and Economic Study. Am. J. Vet. Res. 23:510-515. (4) Ciordia, H. , Bizzell, W. E., Vegors , H. H. , Baird, D. M., McCampbell, H. C. , and Sell, 0. E. 1962. The Effect of Three Grazing Intensities of Winter Temporary Pasture on Internal Parasitism of Beef-Type Yearling Cattle. Am. J. Vet. Res. 23:15-20. (5) Ciordia, H. , Bizzell, W. E., Baird, D. M., McCampbell, H. C. , Vegors, H. H. , and Sell, 0. E. 1962. The Influence of Pasture Type and Supplemental Grain Feeding on Number of Gastrointestinal Nematodes in Beef Yearlings. Am. J. Vet. Res. 23:1001-1006. (6) Ciordia, H. and Bizzell, W. E. 1963. Effect of a Grain Diet on Development of Some Cattle Nematode Larvae. J. Parasitol. 49 (5 Sec. 2): 44. (7) Ciordia, H. , Bizzell, W. E., Baird, D. M., McCampbell, H. C. , and White, P. E. 1964. Effect of Rotational Grazing Systems on Gastrointestinal Nematodes in Beef Yearlings. Am. J. Vet. Res. 25:1473-1478. (8) Ciordia, H. , Neville, W. E., J., Baird, D. M., and McCampbell, H. C. 1971. Internal Parasitism on Beef Cattle on Winter Pastures: Level of Parasitism as Affected by Stocking Rates. Am. J. Vet. Res. 32:1353-1358. 53 (9) Vegors, H. H. , Sell, 0. E., Baird, D. M., and Stewart, T. B. 1955. Internal Parasitism of Beef Yearlings as Affected by Type of Pastures, Supplemental Corn Feeding, and Age of Calf. J. Animal Sci. 14:256-267. (10) Vegors, H. H. , Smith, W. N., Baird, D. M . , Ciordia , H. , Bizzell, W. E. , and Sell, 0. E. 1958. Phenothiazine Treatment of Yearling Beeves on Winter Pastures. Am. J. Vet. Res. 19:805-810. (11) Whitlock, J. H. 1955. Tr ichostrongylidosis in Sheep and Cattle. Proc. Am. Vet. Med. Assoc. 92:123-131. TABLE 1. --Effect of Three Stocking Rates on Parasitism of Yearling Calves on Winter Temporary Pastures (3-Year Average). A . D . G . * Carcass Av. no. Stocking rates (kg) grades** worms Understocked pasture 1.02 10.6 ” 5,330 (1.0 calves/acre) Moderately stocked pasture 0.91 9.5 26,979 (1.25 calves/acre) Overstocked pasture 0.85 9.0 38 ,429 (1.50 calves/acre) *A. D.G. = Average daily gain “‘■■'Average : Good = 10, choice = 13. TABLE 2. . --Effect of Three Grazing Intensities on Parasitism of Yearling Calves on Winter Temporary Pastures (3-Year Average). Over- Moderately Under- grazed grazed grazed Item pastures pastures pastures Average stocking rates 2.53 1.90 1.37 A . D . G . * (kg) 0.70 0.85 1.08 Carcass grades** 6.14 6.86 7.57 Average No . roundworms 164,831 62,629 30,027 *A.D.G. = Average daily gain. ■“‘‘'■'Averages: Standard = 7, Good = 10. 54 TABLE 3. --Effect of Continuous vs. Rotational Grazing of Yearling Calves on Winter Temporary Pastures. Continuous Rotational Item grazing grazing Av. stocking rate (ha) 2.67 3.61 A.D.G.* (kg) 1.07 0.93 Gain/hectare (kg) 469 5 31 Average no . round worms 23,092 37,691 Return/hectare, $ 115.97 159.19 *A.D.G. = average daily gain TABLE 4. --Effects of Pasture Types on Parasitism and Weight Gains of Yearling Calves . Renovated Temporary Fescue fescue Item .pasture pasture pasture No. round worms/calf 70,964 83.609 30,211 A.D.G. * (kg) 0.70 0.48 0.72 Stocking rate (ha) 3.46 2.77 2.57 *A.D.G. = average daily gain TABLE 5. --Effects of Two Types of Winter Pastures and Supplemental Feeding on Parasitism and Weight Gains on Beef Yearling Calves. Temporary pasture Res cue grass pasture Item No corn corn No corn corn A.D.G.* (kg) 1.16 1.31 1.40 1.51 Carcass grade 7.00 7.38 7.00 7.57 Av. no. worms 50 ,126 16,216 30,345 14,439 A.D.G. = average daily gain 55 TABLE 6 . — Effects of Supplemental Feeding and Three Types of Winter Pasture on Parasitism and Weight Gains of Yearling Beeves (2-Year Average). Type of pasture Fescue Temporary Crimson clover No corn corn No corn corn No corn corn A.D.G.* (kg) 0.63 1.04 1.20 1.21 1.08 1.07 A v . no . worms 75,250 21,000 13,500 3,500 24,250 7,500 *A.D.G. = average daily gain / 56 CURRENT STATUS OF INFRARED REFLECTANCE By J. S. Shenk and R. F Barnes The need for a method to evaluate forage quality that is rapid, inexpen- sive, accurate, and precise has long been recognized (1 ) . The use of near infrared reflectance spectroscopy to predict the chemical and nutritional composition of forage and feed grains has been proposed (2, _3 , _4, 5). The information reported thus far for forages has been obtained with infrared spectro-computer systems (IRSCS) . These systems use a scanning monochromator capable of taking measurements at as many as 8,000 different wavelengths in the region from 1,0 to 2,6 ym. Commercial instruments do not have this capac- ity, Newer models being developed will have the capability to take measure- ments at more wavelengths. The purpose of this paper was to assess the effectiveness of the wave- lengths (filters) proposed for cereal grains or forages (2) to predict various quality components in forages and feedstuffs. IRSCS analysis with multiple wavelengths was included for comparative purposes. MATERIALS AND METHODS A wide range of feedstuffs grown at different locations and in different years was chosen for this study. Samples were prepared for analysis by dry- ing to 92 to 95 percent dry matter and grinding through a 1 mm screen in a Wiley Mill. Samples were analyzed in duplicate by the Kjeldahl procedure for nitrogen and converted to percentage protein by the appropriate factor. Digestibility was estimated by the _in vitro procedure. Procedures for collecting the animal data for the forage samples have been reported (2_, 6) . Reflectance data were collected by monochromator every 20 A between 1.05 to 2.55 ym for each sample (a total of 751 data points). Forage samples were analyzed by IRSCS in duplicate with single determinations for the cereal grains. Infrared (IR) data were recorded and analyzed as log (1/R) , where R equals reflectance. Data were averaged for each sample and used for cali- bration. The IR data from the six wavelengths proposed for grains (1.68, 1.94, 2.10, 2.18, 2.23, 2.31 ym) or forages (1.672, 1.70, 1.94, 2.10, 2.18, 2.336 ym) were then used to develop calibration equations for each group of samples. Some bias may be associated with this simulation of commercial instrument filters, but we believe these results are useful for general comparisons . Wavelengths for the IRSCS comparison were selected by multiple stepwise regression and added or deleted from the calibration equation on the basis of a partial F test. The minimum value selected to prevent wavelength additions by chance was 8.0. Standard deviations for protein and in vitro digestion of 57 TABLE 1. — Comparison of simulated protein and in vitro digestion calibration of forages and cereal grains when commercial wavelengths and the spectro-computer were used Feedstuff Sample No. Protein In vitro Digestion^ a—/ SEC—/ R2 a2/ 3/ SEC— R2 4/ Temperate forages— 117 5.15 8.07 Grain filters 0.79 0.98 3.27 0.83 Forage filters 0.79 0.98 2.79 0.87 Spectro-computer 0.69 0.99 1.89 0.95 Tropical grasses—/ 29 4.45 11.01 Grain filters 0.95 0.96 5.25 0.82 Forage filters 0.99 0.96 3.23 0.93 Spectro-computer 0.62 0.98 1.46 0.99 Corn silage—^ 91 1.27 2.29 Grain filters 0.52 0.84 1.86 0.35 Forage filters 0.48 0.87 1.56 0.53 Spectro-computer 0.40 0.91 1.36 0.62 Corn grain — / 61 0.69 2.77 Grain filters 0.24 0.89 2.31 0.46 Forage filters 0.24 0.89 2.09 0.61 Spectro-computer 0.21 0.91 1.73 0.62 Oats-^/ 67 1.54 3.31 Grain filters 0.47 0.92 1.73 0.75 Forage filters 0.49 0.91 1.50 0.81 Spectro-computer 0.42 0.92 1.39 0.84 Wheat—/ 55 2.30 1.17 Grain filters 0.35 0.98 0.81 0.37 Forage filters 0.38 0.98 0.78 0.38 Spectro-computer 0.37 0.98 0.76 0.39 Barley—/ 31 1.46 1.73 Grain filters 0.49 0.91 1.43 0.45 Forage filters 0.44 0.93 r.44 0.44 Spectro-computer 0.25 0.98 1.14 0.59 1/ Digestion of tropical grasses was estimated with a 72-hour hn vitro organic matter disappearance procedure. All other samples were analyzed by the ini vitro dry disappearance procedure, a = Standard deviations of all samples. SEC = Standard error of calibration. Samples provided by R. F Barnes and W. N. Mason Samples provided by J. E. Moore Samples provided by J. E. Baylor Samples provided by J. H. McGahen Samples provided by H. G. Marshall Samples provided by R. P. Pfeifer matter 2/ 3/ 4/ 5/ 6/ 7/ 8/ 9/ 58 each crop are found in Table 1; similar data for animal measurements are shown in Table 2. RESULTS AND DISCUSSION Comparisons of the calibration statistics for forages indicate that both the grain and forage wavelengths can be used to predict forage protein (Table 1). This is because the protein reference wavelength, 2.10 pm, and the protein wavelength, 2.18 pm, were used in both calibrations. However, the in vitro digestion standard errors of calibration (SEC) and the corresponding R^" values are consistently better for the forage wavelengths than for the grain wavelengths when the 1.672 pm wavelength is substituted for 1.68 pm, the 1.70 pm for 2.23 pm, and the 2.336 pm for 2.31 pm. Protein calibration statistics for cereal grains are slightly larger than those reported by Williams (7) because calibration was accomplished over a wide diversity of locations and growing conditions. Nevertheless, both forage and grain wavelengths gave very similar results, an indication that the three wavelengths that differed among these sets did not interfere in the calibration. The oat samples exhibited the largest standard deviation in digestibility for grains, and here again the forage wavelengths had a con- sistently lower SEC and higher r2. Results with IRSCS suggest that some lowering of standard errors can be accomplished by adding additional wavelengths to predict each constituent. IRSCS calibrations contained from 3 to 10 different wavelengths for each constituent and group of samples. The prediction of animal response with the forage wavelengths was not very acceptable (Table 2). However, the spectro-computer results indicated that further improvement in prediction will be possible if more appropriate wavelengths are chosen to predict animal performance as has been shown with protein and _in vitro digestion. Also, tropical forages may require a differ- ent set of wavelengths though compromise wavelengths may be found that will be acceptable for both temperate and tropical forages. The biggest problem is obtaining enough animal data over locations, species, varieties, and growing conditions to determine the appropriate wavelengths. To test the size of the standard error of predicting the protein and digestion of samples not used in the calibration, we split the temperate for- ages and all of the 214 grain samples into two equal size groups on an every other sample basis. The first group was used to derive the calibration (C) equation, the second to test the equation (P) (Table 3). The general agree- ment between C and P indicates the accuracy of the calibration equation in predicting the protein and digestibility of these crop species. Also, cali- brations of grains within species appear to be more accurate than across species . CONCLUSION The results suggest that properly calibrated instruments fitted with six wavelengths (1.672, 1.70, 1.94, 2.10, 2.18, 2.336 ym) should be able to 59 TABLE 2. — Comparison of simulated intake (I), digestibility (D) , and digestible 'CT G 5-i o CNJ 1 — 1 NO > CU CN 00 ON ON ON 4-1 Pi » o • « (U ' — i 1 o ON -3 e> • • cx 4-) cu cu 13 -3 G CO G 5-i CO i o CU ON co GO UO • m GO CN in r-- 00 co CO Pi . . • . G • C 5-1 o o o o i — 1 3 o O CX O CO G •H Mh E •H G G 4-1 G 4-4 3 O CO 5-i CO G G O 5-1 O CMl CO • G ■H •H 4J G > > C 13 13 o O •H G G G 13 G CX cx -- — 1-4 G G 13 ml G — G G 3 CO CO CO co 4-1 e GO 4-1 E •U E E 5-4 r— f o G i— 1 o C/3 II G G CO O •rl o G -H o co CO a) >4-4 <4-4 i O <4-4 i II CJ) GO o <4-4 o w CN ON cO G G 5-4 G G to C/3 NO CN 5-1 4J GO 4J r-l 00 4J o G G o G G U Pm 5-i 5-i G O G G rH CN m|- Ct| 0) O cx •H O CX CX Pm c n CX Pm c/3 E O CU G H H 60 TABLE 3. — Comparison of the statistical errors associated with temperate forage and cereal grain samples used for calibration (C) and prediction (P) of protein and in vitro digestion Feedstuff s Sample No. A7 Forage SE— / Wavelengths Spectro- SE— ^ •Computer RZ Temperate forages Protein C 59 5.42 0.89 0.97 0.78 0.98 P 58 4.89 1.00 0.96 0.85 0.97 In vitro 3 / digestion^-' C 59 8.32 3.15 0.87 1.96 0.95 P 58 7.96 3.37 0.83 2.45 0.92 Cereal grains Protein C 107 2.71 0.73 0.93 0.44 0.98 P 107 2.71 0.77 0.92 0.55 0.96 In vitro digestion—' C 107 9.76 2.24 0.95 1.95 0.97 P 107 10.11 2.44 0.94 2.10 0.96 — a = Standard deviation of samples — , SE = Standard error 3 — ' In. vitro digestion was estimated with the jin vitro dry matter disappearance procedure. 61 predict the protein of cereal grains with a standard error between 0.2 and 0. 5 percent, and predict in vitro digestion with a standard error of <2.0 percent. The standard error of prediction of forage protein would be approximately 1.0 percent, and that for in vitro digestion between 2.5 and 3.3 percent. Standard errors of this magnitude will be useful for some but not all applications. Prediction of animal response will require further refinements in instrumentation and selection of wavelengths. LITERATURE CITED 1. Barnes, R. F. 1973. Laboratory methods of evaluating feeding value of herbage. Ch. 32, Vol. 3, pp. 179-214. In: G. W. Butler and R. W. Bailey (eds.). Chemistry and Biochemistry of Herbages. Academic Press, New York. 2. Norris, K. H., R. F. Barnes, J. E. Moore, and J. S. Shenk. 1976. Pre- dicting forage quality by infrared reflectance spectroscopy. J. Anim. Sci. 43:889-897. 3. Shenk, J. S., W. N. Mason, M. L. Risius, K. H. Norris, and R. F. Barnes. 1976. Application of infrared reflectance analysis to feedstuff evaluation. First International Symposium on Feed Composition, Animal Nutrient Requirements, and Computerization of Diets. Utah State University, Logan, Utah. 4. Shenk, J. S., M. R. Hoover. 1976. Infrared reflectance spectro-computer design and application. 7th Technicon International Congress, New York, N.Y. 5. Shenk, J. S. 1977. The role of plant breeding in improving the nutritive value of forages. J. Dairy Sci. 60:300-305. 6. Ventura, M. J., J. E. Moore, 0. C. Ruelke, and D. D. Franke. 1975. Effect of maturity and protein supplementation on voluntary intake and nutrient digestibility of Pangola Digitgrass hays. J. Anim. Sci. 40:769-774. 7. Williams, P. C. 1975. Application of near infrared reflectance spectroscopy to analyses of cereal grains and oilseeds. Cereal Chem. 52:561-576. 62 BREEDING STOCKS AVAILABLE AT REGIONAL PLANT INTRODUCTION STATIONS By W. R. Langford Abstract Upon passage of the Research and Marketing Act in 1946 four regional plant introduction stations were established in the United States to support the regional new plants projects. These stations are operated cooperatively by the State Agricultural Experiment Stations and the Agricultural Research Service. Although plant introduction in the United States dates back to the colonial period and the present Plant Introduction (P. I.) numbering system to 1898, prior to 1946 there was no organized program to maintain materials after introduction. Since 1946 the four regional stations have accumulated 105,000 accessions representing more than 700 plant genera and several thousand species. Although our country is deficient with respect to native crop plants, plant breeders in the United States now have easy access to a greater diversity of germplasm than do their counterparts in any other country Sizable collections of most forage crops grown in this country are held at one of these four stations. Some collections held at Experiment, Georgia are: bluestems, Cenchrus , Chloris , Cyndon , Digitaria , Panicum , Paspalum, annual Trifolium spp . , Medicago , and Vicia . The Northeastern Regional Station maintains perennial Trifolium spp., Lotus, and Phleum. Perennial Medicago spp Bromus , Melilotus , and Coronilla are held at Ames, Iowa; and the Western Regional Station maintains Festuca , Dactylis , Lolium, Agropyron, and Eragrostis ♦ Propagating material of all of these is available to plant scientists upon request. Through plant exploration and international exchange of plant germplasm new introductions are added to these collections annually. Explorations will be conducted this year to collect (1) grasses in the U.S.S.R.; (2) clovers in Greece, Yugoslavia, and Italy; and (3) Leucaena in Mexico and Central America. When there is need for additional germplasm, requests for explorations should be submitted in project outline form to the S-9 Technical Committee. Requests from all 4 regions are reviewed at the national level by the ARS Plant Germplasm Coordinating Committee. Proposals that are approved by the ARS committee are recommended on a priority basis for funding. 63 POPULATION IMPROVEMENT BY RECURRENT RESTRICTED PHENOTYPIC SELECTION By Glenn W. Burton Population improvement involves increasing the frequency of desirable genes. To accomplish improvement: 1. The initial population must have a desirable-gene-frequency of less than 1.0. 2. The desirable genes must be identifiable. 3. Individuals carrying desirable-genes must be selected for the next generation . 4. To avoid inbreeding depression, a large number of unrelated plants carrying desirable genes must be intermated in each generation. Mass selection is the oldest method of population improvement. Early man, without knowledge of genetics, used it to develop our crop plants from their wild progenitors. Mass selection involves isolation of desirable genes on the basis of their phenotypic expression. Highly heritable characters, suchj as maturity respond to phenotypic selection more rapidly than yield, a charac- I ter that usually has a low heritability . Recurrent restricted phenotypic selection (RRPS) is an improved modifica- tion of mass selection as generally practiced (Burton, 1974). With four two- year cycles of RRPS, we were able to advance the forage yield (in replicated seeded plots) of Pensacola bahiagrass a mean of 17.7% - 2% per cycle for the previously selected narrow-gene population and 6% per cycle from the unselected wide-gene population. The variances remaining in the populations indicate that forage yields can be further increased with additional cycles of RRPS. The six restrictions in RRPS that improve the efficiency of mass-selection for yield improvement are as follows: 1. When possible we choose germplasm with a high degree of self- incompatability but good cross-compatability to reduce the likelihood of selfing. This restriction (normal in Pensacola bahiagrass) is good but not necessary. ! 64 2. We divide the 1000-plant spaced population into 25-plant square plots and select the best five plants in each plot to reduce soil hetero- geneity effects and faciliate visual selection in lieu of taking forage yields . 3. Instead of using open-pollinated seed from the 200 selected pheno- types to plant the next cycle, we intermate them in isolation to pro- duce seed for the next generation. This procedure doubles the rate of advance by imposing paternal as well as maternal selection. 4. We greatly facilitate intermating and gene recombination by bringing together in isolation two culms (ready to flower the next day) from each phenotype. These culms, placed together in water in the labora- tory, are in such intimate association that agitation each day ensures maximum cross-pollination. 5. We use 2 culms from each selection to provide equal representation and ensure that each will be represented should one culm fail. 6. We keep the intermated seeds from each of the 2 00 selections separate and plant enough for 100 plants of each in a single row in flats of sterile soil in the greenhouse in December. When old enough to trans- plant, we pull the whole row and select the five largest plants to set in sterile soil in 5-cm clay pots. (It is well to have an extra plant potted to insure against loss). This procedure helps keep the gene base wide and gives a combined seedling spaced-plant population of 2 0,000 plants . A more detailed description of a single cycle of RRPS currently practiced in Pensacola bahiagrass improvement follows. One thousand 4-month old seedlings grown in 5-cm pots under uniform greenhouse conditions are transplanted .9 x .9 m apart in a uniform well pre- pared seed bed with a new transplanting tool that insures uniform depth and establishment (2). Green forage yields are taken at a uniform height either with a sickle bar mower or a riding rotary mower. Four men with the rotary mower, a cylindrical grass catcher made from hardware cloth on a long handle, a dial milk scale and a hardware cloth weighing pan can cut and weigh 1,000 plants in less than 8 hours. After two seasons of assessment, the five top yielding plants in each 5x5 plant block are selected and tagged with red merchandising tags identify- ing their location. Beginning at 8 a.m. , two culms with heads that will start flowering the next day are pulled to include some stolon from each tagged plant; these are tagged together and put in water. Culms from all 200 selec- tions are placed in containers of water (plastic gallon milk jugs with the top cut out but handle attached) and are grouped together on a laboratory table with a north window exposure. A large bag made from kraft wrapping paper to enclose the culms in the 12 milk jugs is suspended from the ceiling and left open at the bottom. Each morning as anthesis is in full sway, the bag cover- ing the heads is squeezed and opened rapidly to insure complete intermixing of the pollen shed from the 2 00 selections. After anthesis is completed on all heads, the bag is removed and the culms mature their crossed seed without 65 further treatment. Mature heads from each selection are threshed separately. In December when the next cycle is started, seeds of each selection are planted in a single 45 cm row with 5 cm between rows in 45 x 60 cm flats of uniformly fertilized steam-sterilized soil at rates to give about 100 seedlings per selection. When about a month old, the seedlings in each row are pulled, the five most vigorous seedlings are transplanted to 5-cm clay pots and the remainder are discarded. By combining seedling selection with field selection, it is possible to screen the 19,900 recombinant plant population necessary to allow the equivalent of one single chance recombination between each of the 200 selected clones. There is increasing evidence that the five top yielding plants in each 5x5 block could be selected by visual rating about as well as by actual weight . We have used a 2-year cycle and have saved 20% of the best plants. Our Pensacola bahiagrass study suggests that we might double the rate of yield increase by using a 1-year cycle and saving three or four rather than five of the best plants in each 25-plant block. To do this would not allow us to screen as well for winter injury or reactions that cannot be assessed in one growing season. The following procedure, however, allowed us to make pro- gress breeding for winter hardiness with a 1-year cycle in 1975. In April, 1976, we set plants .6 x .6 m apart to save land. The plants grew well but failed to produce enough heads at one time in the summer to make the labora- tory polycross. Therefore, we will be unable to complete the 1976 cycle until 1977 and it will become a 2-year cycle. The field number is kept with each 5-plant progeny until we are ready to set the population in the field — usually late April. By this time we will have additional information including a winter hardiness rating on the parent plants. If the parent of a 5-plant progeny fails to survive the winter, we can eliminate its 5 plants from the population to be set in the field. The paternal influence of these plants will remain in the population but by eliminating their maternal influence, we will improve the hardiness of the remaining population more than if they had been left in it. With this procedure, we can also eliminate the progeny of plants that performed poorly after the selections were put to- gether in the polycross. The five seedlings of each remaining selection are thoroughly randomized before they are set in the field for final evaluation. Literature Cited 1. Burton, Glenn W. 1974. Recurrent restricted phenotypic selection in- creases forage yields of Pensacola bahiagrass. Crop Sci. 14:831-835. 2. Burton, Glenn W. 197 6. Precise back-saving transplanter for small potted plants . Crop Sci. 16:732-734. 66 IDENTIFYING VIRUS RESISTANCE IN WHITE CLOVER BY APPLYING STRONG SELECTION PRESSURE. I. TECHNOLOGY By 0. W. Barnett and P. B. Gibson Virus diseases of clovers have been recognized for many years. A mosaic of red clover was reported by Elliot in 1921 (5) . Virus diseases of white clover (Trifolium repens L.) were described as early as 1935 by Zaumeyer and Wade (18) and by Pierce (14). By 1949, a virus disease of ladino white clover occurred extensively in the northeastern United States (10) . It was soon realized that viruses could severely reduce forage and seed yields of white clover (8, 9). The several viruses that infect white clover may be important in the failure of white clover stands to persist in pastures of the south- eastern United States (11) . It is difficult to give a detailed description of all the technology needed when approaching a task such as finding virus resistance in white clover. Some topics which are less familiar will be dealt with in more detail than others. This paper will also deal primarily with white clover but the princi- ples could be used with many other crops. VIRUSES THAT INFECT WHITE CLOVER As previously stated, several viruses occur in white clover. Indeed mul- tiple infections of two or three viruses are commonly found in naturally infected white clover. The following 13 viruses have been found in white clover: aphid transmitted - alfalfa mosaic (AMV) , clover yellow vein (CYVV) , pea streak, peanut stunt (PSV) , and red clover vein mosaic viruses; nematode transmitted - Arabis mosaic, strawberry latent ringspot, tobacco ringspot (TRSV) , and tomato black ring viruses; thrip transmitted - tomato spotted wilt virus; no known vectors - clover yellow mosaic, tobacco streak, and white clover mosaic (WCMV) viruses (1, 13). Identification of these viruses requires that several techniques be used because no single technique provides positive identification. As a minimum, host range and host reactions plus serology and/or particle morphology should be used. However, after the viruses found in a particular plant species from a given locality have been identified, a single technique is usually sufficient. CHOOSING VIRUSES FOR CONCENTRATED EFFORT Obviously, a breeding program cannot work simultaneously with all 13 viruses. First, find out which viruses occur in your area, state, or region. For example, Lucas and Harper (11) isolated AMV, CYVV, PSV, WCMV, and TRSV from white clover in North Carolina. In the clover plots at Clemson, South Carolina CYW and PSV are predominant with an occasional plant infected with AMV. 67 The next step in choosing viruses is to determine which of the viruses present are most prevalent. This can be done two ways. In established clover pastures the viruses should occur at random (1). These pastures can be sampled by collecting clover stolons at intervals diagonally across the pasture without regard for virus symptoms in the stolons. Another method of sampling for virus prevalence tells not only which viruses are most prevalent but also which viruses are transmitted most readily in the area. This method requires a newly established clover plot or pasture. Again samples should be taken at random without regard for symptoms, but more samples will be required to find low levels of infection. If the clover is sampled several times at intervals a more complete picture of virus spread and prevalence can be obtained. The white clover plants collected by our survey of several southern states, i conducted by the first method described, contained AMV, CYVV, PSV, and WCMV (1). Based on the total number of plants collected PSV was the most prevalent virus followed in order by CYVV, AMV, and WCMV. However, if prevalence is based on the number of pastures surveyed CYVV and PSV were about equal in prevalence followed in order by AMV and WCMV. Another consideration in choosing viruses is the region for which the final virus-resistant variety should be adapted. In the Southeast, white clover is widely used by North Carolina farmers. The major virus in North Carolina pastures was AMV and North Carolina also had more AMV in white clover than other southern states (1) . A white clover variety developed for the South- east should have resistance to AMV if it is to be accepted in North Carolina. The final consideration to be discussed in choosing viruses is what effect the viruses have on the species concerned. Very little research has been done comparing the effects of different viruses on clover yield. We noted that double infections of PSV and CYW were associated more with ladino clover plants with low forage ratings (Table 1) . However, more of the plants were infected with PSV than with CYVV. Therefore, we chose to screen for resistance to PSV, CYW, and AMV. Ini- tial concentration on PSV was proposed because of its widespread occurrence. VIRUS TECHNIQUES FOR SCREENING PROGRAMS Identifying virus resistance in a species such as white clover necessi- tates the use of methods that permit the screening of many plants. The screen- ing involves two main steps, 1) inoculating plants with the virus in a way to avoid escapes or to minimize escapes and 2) assaying or identifying infected plants including those that do not develop symptoms. Inoculation Techniques The inoculation procedures will be discussed in detail in the next paper. Briefly, each clover plant is mechanically inoculated four times, the uninfected plants are inoculated by two species of aphid vectors, and then the surviving plants are exposed to natural infection under field conditions. White clover presents a special problem where mechanical inoculation is concerned because all of the susceptible plants are not infected by a single inoculation. We decided to inoculate four times in order to infect as many susceptible plants as possible. As shown in Table 2 accessions with high sus- ceptibility were almost all infected by this inoculation procedure, while very few plants were infected in other accessions. After field exposure there is a 68 trend for relatively more uninfected plants from the accessions with more plants surviving mechanical inoculation than from the accessions with few plants surviving mechanical inoculation. Greenhouse aphid inoculations involve a great deal of work but they approach field conditions more closely. Two sources of techniques for handling aphids and using them as vectors are Aphid Technology by H. F. van Emden (16) and Transmission of Plant Viruses by Aphids by M. A. Watson (17) . In our pro- gram Myzus persicae (Sulz.) and Aphis craccivora (Koch.) colonies are main- tained in cages on Tendergreen mustard spinach (Brassica perviridia Bailey) , and Chenopodium quinoa Willd., respectively. The cages are illuminated with fluorescent and incandescent lights for a 19-hour photoperiod. Large numbers of aphids are brushed into plastic tubes and starved for 1 or 2 hours. Then about 100 aphids are placed on the top of an excised infected leaf for 3 or 4 minutes. Only the aphids which crawl to the under surface of the leaf and probe are used. About 10 aphids of each species are then placed on each plant to be inoculated. After several hours the plants are sprayed with malathion to kill the aphids. Field exposure is the last step in the inoculation procedure. We find that field exposure places the greatest inoculation pressure on white clover. There are several reasons for not using field exposure alone in the screening process although it can be effective if used in conjunction with proper assay procedures. Intensive greenhouse screening by mechanical and aphid inocula- tions allows for initial screening with individual, known viruses. This makes assay easier because a single plant species can be used for detection since no identification is necessary, yet resistance to each virus can be determined in each plant. Greenhouse screening also allows large numbers of seedlings to be screened and keeps the number of plants in the field small. The relative effectiveness of the three inoculation procedures is given in Table 3. The 104 plants used represent two vegetative cuttings from each of 52 clones inoculated by each method. In this way the inoculation techniques were compared on the same genotypes. The number of plants infected when the inocu- lation procedures are used sequentially will be discussed in the next paper. Assay Techniques Assay of plants inoculated with single viruses in the greenhouse requires only detection and not identification. Detection of virus infection only by the symptoms which develop on white clover misses many infected plants. When cowpea was used to detect PSV infection, mechanical inoculation of plants from 31 accessions resulted in 545 infected plants. Only 234 (43%) of these infected white clover plants had virus symptoms. Cowpea (Vigna unguiculata (L.) Walp. subsp. unguiculata) is a good assay plant for PSV. Three to four plants can be grown in 2-3 inch pots for inoculation in about 10 days. Symp- toms develop locally on the inoculated primary leaf in about 4 to 5 days but the final reading of symptoms should await distinctive systemic chlorotic vein banding as the trifoliate leaves unfold. Chenopodium amaranticolor Coste & Reyn, develops necrotic local lesions sometimes followed by systemic chlorotic vein banding when inoculated with CYW. Bountiful bean (Phaseolus vulgaris L.) develops necrotic local lesions when inoculated with AMV. When PSV and CYW both infect white clover, such as occurs in field inoculations, we use both cowpea and CL amaranticolor . Cowpea is not susceptible to most strains of CYW. On amaranticolor the necrotic local lesions caused by CYW stand out 69 I against the chlorotic local lesions of PSV; no systemic infection of CL amaranticolor occurs as a result of PSV infection. As mentioned earlier initial identification of the viruses found under different field conditions should be done with techniques to supplement the host range and reactions. The above assay procedures work under South Carolina conditions but variations may occur under other environmental conditions. VIRUS STRAINS AS THEY AFFECT RESISTANCE SCREENING Viruses mutate like other living material. Different viruses vary widely in their apparent mutation rate (12). As a result, many strains of some viruses, such as tobacco mosaic virus, have been characterized, but few strains of some other viruses, such as tomato bushy stunt virus, have been found. Plants resistant to one strain of a virus may not be resistant to other strains. Diachun's work with bean yellow mosaic virus (BYMV) resistance in red clover typifies this problem (3). Four strains of BYMV produced almost every combination of mosaic, necrosis or no symptoms on 55 red clover clones. Thus some clones exhibited only mosaic symptoms when inoculated with any of the four : strains, other clones exhibited no symptoms with any of the strains, and other clones exhibited different reactions to the different strains. The predominant strain of BYMV in Kentucky red clover remained the same over the last several years (4, 7), but this is not true for all viruses. For example, the predomi- nant barley yellow dwarf virus strain can change over a period of several years in a locality, and in different localities in the same year the predominant strains can be different (15) . Little work on strain separation has been done with AMV, CYVV, and PSV from clovers. J. P. Meiners (personal communication) has found different reactions of bean varieties to several isolates of PSV. L. T. Lucas (personal communication) found an isolate of CYW that produced systemic symptoms in cowpea. The problem of virus strains in the forage legumes still needs to be studied. That strains of the major forage viruses occur is beyond question, but their effect on a breeding program is unanswered except in the case of BYMV on red clover in central Kentucky. NATURE OF VIRUS RESISTANCE Very little research has been done on the nature of virus resistance in the clovers. Several types of resistance that have been found are discussed below. Resistance to BYMV in red clover is exhibited as a localized, hypersensi- tive reaction (4). A single source of resistance to CYVV in white clover has been studied. This plant 1) was susceptible to CYW only by repeated mechanical inoculation, 2) had a very low virus concentration when infected, and 3) had field resis- tance. This apparently is a multigenic type of resistance or tolerance. A single source of resistance in white clover to PSV has also been studied. The resistant plant has not been infected yet. When this plant was crossed with a susceptible plant the progeny were mostly resistant to PSV (24 resistant of 38 plants) . The S]^ selfed generation segregated into several resistance classes as shown in Table 4. These preliminary data suggest the presence of a dominant and a recessive gene controlling the resistance. From this discussion it is apparent that various types of virus resistance exist in clovers. This obviously complicates the production of varieties with resistance to several viruses. 70 CONTROL OF VIRUS DISEASES Several methods of controlling virus diseases have been devised. Most of these are more appropriate for other types of crops than forage legume, how- ever . Removal of sources of infection can be of some help with new plantings of forage legumes. Following this practice, new plantings would be started away from other pastures. Usually, however, the forage legumes serve as sources of viruses for other crops. Virus-free seed or vegetative stocks would appear to be of minor impor- tance also. However, certain viruses are seed transmitted in red clover, although in low percentages (6) . Virus-free vegetative stocks have also proved useful in breeder seed production where vegetatively propagated clones are required (2) . Modified planting and harvesting procedures can be used with some crops. Some annual crops can be planted after major aphid flights to escape infection, or they can be planted early and harvested before the virus infection reduces yield. These procedures probably cannot be adapted for forage crops. The use of reflective surfaces and oil sprays are new methods for control- ling virus diseases. For the reflective surface procedure to be effective, about 50% of t tie ground surface needs to be covered. This would not be possi- ble with forage crops. Oil sprays have been used to prevent virus spread, but are usually only effective in delaying infection. They would be too expensive for forage crops and would only delay infection several months if used. Control of vectors by chemical sprays has been used effectively with some viruses but not with the nonpersistent , aphid-transmitted viruses such as AMV, CYW, and PSV. For control of virus diseases of forage legumes, the best or perhaps the only control is breeding immune, resistant, or tolerant varieties either to the virus or against the vector. Some projects, such as those at Kentucky and North Carolina, have already shown that it is possible to incorporate resis- tance to virus diseases into forage legumes. The next report also indicates that selection of virus-resistant clones is possible. Perhaps someday we will have virus-resistant varieties. REFERENCES 1. Barnett, 0. W. , and P. B. Gibson. 1975. Identification and prevalence of white clover viruses and the resistance of Trifolium species to these viruses. Crop Sci. 15:32-37. 2. Barnett, 0. W. , P. B. Gibson, and A. Seo. 1975. A comparison of heat treatment, cold treatment, and meristem tip-culture for obtaining virus-free plants of Trifolium repens. Plant Dis. Reptr. 59:834-837. 3. Diachun, S., and L. Henson. 1960. Clones of red clover resistant to four isolates of bean yellow mosaic virus. Phytopathology 50:323-324. 4. Diachun, S., and L. Henson. 1974. Red clover clones with hypersensitive reaction to an isolate of bean yellow mosaic virus. Phytopathology 64:161-162. 5. Elliott, J. A. 1921. A mosaic of sweet and red clovers. Phytopathology 11:146-148. 6. Hampton, R. 0., and E. W. Hanson. 1968. Seed transmission of viruses in red clover: evidence and methodology of detection. Phytopathology 58:914-920. 71 7. Jones, R. T., and S. Diachun, 1976. Identification and prevalence of viruses in red clover in central Kentucky. Plant Dis. Reptr. 60:690- 694. 8. Kreitlow, K. W., and 0. J. Hunt. 1958. Effect of alfalfa mosaic and bean yellow mosaic viruses on flowering and seed production of Ladino white clover. Phytopathology 48:320-321. 9. Kreitlow, K. W. , 0. J. Hunt, and H. L. Wilkins. 1957. The effect of virus infection on yield and chemical composition of Ladino clover. Phytopathology 47:390-394. 10. Kreitlow, K. W. , and W. C. Price. 1949. A new virus disease of ladino clover. Phytopathology 39:517-528. 11. Lucas, L. T. , and C. R. Harper. 1972. Mechanically transmissible viruses from ladino clover in North Carolina. Plant Dis. Reptr. 56:774-776. 12. Matthews, R. E. F. 1970. Plant Virology. Academic Press, New York. 778 p. 13. Paliwal, Y. C. 1974. Some properties and thrip transmission of tomato spotted wilt virus in Canada. Can. J. Bot . 52:1177-1182. 14. Pierce, W. H. 1935. Identification of certain viruses affecting legumi- j nous plants. J. Agric. Res. 51:1017-1039. 15. Rochow, W. F. , and H. Jedlinski. 1970. Variants of barley yellow dwarf virus collected in New York and Illinois. Phytopathology 60:1030- 1035. 16. van Emden, H. F. 1972. Aphid Technology. Academic Press, New York. 344 p . 17. Watson, M. A. 1972. Transmission of plant viruses by aphids, p. 131-167. In C. I. Kado and H. 0. Agrawal (ed.) Principles and Techniques in Plant Virology. VanNostrand-Reinhold Company, New York. 18. Zaumeyer, W. J., and B. L. Wade. 1935. The relationship of certain legume mosaics to bean. J. Agric. Res. 51:715-749. TABLE 1. — Relation of forage ratings to virus infection in ladino clover Forage rating3 No. virus-infected plants^ PSV CYVV Both Total 0-5 22 13 12 23 6-10 9 6 6 9 Total 31 19 18 32 a Forage rating is from 0, plant dead, to 10, best forage rating. Some factors considered in the forage rating of 32 individual spaced plants included vigor, ground cover, and forage density. PSV = peanut stunt virus, CYVV = clover yellow vein virus. Both = plants infected with both PSV and CYW. 72 TABLE 2. — Effectiveness of mechanical inoculation of white clover accessions with peanut stunt virus Accession No. plants inoculated Plants not infected (%) 2682 56 2 3756 60 10 4249 50 14 4753 50 12 FC 40874 155 69 PI 4-2080-3 50 76 PI 234678 64 89 4804 54 62 TABLE 3 .--Comparison of white clover of mechanical, aphid, and field inoculation genotypes with clover yellow vein virus Inoculation method No. genotypes inoculated Mechanical Aphid (%)a (%) Field (%) 52 46 54 85 aPercent plants of the 52 genotypes infected of two vegetative propagules for each inoculation method. of each TABLE 4. — Incidence families from of peanut F^ crosses stunt of a virus (PSV) PSV resistant resistant plants in x PSV susceptible Resistance No. No . plants resistant/ class (%) families No. plants inoculated 98-100 4 173/175 91-93 2 81/88 81-88 3 115/135 46-51 2 46/95 73 IDENTIFYING VIRUS RESISTANCE IN WHITE CLOVER BY APPLYING STRONG SELECTION PRESSURE. II. SCREENING PROGRAM By P. B. Gibson and 0. W. Barnett Obviously, time does not permit a detailed discussion of all the logical subtopics of my assignment. I will barely mention some topics and will discuss others in more detail. The rationale for this approach is that a detailed dis- cussion would involve considerable information that has been presented elsewhere and is common knowledge to forage breeders. This discussion is more or less limited to white clover; however, with modification it applies to other species. JUSTIFICATION FOR SCREENING PROGRAM We believe the virus diseases collectively comprise the most important problem in white clover production. This belief is based on observations, cir- cumstantial evidence, and data. Unfortunately, definitive field data as would be supplied by paired plots of virus-free vs. virus-infected are not available. The plots can be estab- lished but to date no one has satisfactorily maintained virus-free plots. Positive air flow open end chambers (2), as have been used in air pollution research, may be a way to obtain a statistically valid measurement of the impor- tance of the viruses. I will briefly mention some of our reasons for consider- ing viruses the number one problem: a) Virus symptoms are common on clover in pastures. b) Results of surveys of pastures indicate a high incidence of virus diseases on clover (1&4) . c) Longevity of clover in renovated pastures generally is shorter than that of new stands. Usually a few clover plants persist and may serve as a source of the virus to infect new seedlings. d) Experimental data reported by Kreitlow (3) and later by Barnett and Gibson demonstrate the reduction in yields attributed to viruses under the conditions of the experiments. e) In space planted nurseries, we have observed a close association between infection with peanut stunt virus and decline of white clover plants . f) Comparisons of virus-free and virus-infected plants growing in pots in the greenhouse and in growth chambers have demonstrated the detrimental effects of the viruses. This evidence has convinced us of the importance of viruses. Consequently, we are devoting almost our entire effort to identifying virus resistance. PERTINENT CHARACTERISTICS OF WHITE CLOVER In general, the characteristics of white clover facilitate a screening and 74 breeding program. The following fragmentary statements apply to white clover plants or to the species: a) Easily propagated vegetatively and easily transplanted. b) Normally cross-pollinated. c) Most plants will produce selfed seed, especially at temperatures of about 35°C. d) Hand-pollinations are not difficult to make. e) Meeting the greenhouse requirements for growing, bringing into flower and seed production is relatively easy. f) Is an evolutionary tetraploid, but most inheritance is disomic. g) Is a perennial, will behave as an annual, and has been hybridized with other perennial and annual Trifolium species. h) Most plants will flower over a relatively long period and flowering is largely controlled by the photoperiod. i) Seed in dry-cold storage will remain viable for several years. THE SCREENING PROGRAM As an introduction to our discussion of the screening program I emphasize that it is a cooperative Federal-State program. A brief summary of the entire screening process is presented as a preview to help visualize the logic for the individual steps. Seedling plants are screened in the greenhouse first for resistance to Peanut Stunt Virus (PSV) . Susceptible plants are discarded and each surviving plant is vegetatively propagated to provide one plant to screen for resistance to Clover Yellow Vein Virus (CYW) , one plant to screen for resistance to Alfalfa Mosaic Virus (AMV) , and one plant to be transplanted into the field where it is exposed to the natural array of vectors and viruses. Preparing Plants for Screening Seed are planted in methyl bromide-fumigated soil, inoculated with rhizobia bacteria by watering with a slurry suspension of peat containing the bacteria or inoculated at time of transplanting by dipping roots in the slurry. The resulting seedlings are grown to about the second trifoliate leaf stage. About 50 to 100 seedlings of each source are transplanted individually into 4-inch pots. The intention is to screen 50 seedlings of narrow genetic base sources and 100 seedlings of broad genetic base sources such as mass- selected varieties. Screening for Resistance to PSV in Greenhouse Screening for Resistance to PSV by Mechanical Inoculations. When seed- lings attain the 5 to 10 leaf stage (about 4 to 6 weeks) they are mechanically inoculated (abrasive smear technique) with PSV. The inoculation is repeated weekly or at shorter intervals, for a total of four inoculations. Two weeks after the fourth inoculation, all plants with visual symptoms are discarded. On the remaining plants, stolons that extend over the rim of pots are pruned and the leaves are trimmed at a height of about one inch. One week later, the plants are assayed onto Vigna unguiculata (L.) Walp. cv. Blackeye cowpea seed- lings using young clover leaves as the source of inoculum. The initial reading of the assay cowpea plants is made 7 days after inoculation and the final 75 reading is made on the tenth day. All infected clover plants, as indicated by the responses on the cowpea seedlings, are discarded. The remaining clover plants are considered to be resistant to PSV by mechanical inoculation and are again pruned in preparation for inoculation by vector aphids. Screening for Resistance to PSV by Viruliferous Aphids (5&6) . One week after pruning, the plants are moved to an isolated section of the greenhouse and 10 viruliferous (PSV) Myzus persicae are placed on each plant. About one hour later, 10 viruliferous (PSV) Aphis craccivora are placed on each plant. After the plants have been exposed to the latter species of aphids for 1 hour or longer, the plants are treated with an appropriate pesticide to eliminate the aphids and are returned to the growing area of the greenhouse. Two weeks after exposure to aphids, the plants are pruned and 1 week later new growth is used as the source of inoculum to assay onto cowpea seedlings as was done after the mechanical inoculations. Again, all infected clover plants are discarded. Vegetative Propagation Each surviving plant is propagated vegetatively to provide one plant of each genotype to screen for resistance to CYVV, one to screen for resistance to AMV, one to transplant into the field, and one to hold in the greenhouse. Screening for Resistance to CYW Clover plants are screened for resistance to CYVV by the same procedure used to screen for PSV resistance, with the exception that plants of Cheno- podium amaranticolor Coste & Reyn, are used in lieu of cowpeas to assay for infected plants. Screening for Resistance to AMV Clover plants are screened for resistance to AMV by the same procedure used to screen for PSV resistance, with the exception that plants of Phaseolus vulgaris L. cv. Bountiful are used in lieu of cowpeas to assay for infected plants . Field Screening Rooted cuttings of the plants surviving the greenhouse screening for resis- tance to PSV are transplanted into a field. Past experience indicates that the requirements to effect a high incidence of infection with PSV and CYVV are present in this field. AMV infection occurs but at a lower incidence. Clover plants that survive the greenhouse screening and remain virus-free for 1 year or longer in this field are considered to possess some degree of resistance. Additional Comments The program is designed to identify resistance as much as possible while the plants are young and growing in small containers. Although we are seeking multiple resistance, i.e., resistance to PSV, CYW, and AMV, the program iden- tifies resistance to individual viruses. The program will be modified as experience dictates. Preliminary results indicate that resistance to mechanical inoculation, variation in vector 76 preference, virus strains, levels of tolerance in clover, variation in symptom expression, variation in susceptibility with age, and environmental effects all must be considered. We are exposing the plants to the viruses by using more than one method of inoculation in an effort to eliminate the chance of selecting for resistance to a virus by a specific method of inoculation and not resistance to the virus. At the present time, clover plants considered undesirable because of size, type of growth or other agronomic reasons are discarded. Preliminary results indicate that the greenhouse screening, after discarding virus-infected plants and agronomically undesirable plants, will supply all the plants we can clas- sify in the field. Elite Clones Plants surviving the above eliminations are considered elite genotypes and will be evaluated further to confirm their value. Advanced evaluations will include test crosses and progeny evaluations to insure that the resistance is transmitted and to determine the inheritance of the resistance. PRIORITY OF SOURCE MATERIALS FOR SCREENING We have given top priority to sources such as adapted varieties. A plant selected from such material can be used as is, to be a parent of an improved variety. Sources that require crossing and selecting to transfer resistance to a desirable agronomic line have a lower priority. In general, the materials we are screening and the priorities we have given the materials are: 1st Priority - Progenies from elite clones. 2nd Priority - Adapted varieties. 3rd Priority - Plant Introductions reported to be promising on the basis of preliminary tests. 4th Priority - Any white clover germplasm not included in above priorities. 5th Priority - Species hybrids. The species hybrid of TL ambiguum Bieb. and T_. repens L. probably offers the best resistance available. We placed it last because 1) the hybrid has to be made and 2) crossing and selecting to combine resistance, desirable agro- nomic characters, and stability may require considerable time. PROGRESS Approximately 4,000 seedlings have been fed into the program. New seed- lings are constantly started and plants are in all steps of the program. The percentage of plants that survive the inoculations varies from source-to-source . We interpret this variation to be an indication that levels of resistance exist within the species. A few plants from the early days of the program survived and were exposed in the field during the summer of 1976. Some of these plants remained virus- free and open-pollinated seed were harvested. Preliminary data from seedlings grown from the seed indicate that we are making progress. Since we have completed the screening program on relatively few sources, my examples will largely be limited to results from mechanical inoculations. The percentage of survivors may seem to be high but remember that inoculations with aphids and field exposure also eliminate plants. Our best estimate at present is that, on the average, about six plants out of 100 fed into the 77 TABLE 1. — Virus-free white clover plants at successive steps in the screening program Category No. plants % Total plants from 17 accessions 1036 100 Plants not infected with PSV after: Mechanical inoculations 431 42 Aphid inoculations 314 30 Field exposure (one season) 94 9 Plants free of PSV, CYVV and AMV after one season in field 63 6 TABLE 2. — Percent of white clover plants free of PSV after four mechanical inoculations. Source % PSV free Varieties : California Ladino 76 Green Acres 17 Louisiana S-l 46 Merit 30 Pilgrim 31 Tillman 46 Germplasm lines: PI 388632 16 PI 234678-a 74 PI 239976 83 PI 234678-b 89 FC 40874 69 O.P. Progenies from clones: 2682 2 4249 14 4736 54 4758 30 4804 34 O.P. Progenies from selected clones (2nd cycle): 1-40 (PSV infected in field) 35 4-44 (PSV infected in field) 29 1-93 (PSV free in field) 97 3-36 (PSV free in field) 90 78 program will reach the field and survive virus-free through the first growing season. In the case of some sources, no plants survived. Selected examples of results from our screening program are presented in Tables 1 and 2. These are representative samples, but obviously, comparisons are not statistically valid since screening of the various sources was not ran- domized, replicated and conducted simultaneously. REFERENCES 1. Barnett, 0. W. and P. B. Gibson. 1975. Identification and prevalence of white clover viruses and the resistance of Trifolium species to these viruses. Crop Sci. 15:32-37. 2. Heagle, Allen S., Denis E. Body, and Walter W. Heck. 1973. An open-top field chamber to assess the impact of air pollution on plants. J. Environ. Qual. 2:365-368. 3. Kreitlow, K. W. , and 0. J. Hung. 1958. Effect of alfalfa mosaic and bean yellow mosaic viruses on flowering and seed production of ladino white clover. Phytopathology 48:320-321. 4. Lucas, L. T. and C. R. Harper. 1972. Mechanically transmissible viruses from ladino clover in North Carolina. Plant Dis. Reptr. 56:774-776. 5. vanEmden, H. F. 1972. Aphid Technology. Academic Press, New York. 344 p. 6. Watson, M. A. 1972. Transmission of plant viruses by aphids, p. 131-167. In C. I. Kado and H. 0. Agrawal (ed.) Principles and Techniques in Plant Virology. VanNostrand Reinhold Company, New York. 79 THE APPLICATION OF THE COEFFICIENT OF INBREEDING TO FORAGE BREEDING METHODS By Thad H. Busbice Inbreeding is the mating of relatives. The more related the parents, the more inbred will be the offspring. In plants the most extreme form of inbreeding is selfing, followed by backcrossing of offspring to parent and sib mating. These forms of inbreeding are easy to recognize, but it is also important to recognize that some inbreeding occurs even when the parents are only xemotely related. Inbreeding can be defined by two genetic parameters: (1) The coefficient of parentage-- the probability that a random gene at a locus from one parent is identical to a random gene from that locus in the other parent. (2) The coefficient of inbreeding--the probability that two genes picked at random from a locus are identical by descent. It follows that the coefficient of inbreeding is computed from a knowledge of the coefficient of parentage. Wright (1921), Malecot (1948) and Kempthorne (1957) have contributed to this concept. To have meaning, the coefficient of inbreeding must relate to some con- ceptual noninbred population. It is not necessary that this noninbred population be random-mated or to be in equilibrium. It is necessary only that it is conceptually defined, and that comparisons of inbreeding co- efficients be confined to that conceptual framework. Only individuals are inbred, but a family of such individuals is said to be an inbred family. Also, any population that contains inbred individuals is considered to be an inbred or partly inbred population. The coefficient of inbreeding of a popu- lation is the average of the coefficients of inbreeding of the individuals that make up the population. Thus, a forage variety is said to be partly in- bred when any of its plants are inbred or partly inbred. Most inbreeding computations can be resolved from the coefficients of parentage of four mating designs: SELFING r = -yr- [1 + (2k -1) F ] = the coefficient of parentage of individual x XX X x with itself. 80 RACKCROSSING r , s = — — !- 2k 1 jr + 1— r = the coefficient of parentage of parent x x(xy) 4k 4k x 2 xy with its offspring xy (from the mating of parent x with parent y) . FULL SIB-MATING r. w . = ft* [2 + (2k-l) (F + F ) + 4kr ] = the coefficient of parentage (xy) (xy) 8k x y xy of individual xy (from the mating of parents x and y) with its full sib. HALF SIB-MATING r. w . = ~~ [1 + (2k-l) F +2k(r + r + r )]= coefficient of (xy) (yz) 8k y xy xz yz parentage of individual xy (from the mating of parents x and y) with its half-sib yz (from the matings of parents y and z). Where: F^ and F^ are the coefficients of inbreeding of parents x and y; r , r , and r are the coefficients of parentage of parents x, y , and z : xy xz yz and k is one-half the ploidy number (i.e., 1 for diploids, 2 for autotetra- ploids, etc.). The coefficient of inbreeding of any individual ij from mating parents i and j is 1 Fij 2k- 1 [k r. . + (F. + F.)] 2 i J It is necessary to define the degree of inbreeding and relationship in the parents from which the degree of inbreeding can be computed in the offspring. The degree of inbreeding in a random mating population, such as synthe- tic varieties, can be computed easily from existing formulae. (See Busbice, 1969). Because many forage varieties are propagated as synthetic varieties, certain relationships about synthetic varieties are important to know; /in 1 rl + (2k-l)F i rn~li r r . . j- (1) r = — [ F- — oj + L J r = the average coefficient of parentage 1 n 2k n o among individuals in advanced generations. Where: n = the number of parents r = the average coefficient of parentage among the parents. F^ = the average coefficient of inbreeding of the parents. 81 When the parents are noninbred and unrelated r^ = i1 (2) F = r^ + [s (1-r^)] / [s + 2k (1-s)] = the coefficient of inbreeding jl at equilibrium. Where: s = the When s equals zero, k s (3) D - 2k- 1 frequency of selfing the distance traveled toward equilibrium with each generation of random mating following the first genera- tion. When the population is diploid and no selfing occurs, equilibrium is reached in one generation past the Syn 1, that is, in the Syn 2. In polyploids, equilibrium is reached asymptotically, but nevertheless rapidly, with genera- tions of random mating. In autotetraploid varieties multiplied without self- ing 2/3 the distance to equilibrium is covered with each generation. Selfing increases inbreeding and slows the approach to equilibrium. Why be concerned about the coefficient of inbreeding? All naturally outcrossing forage species (alfalfa, crownvetch, clover, orchardgrass , and many others) are subject to severe inbreeding depression of forage and seed yield, and some depression may occur even when the degree of inbreeding is small. TREADMILL EFFECT OF RECURRENT SELECTION Recurrent selection is a mild form of inbreeding in that each cycle is started from a finite population. The fewer parents used to initiate each cycle, the greater will be the risk of serious inbreeding, and in- breeding will increase with each generation of selection. A population created by recurrent selection may have great plant to plant variation, yet fail to respond to continued selection pressure. Although exceptional parents are selected, the progeny may not exceed the previous cycle in performance. The reason is that a threshold level of in- breeding has been reached that offsets any advantage possible from selection. The answer is in the coefficient of inbreeding: F. . 1J krr + r1 + v1 While the parents may be related (r. . / 0) and the ij * Therefore, one cannot be exceptional and possib]y noninbred, they can be resulting progeny partly inbred (F^ ^ 0) . assured of continued success from recurrent 82 selection just because a great amount of genotypic variation remains in a population. GENOTYPIC VARIATION An intermating population contains a mixture of mating designs, i.e., full and half sib-matings and possibly selfing, outcrossing, and the mating of cousins. Therefore, all individuals issuing from an intermating popula- tion will not have the same degree of inbreeding or show the same level of inbreeding depression. Thus, the genotypic variance of an intermating popula- tion, such as those used in recurrent selection programs, may be exaggerated by inbreeding. On the other hand, deliberate inbreeding will sometimes produce sur- prising uniformity in the progeny. For example, selfing a noninbred plant will produce an S, family, each member of the family being full sibs of the other members, ana each having the same degree of inbreeding. In addition, in autopolyploids restricted segregation occurs because of the polyploid gamete. While one might normally expect wide segregation in an family, variation for some characters may be less than such variation in intermating populations . RESIDUAL INBREEDING In autopolyploids, such as alfalfa, an individual will be inbred to a degree if its parents were inbred. This is obvious from the inbreeding formula : F ~ ij 2k- 1 [k r. . + ^ (F. + F.) ] ij 2 i j Even though the parents are totally unrelated (r^ j = 0) , a residual of in- breeding will be passed from the parents to the offspring through the gametes. In autotetraploids the offspring will contain 1/3 of the average inbreeding of the parents. DELAYED INBREEDING OR TIME BOMB EFFECT Synthetic varieties produced without selfing from diploid parents will stabilize in the Syn 2 generation. However, in autopolyploids equilibrium is reached asymptotically and a snythetic variety will not stabilize until the fourth or more advanced generations. Synthetic varieties produced from noninbred parents will become increasingly more inbred with each generation until equilibrium is reached, the amount of inbreeding being inversely related to the number of parents used to start the variety. Thus, a variety that performs exceptionally well when tested in the Syn 1 and Syn 2 generations may perform disappointingly in advanced generations when it reaches the farmer because of inbreeding depression. Such depression will likely surface first in reduced seed production. 83 PREDICTING YIELD In heterotic species, such as most forage species, there is a systematic relationship between the coefficient of inbreeding and yield. This relation- ship may be linear or exponential, but once it has been determined, the relationship can be used to predict the performance of partly inbred popula- tions. One such relationship (presented by Busbice and Gurgis, 1976) is: Ye ' h - t<2k-D(Y1 - Slavg_)/kn] Where Y = the equilibrium yield of a synthetic variety e Y^ = the Syn 1 yield, or the average of the single crosses among the parents. ^lavg = t'^ie avera8e self yields of the parents. Again k is one-half the ploidy, and n is the number of parents. References Busbice, T. H. 1969. Inbreeding in synthetic varieties. Crop Science 9:601-604. Busbice, T. H. and R. Y. Gurgis. 1976. Evaluating parents and predicting performance of synthetic alfalfa varieties. ARS-S-130, Agricultural Research Service, U. S. Dept, of Agriculture. Kempthorne, D. 1957. An introduction to genetic statistics. John Wiley and Sons, Inc. New York. p. 72-100. Malecot, G. 1948. Les Mathematiques of l'heredite. Masson et Cie, Paris . Wright, S. 1921. Systems of mating 1-V. Genetics 6:111-178. 84 CHARACTERIZATION OF FORAGE TISSUE BY TRANSMISSION AND SCANNING ELECTRON MICROSCOPY by Danny E. Akin, E. L. Robinson, and Donald Burdick We have used both transmission and scanning electron microscopy (TEM and SEM, respectively) to confirm and expand observations of forages by light microscopy, but the most important use has been to study the relative rates and extents of rumen microbial digestion of different forage tissues in their structurally intact state. In order to fully understand these investigations, one should realize the basic advantage of each type of microscope. Table 1 shows a comparison of the magnification and resolution of the light, trans- mission electron, and scanning electron microscopes. Transmission electron microscopy provides the greatest resolution while a large depth of field is available with scanning electron microscopy. TISSUE CHARACTERIZATION Patterns of tissue organization, relative cell wall thickness, and cell wall rigidity are easily seen by SEM and can complement light and histochemical observations (Akin and Burdick, 1973). A cross-section of a Coastal bermuda- grass (CBG) leaf blade observed by SEM is shown in Figure 1. CBG blades had closely spaced vascular bundles surrounded by wel 1 -developed parenchyma bundle sheaths which is typical for warm-season grasses (Brown, 1958; Downton and Tregunna, 1968). CBG had a high percentage of vascular bundles in leaf blades (Akin and Burdick, 1975). The more loosely arranged and thin-walled mesophyll cells, which comprised a lower percent of blade area than in cool -season species (Akin and Burdick, 1975), occupied the area between bundles. The epidermal cells were thick-walled compared to Lhe mesophyll. Thickened, rigid walls of lignified cells (as determined histochemical ly) comprised the scleren- chyma and xylem area of the vascular bundles. TEM of a CBG blade (Fig. 2) revealed that the bundle sheath cell wall was laminated (i.e., alternate elec- tron dense and transparent layers) and slightly less than one ym wide. Addi- tionally, the bundle sheath cells contained chloroplasts with large numbers of starch grains, typical for C4 or warm-season grasses; thin-walled mesophyll cells usually lacked starch (Downton and Tregunna, 1968). SEM of Coastcross-1 bermudagrass (CX-1 ) leaf blades revealed tissues identical to those in CBG. Histochemical and morphometric studies have con- firmed these similarities (Akin and Burdick, 1973; Akin and Burdick, 1975). However, differences in the size of small vascular bundles and arrangement of the bundle sheaths around the large bundles existed in Pensacola bahiagrass (PBG) leaf blades (Fig. 3) as compared to CBG. Ky-31 tall fescue (Fig. 4), an anatomical representative of the cool- season, festucoid grasses (Brown, 1958), differ even more from CBG with vari- 85 TABLE 1 . --Comparisons of types of microscopes Type o Resolution (A) Magnification Light Microscope 2000 up to 1 ,000 to 1 ,200 x Transmission Electron <10 up to 200,000 x or > Microscope Scanning Electron 50 to 500 up to 200,000 x Microscope (Provides a Large Depth of Field Giving a Three-Dimensional Image) FIGURE 1.--SEM of cross-section of Coastal bermudagrass leaf blade. Vascular bundles are closely spaced and have well developed parenchyma bundle sheaths (P). Mesophyll (M) separates bundles, which are connected to the epidermis (E) by sclerenchyma (S). X629. 86 3 FIGURE 2.--TEM of Coastal bermudagrass leaf blade. Parenchyma bundle sheath cells (P) are closely adjoined and have thick, laminated cell walls; thin-walled mesophyll (M) cells are loosely-arranged. Starch grains (arrows) are numerous in chloroplasts of parenchyma sheath cells; chloroplasts in the mesophyll lack starch. X4,752. FIGURE 3.--SEM of cross-section of Pensacola bahiagrass leaf blade. Vascular bundles are closely spaced and have well developed parenchyma bundle sheaths (P). Mesophyll (M), epidermis (E), and sclerenchyma (S) are noted. X614. 87 FIGURE 4.--SEM of cross-section of Ky-31 tall fescue leaf blade. Vascular bundles are widely spaced and the parenchyma bundle sheath (P) is not wel 1 -developed. Mesophyll (M), epidermis (E), and sclerenchyma (S) are noted. X275. FIGURE 5.--SEM of Coastal bermudagrass blade incubated 12 hours with rumen bac- teria. Phloem and mesophyll are degraded, but parenchyma sheath and epidermis are only partially removed; lignified vascular and sclerenchyma cells are in- tact. X234. 88 ations in the thickness of the bundle sheath cell wall and in inherent rig- idity. Mesophyll tissue usually occupied more leaf blade area than in warm- season grasses (Akin and Burdick, 1975). CHARACTERIZATION OF TISSUES INCUBATED WITH RUMEN MICROORGANISMS Leaf Blades. SEM of grasses incubated with rumen microorganisms ( in vitro) revealed patterns of specific tissue digestion of intact, unground forages. Cell wall digestion, therefore, could be evaluated for the relative rate and extent of degradation by rumen microorganisms in relation to the structural features of the tissues. The depth of field of SEM permitted examination of tissue digestion from the cut ends of blade sections without serial sectioning and provided greater magnification and resolution vs. that obtained with light microscopy (Table 1). A comparison of leaf blade sections digested for 12 hours with aliquots of the same rumen fluid inoculum revealed differential tissue loss between forage cultivars (cf Fig. 5 with 6), forage species (cf Fig. 5 with 7 with 8), and forage types (cf Fig. 5, 6, 7 with 8). Although differences in the degradation of tissue types existed among forages, a pattern was found in all species examined: mesophyll and phloem were more easily digested than parenchyma sheath and epidermis while sclerenchyma and lignified vascular tissue (i.e., inner bundle sheath, xylem) were essentially indigestible. Identical patterns of tissue degradation have been shown for these and other forage grasses by light microscopy (Regal, 1960; Hanna, Monson, and Burton, 1973). TEM of rumen bacterial interrelationships with forage tissues (Akin, Burdick, and Michaels, 1974) indicated that bacterial attachment to slowly degraded cell walls often occurred (Fig. 9) whereas the rapidly digested tissues were often degraded apparently without bacterial attachment; lignified tissues had few attached bacteria (Fig. 10). Two factors appear to influence the ease (or relative rate) and extent of blade digestibility and perhaps should be considered in forage breeding pro- grams designed for increasing digestibility. These factors are: i) the amounts of tissue types present, and ii) the inherent cell wall nature of similar tissues among grasses. The first factor is demonstrated in Table 2. The less digestible warm-season grass blades usually had a higher percentage of the more slowly degraded epidermis and parenchyma bundle sheath; conversely, the more digestible cool -season blades consisted of a higher percentage of the easily digested mesophyll and phloem. It would therefore appear worthwhile to select for forages with a higher percentage of mesophyll and phloem to improve digestibility per se. This difference in the 'rate' of digestibility of digestible tissue has been recognized and used to expand equations mathemat- ically describing cell wall digestion (Mertens, 1977). However, the amount of (non-degraded) lignified tissue appeared to limit only the extent of tissue digestion (Akin and Burdick, 1975). The amount of these indigestible tissues were similar between warm-season and cool-season grasses and were lowest in some warm-season species. This limitation of only the extent of tissue diges- tion by lignin has been suggested by others (Smith, Goering, and Gordon, 1972; Mertens, 1977). Perhaps plant breeding could be useful to increase the rate of digestibility by modifying blade anatomy as has been found in species inter- mediate between C4 and C3 Panicum spp. (Brown and Brown, 1975) and with Fi hybrids of C4 and C3 parents in Atriplex (Bjorkman, 1976). Of course, poten- tial modifications must be considered in light of the effect on forage yield 89 FIGURE 6.--SEM of Coastcross-1 bermudagrass blade incubated 12 hours with rumen bacteria. Phloem, mesophyll, and much of the parenchyma sheaths and epidermis are degraded; lignified tissues are intact. X288. FIGURE 7.--SEM of Pensacola bahiagrass blade incubated 12 hours with rumen bac- teria. Phloem and mesophyll are degraded, but epidermis and parenchyma sheaths (of small bundles) are only partially removed; lignified tissues are intact. X288. 90 FIGURE 8.--SEM of Ky-31 tall fescue blade incubated for 12 hours with rumen bac- teria. Digestible tissues are removed leaving only lignified cells. X252. FIGURE 9.--TEM of Ky-31 tall fescue bundle sheath cell wall with attached, cellu- lolytic rumen bacteria. Several types of rumen bacteria (B) adhere closely to fhp Diant wall (W) during degradation. XI 3,050. 91 Table 2. --Percent of tissues in leaf blades characterized by ease of digestibility Grasses Rapidly Degraded (Phloem & Mesophyl 1 ) Slowly Degraded (Epidermis and parenchyma sheath) Nondegraded (Lignif ied vascular and sclerenchyma ) CBG 31.0 54.7 14.3 CX-1 27.2 56.2 16.6 PBG 54.7 36.4 8.9 Dal 1 is 45.9 45.0 9.1 Pangola 33.8 57.9 8.2 Crab 35.6 57.6 6.3 Brome 55.6 25.6 19.0 Orchard 56.0 29.4 15.7 Timothy 56.2 31.4 12.4 B1 uegrass 66.0 21.8 12.3 Ky-31 62.0 27.0 11.0 Kenhy 63.8 23.5 12.7 TABLE 3. --Percent degraded parenchyma bundle sheaths in warm-season and cool -season grasses after 12 hours incubation with rumen microorganisms Percent Parenchyma Bundle Sheath Grass Undegraded* Partially Degraded+ Degraded++ CBG 55.8 34.8 9.3 CX-1 25.0 70.8 4.2 PBG 0 13.3 86.7 Da 1 1 i s 100 0 0 Brome 0 0 100 Orchard 0 3.4 96.6 B1 uegrass 0 0 100 Timothy 0 12.5 87.5 Ky-31 14.3 42.9 42.9 Kenhy 0 63.6 36.3 * More than 3/4 of sheath cells undegraded. + At least 1 cell but no more than 3/4 sheath cells undegraded. ++ All sheath cells completely degraded from the depth of focus of the microscope. 92 which also appears to be related to the anatomy and physiology of warm-season plants (Downton and Tregunna, 1968; Black et al., 1971; Bjorkman, 1976). In regard to the second factor (i.e., inherent cell wall nature), SEM has shown variations in the ease of digestibility of anatomically similar tissues among various forages (Fig. 5 and 6; Akin, Burdick, and Amos, 1974). Table 3 shows variations in parenchyma bundle sheaths for blades of warm- and cool- season grasses. After 12 hours incubation with rumen microorganisms , the sheaths were mostly undegraded or only partially degraded in 3 of 4 warm-season forages. Conversely, in cool-season forages, more bundle sheath cells were partially or totally degraded. Additionally, comparisons using SEM of digested tissue in hybrids with higher digestibilities (i.e., CX-1 vs. CBG (Lowry et al . , 1968); Kenhy vs. Ky-31 tall fescue (Buckner, Bush, and Burrus, 1972)) indicated that cell walls had been modified making them more digestible al- though anatomically the leaf blades were identical (Akin and Burdick, 1975). Accordingly, there appears to exist chemical -physical differences in the cell walls not discernible with this methodology that affects the ease of digesti- bility. These specific factors are not as yet defined; however, their eluci- dation would appear to be of significant value to forage breeders. Table 4 shows differences in cell wall rigidity of parenchyma bundle sheaths stressed during preparation for SEM. Warm-season sheaths were 100% intact while many cool -season sheaths were partially collapsed. Extraction with acid detergent also revealed differential removal of similar tissues among forages and also indicated that inherent differences in cell walls may be related to digestibility (Akin, Barton, and Burdick, 1975). Warm-season grasses are known to store starch grains preferential ly in chloroplasts of parenchyma bundle sheath cells (Fig. 2) of leaf blades (Downton and Tregunna, 1968; Black and Mollenhauer, 1971). However, the fate of these highly nutritious starch grains in the digestion of structurally intact cells was not known. TEM of blades incubated with rumen microorganisms indicated that starch grains remained intact until cellulolytic bacteria degraded the cell wall, and then amylolytic bacteria hydrolyzed the starch grains (Fig. 10, 11). Starch per se is virtually 100% digestible (Dekker, Richards, Playne, 1972; Van Soest, 1967), and "starch, in common with soluble carbohydrates , exhibits a high percentage of conversion into fermentation products and cells" (Hungate, 1966). However, as shown earlier (Table 3) the ease of digestibility of parenchyma bundle sheaths and, therefore, apparently the ease of availabil- ity of nutrients contained therein, varies among forage types, species, and cultivars. This difference in availability of nutrients may be a factor asso- ciated with the relative nutritive value of forages. In regard to photosyn- thetic efficiency of warm-season (C4) grasses, Downton and Tregunna (1968) stated that "the breeding programs in which progeny are selected for lower rates of photorespiration, and the more efficient C4 pathway, offers attractive possibilities for increasing dry matter production". However, from Table 3 and Figures 10, 11, it would appear that breeding programs must be concerned, in addition to yields, with the digestibility of cell walls per se and, further- more, perhaps even the availability of nutrients within certain slowly digested cell s . 93 TABLE 4. --Percent structurally intact parenchyma bundle sheaths of warm-season and cool -season grasses after 72-hour incubation in control flasks Percent Parenchyma Bundle Sheath Grass Intact* Partially Intact+ Collapsed-H- CBG 100 0 0 CX-1 100 0 0 PBG 100 0 0 Dal 1 is 100 0 0 Brome 30.7 61.5 7.7 Orchard 0 50.0 50.0 B1 uegrass 40.0 60.0 0 Timothy 50.0 50.0 0 Ky-31 71.4 28.5 o Kenhy 57.8 42.1 o ! * More than + At least 1 ++ No sheath 3/4 of sheath cells structurally intact, cell but no more than 3/4 of sheath cells cells structurally intact. structurally intact. FIGURE 10.--TEM of Coastal bermudagrass blade degraded by rumen bacteria. Paren- chyma bundle sheath cell walls (W) are partially degraded and many rumen bac- teria adhere to the plant wall. Amylolytic bacteria have not yet hydrolyzed starch grains (arrows). The lignified, inner bundle sheath (I) is intact with few attached bacteria. X3,132. 94 From these data, the percentages of digestible tissue types and inherent cell wall differences (e.g., constituents, binding, or organization) appear to affect ease of digestion of leaf blades. Therefore, analysis for lignin or lignified tissue as a survey tool in breeding would provide information on the extent of blade digestibility, but not necessarily on the 'rate' of structur- ally intact blades. However, to fully understand plant digestion and the factors which affect it, one must examine all parts, i.e., blades, sheaths and stems, of grasses. Stems and Sheaths. Previous work had indicated that factors (in partic- ular lignin) in sheath and stems limit digestibility to a greater degree than those factors in leaves as plants mature (e.g., Pritchard, Folkins, and Pigden, 1963; Hanna, Monson, and Burton, 1976). To examine ul trastructural factors affecting digestibility with age of plant parts, we examined top, middle, and bottom portions of CBG blade, sheath, and stem grown for 5.5 months (green- house) to maximize factors limiting digestibility. We evaluated the portions for the histochemistry, chemistry, percent tissue type, IVDMD, and digesti- bility of the intact tissue (Akin, et al . , 1977). Our data agreed with that of Hanna et al. (1976) on bermudagrasses evaluated at 1 and 4 weeks in that stem (and, in our work, sheath) portions decreased in digestibility with age, where- as blades did not. Our work indicated that the decrease in sheath and stem digestibility appeared to be caused by an increase with age in chlorine-sulfite positive 1 ignif ication (not stainable with acid phlorogl ucinol ) in the paren- chyma cells. These cells, degraded in top portions, were not degraded in middle and bottom portions by rumen microbes after 72 hours (Fig. 12, 13). Furthermore, lignin percent increased over three percentage units and IVDMD decreased about 15 units with age (Akin et al., 1977). Recent investigations in our laboratory have indicated that, in 4 to 8 week old bermudagrass culti- vars, parenchyma cells in bottom stems were often less rapidly digested; in certain cultivars (i.e., common and Coastal), portions of the parenchyma re- mained after 72 hours of microbial digestion. Hanna et al. (1976) reported that amounts of "anatomical components resistant to digestion" in stems did not permit differentiation of high- and low-quality bermudagrass genotypes at the same age; their light micrographs indicated resistance to digestion in some parenchyma cells of 4-week-old CX-1. Schank, Klock, Moore (1973) reported that the area of vascular tissue in stems did not increase from 5 weeks to maturity in limpograss. Furthermore, Pigden (1953) reported progressive 1 ignification with age into the parenchyma cells of wheatgrass and bromegrass stems. From the available data, it would appear the breeders must evaluate factors in addition to vascular or thick-walled, fibrous tissue for limitations to stem digestibility. The extent of 1 ignification may progress into stem parenchyma cells and impede degradation. SUMMARY TEM and SEM have been useful in evaluating the structurally intact cells of forage tissue for both ease (or relative rate) and extent of degradation by rumen microorganisms in vitro. Amounts of tissue types as well as inherent cell wall differences of tissue appeared to affect the digestion of leaf blades of forages reported herein. Certain cultivars, resulting in higher digestibility over other cultivars within species, were shown to have more rapidly digestible cell walls of similar tissues. Lignification of cell walls 95 FIGURE 12.--SEM of top stem of Coastal bermudagrass incubated for 72 hours with rumen bacteria. Phloem, cortex, and parenchyma have been degraded leaving only the lignified epidermis (E), sclerenchyma ring (R), and vascular bundle (V). X374. FIGURE 11.--TEM of Pensacola bahiagrass blade degraded by rumen bacteria. Cellu- lolytic bacteria apparently have degraded the wall of the parenchyma cell, and amylolytic bacteria have entered the cell and hydrolyzed starch grains; the adjacent cell's wall is undegraded, no bacteria have entered, and starch grains are intact. X4,698. I 96 FIGURE wi th (V) 13.--SEM of bottom stem of Coastal bermudagrass incubated for rumen bacteria. Epidermis (E), sclerenchyma ring (R), vascul (except phloem), and parenchyma cells (C) are all undegraded. 72 hours ar bundles X374. 97 appeared to affect the extent of digestion in blades and certain tissues of stems. However, evaluation for the thick-walled sclerenchyma ring and xylem cells in stems may not in all forage species indicate limitations to the rate or extent of digestion with advanced maturity. These findings may be useful tel plant breeders in developing forage varieties of improved nutritive value. REFERENCES Akin, D. E., Barton, F. E., II, and Burdick, D. 1975. Scanning electron microscopy of Coastal bermuda and Kentucky-31 tall fescue extracted with neutral and acid detergents. J. Agric. Food Chem. 23:924-927. Akin, D. E., and Burdick, D. 1973. Microanatomical differences of warm- season grasses revealed by light and electron microscopy. Agron. J. 65: 533-537. Akin, D. E., and Burdick, D. 1975. Percentage of tissue types in tropical and temperate grass leaf blades and degradation of tissues by rumen micro- organisms. Crop Sci. 15:661-668. Akin, D. E., Burdick, D. , and Amos, H. E. 1974. Comparative degradation of Coastal bermudagrass , Coastcross-1 bermudagrass , and Pensacola bahiagrass by rumen microorganisms revealed by scanning electron microscopy. Crop Sci. 14:537-541. Akin, D. E. , Burdick, D. and Michaels, G. E. 1974. Rumen bacterial inter- rel ationshi ps with plant tissue during degradation revealed by trans- mission electron microscopy. Appl. Microbiol. 27:1149-1156. Akin, D. E., Robinson, E. L. , Barton, F, E., II, and Himmelsbach, D. S. 1977. Changes with maturity in anatomy, histochemistry, chemistry and tissue digestibility of bermudagrass plant parts. J. Agric. Food Chem. 25:179- 186. Bjorkman, 0. 1976. Adaptive and genetic aspects of C4 photosynthesis, p.287- 309. ]_n R. H. Burris and C. C. Black (ed. ) CO2 metabolism and plant producti vity , University Park Press, Baltimore, MD. Black, C. C., Edwards, G. E., Kanai, R. , and Mollenhauer, H. H. 1971. Photosynthetic assimilation of carbon in certain higher plants. Second Int. Congr. Photosyn. , 1745-1757. Black, C. C., Jr., and Mollenhauer, H. H. 1971. Structure and distribution of chloroplasts and other organelles in leaves of various rates of photo- synthesis. Plant Physiol. 47:15-23. Brown, R. H. , and Brown, W. V. 1975. Photosynthetic characteristics of Panicum miliodes, a species with reduced photorespiration. Crop Sci. 15:681-685. Brown, W. V. 1958. Leaf anatomy in grass systematics. Bot. Gaz. 119:170-178. 98 Buckner, R. C. , Bush, L. P. , and Burrus, P. B. , II. 1972. Kenhy - potentially a new tall fescue variety. Agronomy Research - 1972 Misc. 402:3-5. (Department of Agronomy, College of Agriculture, University of Kentucky, Lexington) . Dekker, R. F. H. , Richards, G. N., and Playne, M. J. 1972. Digestion of polysaccharide constituents of tropical pasture herbage in the bovine rumen. I. Townsville stylo (Stylosanthes humilis). Carbohyd. Res. 22:173-185. Downton, W. J. S., and Tregunna, E. B. 1968. Carbon dioxide compensation - its relation to photosynthetic carboxylation reactions, systemtics of the Gramineae, and leaf anatomy. Can. J. Bot. 46:207-215. Hanna, W. W. , Monson, W. G. , and Burton, G. W. 1973. Histological examination of fresh forage leaves after in vitro digestion. Crop Sci. 13:98-102. Hanna, W. W., Monson, W. G., and Burton, G. W. 1976. Histological and in vitro digestion study of 1- and 4-week stems and leaves from high and low quality bermudagrass genotypes. Agron. J. 68:219-222. Hungate, R. E. 1966. The rumen and its microbes. Academic Press, Inc., New York. Lowrey, R. S. , Burton, G. W., Johnson, J. C., Jr., Marchant, W. H., and McCormick, W. C. 1968. In vivo studies with Coastcross-1 and other bermudas. Ga. Agric. Exp. Sta. Res. Bull. 55:5-22. Mertens, D. R. 1977. Dietary fiber components: relationship to the rate and extent of ruminal digestion. Federation Proc. 36:187-192. Pigden, W. J. 1953. The relation of lignin, cellulose, protein, starch, and ether extract to the "curing" of range grasses. Can. J. Agric. Sci. 33:364-378. Pritchard, G. I., Folkins, L. P. , and Pigden, W. J. 1963. The in vitro digestibility of whole grasses and their parts at progressive stages of maturity. Can J. Plant Sci. 43:79-87. Regal, V. 1960. The evaluation of the quality of pasture grasses by the microscopic method. Proc. VIII Int. Grassld. Cong., 522-524. Schank, S. C., Klock, M. A., and Moore, J. E. 1973. Laboratory evaluation of quality in subtropical grasses. II. Genetic variation among Hemarthrias in in vitro diqestion and stem morphloqy. Aqron. J. 65:256- 258. Smith, L. W. , Goering, H. K. , and Gordon, C. H. 1972. Relationships of forage compositions with rates of cell wall digestion and indigestibility of cell walls. J. Dairy Sci. 55:1140-1147. Van Soest, P. J. 1967. Development of a comprehensive system of feed analyses and its application to forages. J. Anim. Sci. 26:119-128. oo TROPICAL GRASS BREEDING AND EARLY GENERATION TESTING WITH GRAZING ANIMALS By K. H. Quesenberry, Rex L. Smith, S. C. Schank, and W. R. Ocumpaugh Improvement of tropical and subtropical forage grasses by plant breeding may present some unique problems to the plant breeder. For instance, the range of adaptability of most tropical grasses has not been adequately determined. Plant breeders in the temperate areas may know that one or two grasses are adapted over a large area (tall fescue, bluegrass, orchard grass). However, the breeder of tropical grasses may be faced with making a choice among many species, each of which may only be suited to a relatively small land area. For example, past research in Florida has concentrated primarily on digitgrass (. Digitaria deoumbens Stent.) and bermudagrass ( Cynondon dactylon (L.) Pers.) but, more recently, several other grasses such as 1 impograss ( Hemarthria altis- sima (Poir.) Stapf et C. E. Hubb.), elephant grass ( Pennisetum purpureum Schum.), buffelgrass ( Cenchrus ciliaris L.), guineagrass (Panicum maximum Jacq.), Rhodes- grass ( Chlorida gay ana Kunth) , pearl millet ( Pennisetum amerioanum (L.) K. Schum.), and species of Bracharia and Paspalum have been evaluated. Some of these pasture grasses have shown promise, and breeding for improved yield and quality is being conducted. We believe that early generation evaluation of germplasm by grazing animals will facilitate more rapid and efficient selection of the germplasm best adapted to Florida pastures. The first phases of evaluation will be carried out in the absence of graz- ing animals because emphasis in this stage is simply on reaction to environmen- tal conditions. Reaction of the plant to defoliation must also be assessed. V/here large numbers of different genotypes are involved, clipping is often the easiest method. Since it is well known that the effects of cutting and grazing may differ greatly, early generation testing under grazing can emphasize bene- j ficial or detrimental traits of the grass. SCHEME FOR FORAGE BREEDING AND EVALUATION At Florida, the cooperating plant breeders, forage management specialists and animal scientists have developed a scheme for testing and evaluating for- ages. This scheme emphasizes early generation animal testing of new genotypes. J Although the exact techniques and procedures may vary according to the type of forage being evaluated, the scheme can be divided into four main phases. Phase I: Evaluation of Plant Introductions and Breeder Lines The plant breeder is responsible for implementation of phase I. This phase may involve testing new species for tolerance to particular environmental conditions such as winter hardiness, disease and nematode susceptibility, and tolerance to temperature and moisture stress. It may also involve any of the , more sophisticated breeding techniques for recombination of genetic material in | species of proven adaptab i 1 i ty . Plant material in this phase will generally be , 100 evaluated as single plants or progeny rows with sufficient space allowed for development of sto 1 on i f erous or rhizomatous grasses. With certain breeding schemes, such as polycross progeny testing, evaluation of breeder lines in small plots may be necessary. The agronomic measurements recorded in this phase will be determined by the particular objectives for a species and may include persistence, yield in- crease, pest resistance, regrowth, mode of reproduction, and seed set. Forage quality measurements in this phase may include chemical composition, in vitro organic matter digestibility, analysis for toxic substances, and leaf-stem ra- tios. This phase will mainly be conducted at the home base of the breeder with perhaps some testing at a second site. Phase II: Regional Adaptation in Small Plot Clipping Trials The plant material in phase II will include only superior genotypes from phase I. In a state such as Florida with wide climatic extremes, this phase requires the cooperation of agronomists at several branch stations. The plant breeder may also choose to distribute certain selected lines to cooperating scientists from other states in the region. Data collected from phase II ex- periments could be used as supplemental justification for release of selected genotypes as new cultivars. Testing of plant material in phase II should be conducted in enough locations to determine its area of adaptability. Primary consideration will be given to plant response to climatic and soil conditions, varying levels of f er t i 1 i za t ion , and varying intervals of defolia- tion. Other parameters to measure at this phase will include seasonal yield, total yearly production, and response in grass legume mixtures. Forage quality- including I VOMD and chemical compostion, should be measured under the different environments and management schemes. Phase III: Forage Response to Grazing Animals Phase III involves plant defoliation and trampling by grazing animals. The plant material used in this phase may be identical to that in phase II or it may be select material from phase II. We feel that if phase II and phase III testing are conducted concurrently, the time from introduction to cultivar release will be shortened. This phase will require close cooperation between the plant breeder and the forage management specialist. It will also require development of several specialized small paddocks for restricting grazing ani- mals to selected plants. Selective grazing is one of the difficulties to be considered when evalu- ating forage plants under grazing. If only a few animals are placed in a pad- dock and allowed to stay for one or two weeks, the more palatable genotypes may receive a much more severe defoliation than the less palatable types. This problem may be overcome by "mob grazing". This technique involves confinement of a large number of animals to small paddocks and forcing the animals to graze all entries to a uniformly close height in two to four days. Although this type defoliation is different from that obtained under continuous grazing, it is similar to what could be experienced under rotational strip grazing and in- troduces the effects of trampling, pulling on the plants, and feces and urine. Since pastures under commercial conditions are likely to receive abuse, our goal with this mob grazing treatment is to determine which genotypes will with- stand rather severe management. 101 Grazing management treatments may also be imposed in phase III on selected lines. The three main variables in any grazing management scheme are days of rest, days of grazing, and grazing pressure. The number of plots required to evaluate the practical range of these variables using routine experimental de- signs would be unmanageable. However, Mott and coworkers have shown that through use of the response surface designs, the number of pastures can be kept reasonably low while still evaluating the range of grazing management variables. This technique has proven particularly valuable in evaluating the effect of grazing management on the persistence of legumes at variable grazing pressures in newly developed grass cultivars. The response surface design has also been utilized to estimate which system of defoliation will result in maximum produc- tion of digestible energy. The effect of the various management regimes on I VOMD and other quality parameters should also be determined in phase III. Phase IV: Animal Response to Forages The objective of phase IV is to determine animal performance on potential new forage cultivars. The measurements will be taken to estimate animal gain per land area, carrying capacity per land area, voluntary intake, nutrient di- gestibility, forage quality prediction models, and forage yield in terms of feed units. Successful completion of this phase requires major assistance and cooperation from supportive animal scientists. Two types of studies are possible in phase IV. The first would be an in vivo feeding trial. The objectives of this type of study would be to measure forage quality in terms of voluntary intake, in vivo digestibility, and rate of passage. Additional outputs from in vivo studies may be improved laboratory techniques for quality evaluation and development of models for forage quality pred i ct i on . The second type study in phase IV will be grazing trials where the mea- surements are in terms of animal gain, carrying capacity, and effect of the forage on reproductive efficiency. Various systems of management, including continuous or rotational grazing and supplemental feeding, may be evaluated. Phase IV grazing experiments may also be designed to evaluate animal perfor- mance on new cultivars used as conserved forage such as silage, hay, or field stockpiled forage. Animal gains under various grazing pressures may also be evaluated. Phase IV studies utilizing animals as a tester are very expensive to conduct and should be designed to obtain the maximum information possible. I SUMMARY A scheme for evaluation of tropical and subtropical forages in the short- est possible time should involve animal evaluation in early generation testing. We propose that phase III (plant response to grazing animals) testing be initi- ated concurrently with phase II (regional adaptation in small plots) testing. This early generation evaluation of plant response to animals, coupled with im- plementation of phase IV (animal response to plants) testing at the earliest date possible, will help to shorten the time to variety release. ACKNOWLEDGEMENTS The authors would like to acknowledge the advice and cooperation of the entire forage breeding and management faculty of the Agronomy Department of the Unversity of Florida. The ideas presented in this paper are a synthesis of in- 102 puts from plant breeders, forage management specialists, and animal scientists. Special recognition is given to Dr. G. 0. Mott for the original outline of the scheme which has been discussed in this paper. SCHEME FOR FORAGE EVALUATION Phase I Plant Introductions and Breeder Lines Preliminary testing of introductions and elite lines Two locations Adaptability Spaced plants Pest tolerance Reg i ona 1 Selection of Adapted Types \ w Phase II Phase III Small Plot Trials Plant Response to Animal Five locations Soil factors Small plots Climatic factors Fertility S clipping Management Two locations Sma 1 1 paddocks Defol iat ion response Response to grazing management Selection of Elite Lines 'f Phase IV Animal Response to Forage Two locations Animal gain Large pastures Carrying capacity Voluntary intake and nutrient digestibility 103 BREEDING APOMICTIC GRASSES By P. W. Voigt, B. L. Burson, and M. C. Engelke At one time, apomixis (asexual reproduction from seed) was regarded as a block to breeding progress and an evolutionary deadend. However, research over the past 20 years has demonstrated that this is not true (Bashaw, 1975). Facultative apomicts maintain their ability to produce new genotypes through occasional sexual reproduction. De Wet and Harlan (1970) have dia- grammed the complex interrelationships within an agamic complex. Their research suggests how contact with sexuality can be maintained even across ploidy levels through diploid-tetraploid-haploid cycles. Thus, sexual forms j through hybridization can generate new apomictic forms which can later revert to sexuality through haploidization. Obligate apomictic biotypes are completely isolated from each other. However, contact can be reinitiated when sexual forms are found. In some species, diploid forms are a source of sexuality (Burton and Forbes, 1960). In others, recovery of sexuality may depend on- the discovery of rare mutant plants (Taliaferro and Bashaw, 1966). New genotypes can then be generated and both sexual and apomictic types recovered. Based on the genetic research reported in the literature, workable breeding schemes have been proposed for a number of apomictic grass species. The purpose of this paper is to present these schemes and to compare their efficiency in production of potentially useful apomicts. We will also present breeding schemes for Eragrostis curvula (Schrad.) Nees, based on our assess- j ment of the present genetic knowledge of this species, and point out areas where additional evidence is needed. Bahiagrass, Paspalum notatum Flugge At the tetraploid level, bahiagrasses are normally obligate apomicts. However, induced tetraploids, from sexual diploids, reproduced sexually. Burton and Forbes (1960) used them as females in crosses with the apomictic tetraploids. They concluded that "obligate apomixis was controlled by a very few recessive genes." Based on their results, the following breeding scheme could be proposed. Sexual X Apomict (2.5-25) T (i) Sexual X Apomict i T Apomict f Sexual 1 Apomi ct 104 The exact ratio resulting from the initial cross could vary from 2.5 to 25 sexual for each apomict (Burton and Forbes, 1960). The genetic constitution of both parents influenced the frequency of apomictic hybrids. Thus, because the desired new cultivar would be an apomict, the choice of parents producing a high frequency of apomictic hybrids would be essential if high efficiency was to be obtained. Sexual hybrids could be self pollinated to produce additional apomicts. However, F2 plants from sexual hybrids were reduced in vigor (Burton and Forbes, 1960). The frequency of apomictic F2's was also low, ranging from 1 apomict for each 30 to 230 sexual. Thus, self-pollination of sexual hybrids would not appear to be a viable breeding scheme for bahiagrass or for other species where inbreeding depression occurs. A third potential breeding scheme would be to intermate sexual hybrids. Depending on the exact genotype, a certain number of apomictic plants might result, but most would probably be sexual. Thus, recurrent selection for yield or other characters could be attempted. Such an approach might provide access to the variability found among the naturally occurring apomictic tetraploids. Efficiency would depend on the ease of intermating. Sterility caused by cytological irregularities (Forbes and Burton, 1961) or other problems could limit the usefulness of this approach. Buffel grass, Cenchrus ciliaris L. The inheritance of apomixis in buffelgrass and the closely related bi rdwoodgrass Cenchrus setigerus Vah 1 . has been clearly demonstrated (Taliaferro and Bashaw, 1966; Read and Bashaw, 1969). Results from hybridi- zation between sexual and apomictic plants, and self-pollination of a sexual plant supported a two gene model, "where gene B conditions sexuality, and it is epistatic to gene A which conditions obligate apomixis." Two potential breeding schemes were described. Sexual X Apomict 0.7) I (1) Sexual X Apomict * “1 Apomi ct Sexual “1. Apomict Sexual (4.3) O) r Sexual Apomict f Sexual ~1 Apomict 105 Clearly, the higher frequency of apomicts makes the hybridization scheme more efficient than the self-pollination scheme. However, sexual buffelgrass plants must be hand emasculated to produce the hybrids (Taliaferro and Bashaw, 1966). Apparently, sexual buffelgrass is normally self-pollinated and does not show inbreeding depression to the extent observed in bahiagrass (Burton and Forbes, 1960) or other normally cross-pollinated species. The cultivar 'Higgins' (Bashaw, 1968) was produced from self-pollination of sexual plant TAM-CRD B-ls. Thus, in buffelgrass both breeding schemes are viable approaches. Ratios obtained could vary with different sexual or apomictic genotypes. Apomictic breeding schemes can also be more effective than sexual schemes because apomixis can provide an escape from sterility. Read and Bashaw (1969) found that apomictic buffel -bi rdwoodgrass hybrids had 81 % O.P. seed set com- pared to 42% for sexual hybrids. The value of apomixis, as an escape mech- anism from sterility in interspecific and even some intergeneric crosses, has been demonstrated in several species, e.g., Harlan (1966); Dale et al . (1975). Compared to bahiagrass, except in the need for hand emasculation, the breeding schemes now in use with buffelgrass appear more efficient than those possible with bahiagrass, because buffelgrass produces a higher percentage of apomictic offspring. Kentucky Bluegrass, Poa pratensi s L. The inheritance of apomixis in Kentucky blueg-rass, a facultative apomict, is not well understood. Different hypotheses have been proposed which range from apomixis as recessive to sexuality and due to a delicate genetic balance (Muntzing, 1940) to two complementary dominant genes required to make a plant moderately to highly apomictic (Funk and Han, 1967). The absence of a precise understanding of the inheritance of apomixis has not prevented its effective manipulation. In terms of released varieties (Funk et al . , 1973; Funk et al . , 1974; Peterson et al . , 1975), the Kentucky bluegrass program at Rutgers University has been more effective than any other apomictic grass breeding program. Although several breeding schemes have been proposed (Brittingham, 1943; Funk and Han, 1967), the most effective has been: Apomict X (partly) Apomict (highly) Par iy Apomictic l flp0,llict Partly Apomictic Highly Apomictic “1 Highly Apomictic Highly sexual types have been developed and could be used as females but many of the most promising hybrids have been "triploids," plants from ferti- lization of an unreduced egg with reduced pollen (Pepin and Funk, 1971). All three released cultivars, * Adel phi , ' ' Bonniebl ue , ' and 'Majestic' were derived in that way. This increase in chromosome number has limited the effectiveness 106 of the recurrent hybridization approach because plants with more than 100 chromosomes are usually reduced in vigor (Pepin and Funk, 1974). The efficiency of apomictic breeding of Kentucky bluegrass can be quite high. Hybrids are not difficult to produce under controlled environmental conditions (Pepin and Funk, 1971). The choice of female parents determines the balance in efficiency between percentage of hybrids that are highly apomictic (potential cultivars) and percentage of plants that are maternal and not of hybrid origin. Also, the higher the level of apomixis in the parents, the greater the frequency of highly apomictic hybrids from the fertilization of reduced or unreduced eggs (Funk and Han, 1976). Old World Bluestems, Bothriochloa , Dichanthi urn, and Ca pill ipedium In the agamic complex of old-world bluestems, the diploids are usually sexual, the tetraploids are facultative apomicts, and the higher polyploids are almost completely apomictic (Harlan et al . , 1962). Sexual tetraploids were obtained by crossing a diploid X apomictic tetraploid (from fertilization of an unreduced egg) and an apomictic tetraploid X apomictic tetraploid (Harlan, 1966). From their genetic studies Harlan et al . (1964) concluded that apomixis was, "controlled by no more than one gene per genome." Apomixis was dominant to, but independent of, sexuality. From these results, two potentially useful schemes were proposed (Harlan, 1966). Sexual X Apomictic 0) (3) T Sexual X Apomict A Partly Apomictic X Apomict F Sexual V Partly Apomictic 1 Highly Apomictic l Highly Apomictic Apomict X Apomict (1) Sexual X Apomict T (15) T Sexual Unlike bahiagrass, apomixis However, if the potentially more T 1 Partly Apomictic I Partly X Aoomict Highly Apomictic i Hpomlct Apomictic — q Highly Apomictic can be easily recovered in the hybrids, useful apomict X apomict cross is to be ----- , i - j — — — — . . — — — — — — tried, hand emasculation and pollination would probably be necessary and large 107 populations would have to be screened to separate maternal types from hybrids. Hybrids can also be produced from fertilization of unreduced eggs. This would increase the percentage of apomictic hybrids above 94% expected from the second scheme. Possibly, the efficiency of hybrid production from facultative apomicts could be increased by manipulating the environment to increase sexual repro- duction. Knox and Heslop-Harrison (1963) found up to 79% apomictic embryo sacs in Dicanthium aristatum (Poir.) grown under short days. Under long days the maximum percentage was only 47%. Thus, more hybrids from reduced eggs should be produced from pollinations of plants growing under a long day than a short day. A small effect of environment on percentage apomictic plants, 86% to 93%, was observed also in Poa pratensis (Hovin et al . , 1977). Guineagrass, Panicum maximum Jacq. Guineagrass must be considered a facultative apomict because, despite the uniformity of many introductions, a low level of sexual reproduction occurs in natural populations (Warmke, 1954; Bogdan, 1963). Hybrids were produced by crossing sexual plants obtained from facultative apomicts or doubled diploids 1 with apomictic plants (Smith, 1972; Hanna et al . , 1973; Perenes and Rene- Chaume, 1973). Most results published to date are in agreement with the two loci hy- pothesis concerning the genetics of apomixis proposed by Hanna et al . (1973). Two dominant alleles or more produce sexuality and one or no dominant alleles result in apomixis. Breeding schemes were proposed (Burton et al . , 1973; Smith, 1974; Pernes et al , 1975). Sexual X Apomict (1) (1) T Sexual X Apomict r-* Sexual 0PartT. X Apomict Apomictic ^ K 1 Highly Apomictic J Partly Apomictic Sexual X Sexual Highly Apomictic (2.2) (1) T 4 Sexual X Sexual v Partly Apomictic X Apomict f Sexual r Partly Apomictic i Highly Apomictic Highly Apomictic 108 The apomictic breeding system is highly efficient. Hybrids appear relatively easy to produce (Hanna et al . , 1973) and a relatively high per- centage of apomicts (50%) can occur in the Fj. Other genotypes could have different efficiencies in the production of apomicts. For example, an apo- mict, homozygous recessive at both loci, when crossed with sexual plants of the genotype reported by Hanna (AaBb) should produce three apomictic F x 1 s for each sexual Fx. Efficiency of apomictic breeding is reduced because some of the apomictic F x ' s may have a higher level of sexuality than most naturally occurring apomictic strains (Perenes and Rene-Chaume, 1973). Self- or cross-pollination of sexual plants would not be as efficient in the production of apomicts, because of the lower ratio of apomictic to sexual plants. Other possible sexual genotypes would produce even fewer apomictic offspring in the first generation. Weeping Lovegrass, Eragrostis curvula (Schrad.) Nees. The inheritance of apomixis in _E. curvul a has not been determined. However, we have collected enough data to devise potential breeding schemes. Our results indicate that sexual plants, when self-pollinated, produce only sexual plants, as determined by cytological and progeny tests (Voigt and Bashaw, 1976). Of course, we cannot rule out the possibility that other sexual genotypes may exist that would segregate for mode of reproduction when self-pol 1 inated. Numerous lovegrass hybrids have been produced. Our data indicate that the hybrids can be either sexual or apomictic (Voigt and Bashaw, 1976). Based on progeny tests, our present data suggest that the ratio is between 1.2:1 and 1.7:1 of sexual :apomictic F^s, respecti vely . Other crosses may give dif- ferent results. The accuracy of progeny testing to determine mode of reproduction in a facultative apomict, such as E_. curvul a , is open to question. Our results suggest that in some cases, misclassifications can occur. We are using cytological data to determine the accuracy of our progeny tests. The value of progeny testing in determining mode of reproduction may vary with the amount of sexuality of the facultative apomictic parent(s). The amount of sexuality varies among hybrids, e.g., 6% to 24% sexual (Voigt and Bashaw, 1976). Although we have not attempted to determine the amount of sexuality of natural ecotypes of E_. curvula , the fact that until recently £. curvula was considered an obligate apomict (Voigt and Bashaw, 1973; Brix, 1974) suggests that the level is usually very low. Potentially useful breeding schemes for E. curvula are: Sexual X Apomict (1.4) (1) Sexual X Apomict Sexual Partly X Aoomict Highly Apomictic | Mpomici Apomictic V Partly Apomictic 1 Highly Apomictic 109 Sexual X Sexual Sexual X Sexual X Sexual i i etc. etc. The efficiency of the apomictic breeding scheme for E_. curvula is similar to that for P_. maximum. The advantages, relative ease of hybridization and a relatively high percentage of aporni ct hybrids, and the disadvantage of facul- tative apomixis, are the same. Because the inheritance of aporni xis in E_. curvula is not completely understood, we cannot predict what affect other genotypes than those already tested may have on the sexual to apomict ratio. Research is continuing in this area. A second scheme involves interbreeding sexual plants. We cannot be sure, from present knowledge, that a totally sexual population can be developed at the tetraploid level. We are beginning research to find out. This scheme is one easily adapted to recurrent selection. Although recurrent selection usually has not been considered for use with apomictic species, it could be useful to increase the frequency of desirable genes for quantitatively inherited chracteri sties . The efficiency of this approach would depend on having genotypes that produce few or no apomictic offspring when intercrossed. If too many apomicts resulted, progeny tests would have to be used to detect apomictic plants, which could then be eliminated. This would reduce the effecti venesss of the procedure, because of the increased time and expense of these tests, unless a recurrent selection program for general or specific combining ability was desired. Summary: Apomictic breeding schemes can be more effective than sexual schemes. Apomixis can serve as an escape from sterility, thus, allowing use of a wider diversity of germplasm than is possible with sexual species. Each highly apomictic hybrid is a potential cultivar that can perpetuate hybrid vigor. Apomictic cultivars need only the minimal isolation distances required to prevent mechanical contamination. Their uniformity results in more uniform seed ripening than in many sexual species, thus, aiding in seed harvesting. However, this same uniformity could provide a uniformly susceptible host for a disease or insect. This possibility should be countered by developing and releasing several cultivars, where wide spread use is anticipated, and by using several cytoplasms and numerous diverse genotypes in the breeding program. Efficiency among apomictic breeding schemes depends on several factors. 1) The ease with which new, potentially useful apomictic genotypes can be created through crossing or selfing, 2) The frequency of occurrence of these genotypes in the created populations, and 3) The amount of sexuality in the apomictic hybrids. When facultative apomicts are used as cultivars, the occurrence of aberrant plants is of concern. Where uniformity is of great importance, such as in turf, only the most apomictic plants can be considered for use as 110 cultivars. Breeder's increase fields should be space-planted so they can be effectively rogued. Seed increase probably should be limited to the founda- tion and certified classes. Any consistent effect of environment on amount of facultative apomixis could be exploited. Higher levels of sexuality would be of great benefit in production of hybrids. Environmental manipulation to reduce the level of sexual reproduction in a facultative apomict would be of benefit to increase accuracy of progeny tests used for classifying mode of reproduction , and in achieving cultivar uniformity. Some apomictic species produce a high percentage of sexual plants from certain sexual by sexual crosses. In these species the use of recurrent selection should be considered. References Bashaw, E. C. 1968. Registration of Higgins buffelgrass. Crop Sci. 8:397- 398. Bashaw, E. C. 1975. Problems and possibilities of apomixis in the improve- ment of tropical forage grasses, p. 23-30. In. E. C. Doll and G. 0. Mott, ed.. Tropical Forages in Livestock Production Systems. Am. Soc. Agron. Special Publ . No. 24. Bogdon, A. V. 1963. A note on breeding behavior of Panicum maximum in Kenya. Trop. Agric. 40:313-314. Brittingham, W. H. 1943. Type of seed formation as indicated by the nature and extent of variation in Kentucky bluegrass and its practical impli- cations. J. Agr. Res. 67:225-264. Brix, K. 1974. Sexual reproduction in Eragrostis curvula (Schrad.) Nees. Z. Pfl anzenzuchtg 71:25-32. Burton, G. W. and I. Forbes, Jr. 1960. The genetics and manipulation of obligate apomixis in common bahia grass (Paspalum notatum Flugge). Int. Grass!. Congr. Proc. 8:66-71. Burton, G. W., J. C. Mill ot , and W. G. Monson. 1973. Breeding procedures for Panicum maximum Jacq. sguggested by plant variability and mode of repro- duction. Crop Sci. 13:717-720. Dale, M. R. , M. K. Ahmed, G. Jelenkovic, and C. R. Funk. 1975. Character- istics and performance of interspecific hybrids between Kentucky blue- grass and Canada bluegrass. Crop Sci. 15:797-799. de Wet, J. M. J., and J. R. Harlan. 1970. Aoomixis, polyploidy, and speci- ation in Dichanthium. Evolution 24:270-277. Forbes, I., Jr., and G. W. Burton. 1961. Cytology of diploids, natural and induced tetraploids, and intraspecies hybrids of bahiagrass, Paspal urn notatum Flugge. Crop Sci. 1:402-406. Funk, C. R., R. E. Engel, G. W. Pepin, A. M. Radko, and R. J. Peterson. 1974. Registration of Bonnieblue Kentucky bluegrass. Crop Sci. 14:906. Funk, C. R., R. E. Engel, G. W. Pepin, and R. A. Russell. 1973. Registration of Adel phi Kentucky bluegrass. Crop Sci. 13:580. Funk, C. R., and S. J. Han. 1967. Recurrent intraspecific hybridization: a proposed method of breeding Kentucky bluegrass Poa pratensis. New Jersey Agric. Exp. Stn. Bull. 818, p. 3-14. Hanna, W. W. , J. B. Powell, J. C. Mill ot , and G. W. Burton. 1973. Cytology of obligate sexual plants in Panicum maximum Jacq. and their use in controlled hybrids. Crop Sci. 13:695-697. Ill Harlan, J. R. 1966. The use of apomixis in the improvement of tropical and subtropical grasses. Int. Grassl . Congr. Proc. 9:191-193. Harlan, J. R., M. H. Brooks, D. S. Borganonkar, and J. M. J. De Wet. 1964. Nature and inheritance of apomixis in Bothriochloa and Dichanthium. Bot.. Gaz. 125:41-46. Harlan, J. R., H. R. Chheda, and W. L. Richardson. 1962. Range of hybridi- zation with Bothriochloa intermedia (R. Br.) A Camus. Crop. Sci . 2:480- 483. Hovin, A. W. , C. C. Berg, E. C. Bashaw, R. C. Buckner, D. R. Dewey, G. M. Dunn, C. S. Hoveland, C. M. Rincker, and G. M. Wood. 1977. Effects of geographic origin and seed production environments on apomixis in Kentucky bluegrass. Crop Sci. 16:635-638. Knox, R. B. and J. Hesl op-Harrison . 1963. Experimental control of aposporous apomixis in a grass of the Andropogoneae. Bot. Notiser 116:127-141. Muntzing, A. 1940. Further studies on apomixis and sexuality in Poa . Hereditas 26:115-190. Pepin, G. W., and C. R. Funk. 1971. Intraspecific hybridization as a method of breeding Kentucky bluegrass (Poa pratensis L.) for turf. Crop Sci. 11:445-448. Pepin, G. W. , and C. R. Funk. 1974. Evaluation of turf, reproductive, and disease-response characteristics in crossed and selfed progenies of Kentucky bluegrass. Crop Sci. 14:356-359. Pernes, J. and R. Rene-Chaume. 1973. Genetic analysis of sexual and apo- mictic Panicum maximum. Genetics (special issue, 13th Congress of Genetics, Berkeley) 74:2:2: 210. Pernes, J., R. Rene-Chaume, J. Rene, and Y. Savidan. 1975. Schema d 'amel ioration genetique des complexes agamiques du type Panicum. Cah 0RSTR0M ser. Biol. 10:2:67-75. Peterson, R. J., G. W. Pepin, and C. R. Funk. 1975. Registration of Majestic Kentucky bluegrass. Crop Sci. 15:885. Read, J. C. and E. C. Bashaw. 1969. Cytotaxonomic relationships and the role of apomixis in speciation in buffelgrass and birdwoodgrass . Crop Sci. 9:805-806. Smith, R. L. 1972. Sexual reproduction in Panicum maximum Jacq. Crop Sci. 12:624-627. Smith, Rex L. 1974. Breeding Panicum maximum. Soil & Crop Sci. Soc. Florida Proc. 34:103-106. Taliaferro, C. M., and E. C. Bashaw. 1966. Inheritance and control of obligate apomixis in breeding buffelgrass, Pennisetum ciliare. Crop Sci. 6:473-476. Voigt, P. W. , curvul a . Voigt, P. W. , curvula . Warmke, H. E. and E. C. Bashaw. 1973. Agron. Abstr. 65:16. and E. C. Bashaw. 1976. Crop Sci. 16:803-806. 1954. Apomixis in Pani Facultative apomixis Facultative apomixis cum maximum. Amer. J. in Eragrosti s in Eragrosti s Bot. 41 : 5-11 . 112 THE OKLAHOMA BERMUDAGRASS BREEDING PROGRAM: OBJECTIVES AND APPROACHES By C. M. Taliaferro, W. L. Richardson and R. M. Ahring INTRODUCTIONS AND OBJECTIVES With the development and release of 'Coastal' and 'Midland' bermudagrasses in 1943 and 1954, respectively, (2, 8) the image of bermudagrass was trans- formed from that of a dreaded "cotton patch" weed to that of a highly desirable pasture and conservation-use grass. The initial plant breeding work with ber- mudagrass in the U.S. was conducted, of course, by Dr. Glenn W. Burton, ARS Geneticist at the Coastal Plains Experiment Station, Tifton, Ga. It was his efforts largely, if not entirely, that gained due recognition for this impor- tant grass. Genetic research with bermudagrass and other Cynodon species began in Oklahoma in the early 1960 's. During that time Jack Harlan, J. M. J. deWet and W. W. Huffine made independent plant collection trips and amassed a worldwide collection of Cynodon germplasm (more than 700 accessions) at the Oklahoma State University. They conducted an extensive biosystematic study of the genus from 1963 to 1967 which elucidated phylogenetic relationships and eventually led to a revised taxonomic classification of the genus (9, 10, 11, 12, 13). In 1968, after Dr. Harlan's departure from OSU to a new post at the University of Illinois, the decision was made to begin a genetic improvement- varietal develop- ment program utilizing the vast and diverse storehouse of Cynodon germplasm that he and his colleagues had accumulated. The objectives of this breeding program are rather straightforward with the main emphasis on increasing the nutritive value while maintaining, and hopefully increasing, yield potential and adaptability. The good points and the bad points of widely grown bermuda- grass cultivars like Coastal and Midland have been rather thoroughly discussed and characterized in the literature (4, 5, 7). Briefly, their high forage pro- duction potential per unit area together with their ability to persist under continuous and close grazing are, perhaps, their greatest assets. Their low or, at best, intermediate production potential per grazing animal is undoubted- ly their greatest liability. It is toward an increase in this potential that our efforts are primarily directed. A somewhat secondary, but potentially important, endeavor in which we are involved is the development of winterhardy seed producing, seed propagated bermudagrass cultivars. These might be used for pasture purposes if their overall agronomic performance is competitive with vegetatively propagated cultivars but they should definitely be useful in establishing quick and permanent ground cover on areas where the primary con- cern is soil stabilization. 113 THE GERMPLASM BANK Harlan's (10) revised classification of the genus Cynodon is presented in Table 1. He has discussed each of the 8 listed species and ten varieties in terms of their value for grazing and hay (14). The species and varieties that we are primarily using in our breeding program at present are: (2. dactylon varieties dactylon and afghanicus , (2. aethiopicus and (2. nlemfuensis varieties nlemfuensis and robustus . Plants that are winterhardy and well adapted to Oklahoma come from the two varieties of (2. dactylon . The latter two species represent robust East African types which, in general, seem to have the highest nutritive value but are not winterhardy. Major differences between the temperate and tropical types are listed in Table 2. The major task before us, obviously, is to genetically incorporate the desirable attributes of the two types into an agronomically acceptable cultivar. All of the species and varieties listed are highly cross-pollinated, genetically heterozygous and heterogeneous and rather easily crossed at the varietal and species levels. Cynodon dactylon var. dactylon is enormously variable but from the temperate germplasm available in this taxon we have yet to find a plant with outstanding nutritive value. However, I would wholeheartedly agree with Burton (6) who recently expressed his belief that the potential is excellent for developing high quality, winterhardy bermudagrass cultivars. As he pointed out both characters are heritable, parents excelling in one or the other of these characters are available and there is no evidence indicating that they are incompatible . THE APPROACH Vetetatively Propagated Bermudas Crosses between temperate, low quality and tropical, high quality Cynodons! produce variable progenies whose average values for hardiness and quality usually approach the midparent value. In large hybrid populations, however, individual plants can usually be found which equal, and sometimes exceed the hardiness or quality of the parent excelling in the respective trait. Unfor- tunately we have not as yet found a single hybrid plant excelling in both characteristics. Winterhardiness is undoubtedly conditioned both by rhizome production and by tissue hardiness. The species CH aethiopicus and (2. nlem- fuensis are nonrhi zomatous . Although we have attempted no genetic study of the inheritance of rhizome production we have backcrossed hybrid plants to hardy parents and selected from these backcross progeny rhizomatous plants with reasonably good hardiness. These selected plants -retained some of the characteristics of the tropical parents eg. certain morphological character- istics, fast initial spread potential and most significantly, a reasonably increased level of quality. As an example, in 1973 we selected from 900 such progeny five genotypes which we have subsequently yield tested for two years in a preliminary trial on one of our research stations near Chickasha, Okla- homa. The forage yields of the five selected genotypes plus that of the variety 'Hardie' are given in Table 3. The best hybrid, 71 X 6-7, has yielded 26% more forage than Hardie, this being a statistically significant difference. 114 Table 1. A revised classification of the genus Cynodon* Epithet Chromosome Number Distribution C. aethiopicus Clayton et Harlan 18, 36 East Africa: Ethiopia to Transvaal C. arcuatus J. S. Presl ex C. B„ Presl 36 Malagasy, India, S. E. Asia. S. Pacific to Australia C. barberi Rang, et Tad. C. dactylon (L.) Pers. 18 India var. dactylon var. afghanicus Harlan 36 Cosmopolitan et deWet 18, 36 Afghanistan var. aridus Harlan et deWet 18 South Africa northward to Palestine, east to South India var. coursii (A. Camus) Harlan et deWet 36 Madagascar var. elegans Rendle 36 Southern Africa, south of lat . 13° S. var. polevansii (Stpnt) Harlan et deWet C. incompletus Nees 36 Near Baberspan, S. Africa var. incompletus 18 Transvaal to Cape var. hirsutus (Stent) deWet et Harlan C. nlemfuensis Vanderyst 18, 36 Transvaal to Cape var. nlemfuensis 18, 36 Tropical Africa var. robustus Clayton et Harlan 18, 36 East Tropical Africa C. plectostachyus (K. Schum.) Pilger 18 East Tropical Africa C. transvaalensis Burtt-Davy 18 South Africa *After Harlan, J. R. (10) 115 Table 2. Major Differences Between Temperate and Tropical Cynodons . Character Temperate Tropical Initial spread Slow Fast Rhizomes Abundant Few to none Tenacity Strong Weak Nutritive value Lowest Highest Table 3. Yields of Chickasha, Five Bermudagrass Selections Oklahoma 1975-76. and the Variety Hardie Selection Tons Dry Matter/Acre or 1975 1976 75-76 % of Variety 3-cuts 2-cuts Avg. Hardie 71 X 6-7 5.56 5.09 5.32 126 71 X 8-3 5.31 4.22 4.77 113 71 X 8-4 5.23 4.23 4.73 112 71 X 11-5 5.08 4.14 4.61 109 71 X 306 4.48 4.21 4.34 103 Hardie 4.88 3.57 4.23 100 116 The pedigree of 71 X 6-7 traces to an original cross between a well adapted, rhizomatous, temperate parent and a nonrhi zomatous , tropical parent as j follows: 71 X 6-7 I (Guymon X A 8153) X SS - 16 Guymon = C_. dactylon var. dactylon A 8153 = (2. dactylon var. afghanicus A 9958 = (2. dactylon var. dactylon A 8800 = (2. dactylon var. afghanicus A 10421 = C. dactylon var. robustus 6-X-820 X A 9958 A 8800 X A 10421 In addition to its apparent good yield potential 71 X 6-7 has exhibited in this one preliminary trial a rapid establishment capacity, the formation and maintenance of a reasonably thick and uniform sod and a spring recovery and spring growth capability not too different from that of conventional cultivars such as Midland and Hardie. Tentative measurements of its quality are however, conflicting, some indicating excellent quality while others indicate only a modest level of digestibility. The SS-16 plant list above is also an interesting hybrid. It has better than average quality and the robust growth potential of its tropical parents, along with abundant rhizome production and good winterhardiness. Its robust growth potential usually is exhibited only during the year of establishment. In subsequent years, its forage yield has been disappointingly low except under conditions of high N fertilization and irrigation in dry periods. However, we believe that 71 X 6-7 and other progeny that we have selected from crosses involving SS-16 as a parent demonstrate that it does not transmit this low yield characteristics to all of its progeny. I believe that these results further demonstrate that progress is being made in the incorporation of desirable attributes from the temperate and tropical Cynodons into individual genotypes. The key to even- ! tual success appears to be continued energetic efforts in breeding and utili- zation of the best selection and evaluation tools that we have available. The IVDMD and NBDMD procedures for estimating forage quality have been of immense value in selecting for higher forage quality, but still faster methods are needed that will allow breeders to evaluate even larger numbers of progeny i plants. Seed Producing-Seed Propagated Bermuda Research We have identified and isolated Cynodon accessions and hybrids from our germplasm collection that have good seed set and good seed production poten- tial. In an initial study conducted in 1971-72 the best of these fertile selections produced 2-year average open-pollinated seed yields of 969 Kg/ha (1). 117 These and other fertile clones that we have subsequently identified and selected are cross fertile but highly self-incompatab le with the majority of the clones setting less than 1.0% seed when selfed. We have found a few clones that consistently set a much higher than average percentage of seed under self-pollination indicating that the intensity of the self-incompat- ibility mechanism does vary in bermudagrass . We have used select fertile bermuda clones to produce experimental synthetic varieties which are now in the initial stages of evaluation. Two clone synthetics, generated by planting alternating strips of two fertile clones in seed production fields have been produced for four different clonal combinations. Seed production from these fields has been quite acceptable for the past two years ranging from 400 to 700 lbs/A. As Burton (3) suggested this would be an ideal way to commercially produce Fi hybrid seed, the essential prerequisites being sufficiently fertile parents to make it econom- ically feasible and, of course, an Fj hybrid population with acceptable per- formance characteristics. Open-pollinated progeny from our clones and synthetic varieties are, as expected, highly variable both in terms of morphology and fertility. We have initiated breeding work designed to increase the level of fertility and other desirable characteristics in this germplasm. LITERATURE CITED 1. Ahring, R. M. , C. M. Taliaferro, and R. D. Morrison. 1974. Seed produc- tion of several strains and hybrids of bermudagrass, Cynodon dactylon (L.) Pers. Crop Sci. 14:93-95. 2. Burton, Glenn W. 1943. Coastal bermudagrass. Circ. 10 Ga. Coastal Plains Expt. Sta. (Revised 1948, pp. 21). 3. and Richard H. Hart. 1967. Use of self-incompatability to produce commercial seed-propagated Fj bermudagrass hybrids. Crop Sci. 1 7:524-527. 4. , and R. S. Lowrey. 1967. Improving forage quality in bermudagrass by breeding. Crop Sci. 7:329-332. 5. , J. E. Jackson, and R. H. Hart. 1963. Effects of cutting frequency and nitrogen on yield, in vitro digestibility and protein, fiber, and carotene content of Coastal bermudagrass. Agron. J. 55:500-502. 6. . 1972. Potential for development of high quality, winterhardy bermudagrass varieties. In Report of the Twenty-Ninth Southern Pasture and Forage Crop Improvement Conf . , Clemson, S. C. pp. 70-71. 7. Elder, W. C. and H. F. Murphy. 1961. Grazing characteristics and clipping response of bermudagrass. Okla. Agric. Expt. STa. Bull. B-577. 118 8. Harlan, J. R. , G. W. Burton, W. C. Elder, 1954. Midland Bermudagrass . A new variety for Oklahoma pastures. Okla. Agric. Exp. Stn. Bull. B-416 (PP- io). 9. _, J. M. J. deWet. 1969. Sources of variation in Cynodon dactylon (L.) Pers. Crop Sci. 9:774-778. 10. , , W. W. Huffine, and J. R. Deakin. 1970. A guide to the species of Cynodon (Gramineae) . Okla. Agric. Exp. Stn. Bull. B-673 . 11. , , and K. M. Rawal. 1970. Origin and distri- bution of the seleucidus race of Cynodon dactylon (L.) Pers. var. dactylon (Gramineae). Euphytica 19:465-469. 12. , , , N. R. Felder, and W. L. Richardson. 1970. Cytogenetic studies in Cynodon L. C. Rich. (Gramineae). Crop Sci. 10:288-291. 13. , , and W. L. Richardson. 1969. Hybridization studies with species of Cynodon from East Africa and Malagasy. Am J. Bot. 56:944-950. 14. Harlan, J. R. 1970. Cynodon species and their value for grazing and hay. Herbage abstracts 40:233-238. 119 i THE PROPOSED ESTABLISHMENT OF HAY STANDARDS By R. F Barnes, D. A. Rohweder, and N. Jorgensen Hay is big business in the United States. Over $6.5 billion worth of ha} was produced in 1975 (JL ) . Over 20 percent of the hay is marketed as a cash crop that is eventuallv fed to livestock. Wide variations in the percentage of hay sold exist among States. In Arizona and California approximately 75 percent of all hay is sold off the farm where produced; in Wisconsin, the largest hay producer in the United States, less than 10 percent is normally sold off the farm. Increasing feed costs in the face of continuing demands for ruminant livestock products have focused attention on the real and poten- tial value of the Nation's hay crop. HAY MARKETING TASK FORCE In 1972 the American Forage and Grassland Council (AFGC) formed a Hay Marketing Task Force to (a) identify hay marketing problems, (b) determine problem priorities and possible practical solutions, and (c) develop specific recommendations for action. A Forage Analysis Subcommittee was given the charge of establishing a system for pricing hay based upon some realistic measurement of feed value. Numerous reports have been prepared and talks given based upon the Subcommittee's findings ( _2 , _5, 9_, 10) . In April 1975 the Subcommittee cosponsored a Hay Quality and Analysis Roundtable (7) at Beltsville, Maryland, which set the stage for the develop- ment of two important programs. The use of infrared reflectance for esti- mating chemical composition of forage samples was first reported at that meeting. The information presented has been subsequently published (6). The potential for such instrumentation continues to be promising, and an update on its current status was reported earlier in this conference. At the same meeting, the merits of revising the Federal hay grades were considered, and a decision was made to pursue the establishment of new hay standards based upon chemical composition as related to animal response data. The present Federal hay grades were authorized by the Agricultural Marketing Act of 1946 and were last revised in the Handbook of Official Hay and Straw Standards in 1949 (4) . These grades are based on organoleptic properties (subjective properties based upon color, texture, odor, and flavor), leafiness and botanical composition and on the presence or absence of foreign material. These are all qualitative properties subject to variable scoring and to erroneous estimates of feeding value. At present the func- tions associated with the inspection and standardization of grain and hay have been transferred from the Agricultural Marketing Service to the Federal Grain Inspection Service (FGIS). The FGIS was established by PL94-582 as of November 1976. Today there are only a half dozen qualified hay inspectors 120 in the United States, and less than 300 lots of hay were inspected this past year. FORAGE ANALYSIS SUBCOMMITTEE In 1974 the Forage Analysis Subcommittee surveyed U.S. scientists and extension personnel working with forage quality and animal nutrition to obtain a consensus of opinion relative to more precise techniques for evaluation of forage quality. The majority of the respondents indicated that analyses for acid detergent fiber (ADF) and neutral detergent fiber (NDF) (3) were the chemical assays of choice for estimating _in vivo digestible dry matter (DDM) and dry matter intake (DMI) , respectively. The subcommittee obtained forage samples with known analytical data from a number of locations to determine the precision of the above relationships. Data, including ADF, NDF, and the in vivo measurements of DDM and DMI, were obtained from Florida, Indiana, Wisconsin, and Pennsylvania (9_, 11) . The plant species included in the ini- tial study were alfalfa (Medicago sativa L.), smooth brome (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), reed canarygrass (Phalaris arundinacea L.), tall fescue (Festuca arundinacea Schreb.), 'Pangola' digit- grass (Digitaria decumbens Steut.), bahiagrass (Paspalum notatum Fliigge) , and 'Suwannee* bermudagrass (Cynodon dactylon (L.) Pers.). The relationships of chemical composition to iri vivo measurements were estimated by regression analysis. A combination of ADF and NDF were used to provide an estimate of digestible dry matter intake (DDMI) for a forage as follows : DDM (%) is inversely related to ADF concentration; i.e., DDM decreases as ADF increases. DMI expressed in terms of animal body weight in kilograms to the 0.75 power is inversely related to NDF concentration; i.e., DMI decreases as NDF increases. DDMI, expressed in the same terms as DMI, is equal to DDM X DMl/100. PROPOSED MY STANDARDS The new hay standards proposed by the Forage Analysis Subcommittee (9, 11) are presented in Tables 1 and 2. Legumes, grasses, and legume-grass mixtures are evaluated in a continuum, allowing a calculation of feeding value for all types of plants. Both organoleptic characteristics and repre- sentative chemical analyses (crude protein, ADF, and NDF) are used to estab- lish five grades with one sample grade. The grades are based on advancing stages of maturity and are designed to represent measurable differences in animal response. The knowledge that the intake potential of hay can be just as important as digestibility led to consideration of these two characteris- tics in combination to give an estimate of DDMI. The DDMI was then used to predict the relative feed value by which an equitable pricing system can be established. Relative feed value is calculated from DDMI by multiplying the latter by 2.5 (a DDMI value of 40 is arbitrarily designated as a relative feed value of 100) . The formulas used to calculate relative feed value are 121 TABLE 1. — Proposed market hay grades for legumes and legume-mixtures (Hay Marketing Task Force). 0) O X Pn X > 0 $ 1 1 o B X 3 0) 3 1 1 X rH X 0 3 «H 0 pH > A CM i-M O i — 1 VI Mi 4-1 g ptf CO X X Pn 3 0 3 X X 3 Q 0^ X CO g'S 0 1 — 1 0 0 •H 3 V •H Ph o * A •H CO 0 CM 0 i — i — * 1 CO V X 3 0 3 U 3 rH 1 — 1 Mi X Mi X 3 i — i 3 O 3 X - B X CO > 3 0 X X 0 Mi X 0 X 3 X O 3 > 0 3 O 0 a) 0 CO 3 3 « 3 Mi X CO i — i Pl CO 0 0 0 00 X 00 CO X 3 0 0 0 4-» 0 •H P^ g'S rH 3 •H r. X •H X 0 0 rH Mi 0 Ml 0 4-1 m o 0 Mi 0 Mi X > 4M 00 Mi CO i — i B O Mi O 0 X 0 3 3 •H . c r- O 3 £ Mi O X s X 4-1 o X X 3 P . r 4-1 4-1 4M B o 3 4M X X o 3 3 CO 3 O 0 1 1 CO rP r-H 3 o CO X B X •H ■ — 1 •rH 0 cd 3 oo g>8 * rH X . r. g's pn 3 0 c 0 4-1 Mi •H X •H o X 0 4-1 0 o 4-1 o * 3 CO B Ptf CL 00 Mi i—4 1 — 1 »— l P^ 0 o CMl CM CO •H X 00 3 •H 0 o CO Mi Ml cO 3 X 0 X X X . » X • « Ml Mi • «> 3 B • ft CO 4M 0 0 3 B o X 0 0 M O cd O \ 3 0 > 3 3 3 Mi CO X 0 CO «N| B X CMl 4M 1 — 1 • r 3 X X CJ O 3 CO P 0 w o c h 4-1 O CO i — 1 4-» 0 4-1 o Mi X O 0 •H Q 0 P 0 a 0 . t~ 3 CO X O #v •H 00 PH > 00 p> CO 0 M) > 3 •H 3 CO 0 g'e X 00 rH cd •H 4-1 3 CO 0 0 3 0 Ml X g'S CO 0 a X o 3 3 X cd 0 0 CO 0 0 Mi 0 0 0 O 0 Mi •H X CM X CO 3 a rH Mi 3 1 — 1 rH 4m r- < — 1 Mi 4-1 r> CO 1 — 1 X X O X 0 0 •rH O B 4-1 oo 3 Mi o B 3 3 X 00 CO g'S 4M g*$ CO g^S B O 3 4-1 3 0 3 x >-> o r m 3 i — 1 3 O o X 3 3 X 'w" * X 0 > X 0 4= LO S'S X , 0 3 3 X X 3 00 r 4-1 CJ 3 H3 X 4-1 3 B II 0 O O 4-4 Mi X 0 X O PH 4-1 0 O CO 0 a cd o rP X r Ml •H 0 X g 4-1 B 4—1 3 CO X O CO IX o 0 o •H 4-1 CO 0 3 lx rH 00 00 0 o 4M 3 3 oo Pn X 3 u cd 3 00 rM o 0 3 O 3 4-1 3 QJ 4-1 •H 0 3 P 00 rH •H B -H X 3 P CO 3 Mi 4-1 CM 3 PL Mi 3 X 0 3 x •H 3 O CO 4M \ 4-» X 3 X 3 X 0 0 pH • » •H 4M o i— 1 CO 4M 3 •x 3 X 2 Mi 00 0 . r. B o O 3 4-1 CT 3 3 O X 3 0 0 P B 3 rP o • *» >» •H 3 S O i — 1 3 o £ P o O a 0 B 0 0 0 £ •H 0 •H o 4-> o •H •H rM o Mi X X X o P>, X i — 1 00 4-1 i — i 0 CO rH 1 Ml P X o O O I — 1 X 3 rH X •H <4M Mi 3 P 3 £ rH B X r X U •H 0 P 3 •r-) •H 3 P 3 0 X Pn X X •H 4-1 X 4J 3 •rM Mi B 3 CJ 0 X 3 3 0 4-1 CO CO O •H ■H •H 1 1 0 o 3 Ml 4-1 O a X Q 0 Mi B 4-1 B 3 0 rH o B Mi 3 a 0 O Q •H 0 •rH 0 Mi 3 CM rH o 4-1 U 3 X 3 X X 4m 4-1 0 00 o 00 3 4M \ X o •H 0 O 0 •H CO 4-1 3 4-> 3 3 rH X 3 Ml 4-1 CO CJ 3 0 O 3 *H 0 4-1 CO O 3 X 0 CO CO g'S ix < 4-1 P 00 B 0 CO 4-1 4-1 X •H 3 X X 0 /-N o a 3 O r— 1 3 3 u X 3 3 X X 0 CM Pn 11 XI •rH O O Mi 4-1 X 3 X •H 0 X X 3 CL X V 3 3 r3 i — 1 rH 3 0 3 rH •H X Mi 3 4-1 CO X 3 X 3 PH CQ 5 0 P W rP 3 X g 3 Pm CO x 0 X q 0 •H CO 00 IX Mi X CO •H •H O 0 Mi 0 0 o 0 0 . - B O X CO B, X $ 0 3 X pn 3 0 •H *-w Pn rH CO Mi £ rH X 3 0 Q x 1 cd 3 O 3 X CJ P 0 X CO •H X 3 B B B B i — 1 B •H X r 3 0 X o 0) u 0 o Mi 0 o rH O X O i — 1 o 3 o 3 X X 3 •H X 0 OO 3 4-1 •H 0 Mi o Mi o •H o 3 o " — M X X 3 O > PH rH 3 4-1 3 4-1 H PM rH 3 1 — 1 g 1 — 1 Pm I — 1 COj 3 0 CO i — 1 3 3 •H 0 P 4-1 3 M cd P PJ rP X X d) o X d 3 g X 0 3 co g 3 X u X X 0 #• X X X H 3 3 •H P>% g'S o P 3 Mi X 3 - £ X CO CL Of] X 0 CJ o O 0 0 Q rH o •H CJ 0 •rH X CL X V X rH CO 0 0 0 0 0 X X X CJ PH CO II B B B B X 0 Mi 3 3 3 3 PL 0 X 3 PH 00 pn 00 >, 00 00 Pn B •r—) 0 1—1 1 X CM CO CJ 0 0 0 3 0 3 0 3 0 3 3 3 X > •H 0 P2 X P r3 P P P X X X C/3 X O O X X 3 cd O 3 X Mi »H X 3 cj i — 1 CM CO a) CN O CO •H O X X 0) i — 1 l — 1 Pi X 3 3 C*J 5h Pu X S 3 CJ CO > X Oh 3 O 3 X X X 3 3 Q ft 3 X CO 3 pH 3 3 i — 1 ■3 | o in 3 3 X ^5 X P-. m X in 4-1 •H 3 CO •rH a cn 1 i X •rH 3 X 1 — 1 X V m r— 1 A 3 4-1 c n V CO i — 1 1 — 1 1 m X •H CO 3 3 6^ 4-4 W 00 a o 3 5-4 cn •rH x •H 1 X O Q o B X 3 fp 3 3 CO pH 4-1 X 3 X 3 X o pH cn X pH 3 3 3 3 O cj •H Q cn i 1 X Pi X co X < V X A 4-1 3 CJ O X 3 1 — 1 •H X X X 3 X 3 H 3 CO Pi Pi Pi ft co a O O 3 3 £ 3 60 •H CU 3 4-> o '•d- X 3 CU B /"-V S CO X i — 1 •H Oh O 3 •H X V CO X H CJ 00 CM Pi pH O •H 3 N I 00 pH pH co 3 pH £ 3 PH 1 — 1 1 1 V £ X X CN 3 x cj A X 00 X 3 3 3 cd pH H X o X 3 < — 1 s 3 CM X 3 ft X * X 3 X > 5-4 3 Pi 3 3 a X 3 cd CO 4H 3 o 3 O X 3 3 X CJ 3 X X 3 O 3 X 3 X 3 X X 3 CJ 3 3 3 3 O 5-i 3 O 3 O 4-1 3 X 3 pH 3 5-i 00 00 00 O Pi CO 3 Pp co 3 00 •H Oh •rH On 4-1 5-4 CO X 3 3 3 CU 3 • X H 3 4-» [3 3 4-> 3 O X Pi X X 3 x 3 4-4 O 4-1 Pi CO O Pi CO 3 00 X 3 >n O 3 O > 3 3 QJ 4-1 HP O 3 pH O 3 3: •rH o 3 r — 1 £ 3 in •rH x O 3 • #N 3 00 4h £ pH 4-1 £ O 3 5 X O r/j X X •H X 1 1 •H 3 Pi 5-4 Oh 3 5-i r — 1 o 3 3 3 •X 4-1 00 cd #> i — 1 ^8 r- *> X O 4-1 CO X O X 3 X pH X pH £ CU •H 4-1 o X m X 4-1 CO 3 3 > rO 3 3 •H . 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X Oh 3 4—1 00 00 CO CO 3: 3 •H 3 3 i — 1 CO 2 3 00 3 X X Ph 3 4D x 00 pH Pi CO 3 3 3 3 - CJ X 3 3 3 a o O 3 4-1 X CJ 3 a 3 3 X 3 3 — 4-1 5-i HP CJ CO 3 3 3 £ •rH X 5-4 pi •H £ 3 X 3 CJ •rH X >H 3 3 •x CO CO O 4-1 3 •H 3 00 X ■rH 3 o 00 H 3 O 3 £ 3 3 r3 X •X cd O 3 CO X i — 1 3 3 a 3 3 3 1 1 3 4-4 3 X a X CO O S 3 Pu ,3 •H B O 3 • X 4-1 i — 1 CJ 3 3 CO x £ 00 1 X •- •x X X 3 u 4-1 O 3 4-1 3 X 3 •H CO 2 00 3 CO 5-i O 3 X 2 X CO 3 4-1 5-4 3 CJ 3 X O X x •H 4-1 4-1 2 3 •H 4-1 3 3 5-4 O 4-1 4-1 00 3 X •H 3 o £ 3 X Ph o pH 3 3 3 CO 3 3 3 5-i vO 4-1 o 3 4-1 CO 3 3 4-1 3 3 X a Q 4-4 3 •H 3 4-» m HP 3 3 O CO rH X o 00 CO 3 4-4 X ft 3 Z i — 1 00 x 4-1 > Jd 3 5-4 pH o 4-4 4-1 pH . r. X 3 3 O Oh X 3 •H X pH x cd 3 •H a 00 c On 3 00 4-4 4-1 3 < — 1 X 4-J > 4-1 X X o •rH 3 B Q 4-1 •H 3 4-1 pH HP 3 3 x* •H X 3 3 3 44 CO 5-4 O 3 X •rH 3 Oh 3 X 3 Hd O 5-4 5 •H •H 4-> 3 4—1 HP 3 CO 4-1 5-4 CO £ £ 3 i — 1 4-1 3 Pi £ CO •rH 00 3 4-1 3 o o 3 •H HP 3 O 3 CO •rH o X CO 3 3 o CO X O > 4H < x 3 00 00 X 4-> 3 4-1 a HP X £ X X Pi 00 X In £ 3 3 X pH 3 3 X 3 X 4-1 3 3 3 o 4-1 CO •H 4-1 3 4-1 3 X 00 3 3 CJ 5-4 5-i 3 3 X X X X O Oh II i 3 4-1 •H 3 o 3 3 HP 3 3 Pi 3 3 3 3 o 3 3 O O X 3 Oh Cu X •rH 3 3 i X CO 3 X PD i — 1 •x 2 3 DP O 3 CO 3 Pi Q CO 3 3 £ 4-1 X X 3 3 Oh x 3 Pu CO 4-1 3 3 3 X O q CM 3 •rH CJ CJ X £ 00 X 4-H 5-4 3 CO 3 X •H O w 4-) Oh rH O 5-1 X 3 O •rH co 3 X . X O x 1 3 £ O pi CO CJ 2 3 £ 3 3 3 PD •H x 3 B CO Oh CO X CJ •X < Ph pH Xl 3 3 i — 1 CO N 1 — 1 •rH CO 3 X d) O X X 3 •rH •rH 3 X 3 3 3 X 3 X a CJ O i — 1 CJ X X X X H 3 3 •rH •rH ^£ •H •rH O 00 X 3 5-i X 3 X £ X CU CU 00 X 3 CJ a O 5 3 X o o X •rH CJ 3 •rH •rH X X o 3 X X o pH cn 3 X 4-J ft CJ 3 CN Ph H Ph Pu cn II CO CO CO CO pH s CJ Oh X CO CO CO CO CU 3 X X V N Ph 3 3 Oh 3 Oh 3 In 3 In £ •r~> CO 1 — 1 3 cNlcn 1 m 1 so 1 CJ 3 X 3 5-i X 5-1 3 5-4 3 3 3 X 3 S n X X o HP CJ HP cj X CJ X C/d X o X 3 3 Oh X X Pi X 3 3 CJ CN cn Hf n X o 3 M 123 presented in footnote to Table 3. They were derived from regression analyses of DDM and DMI data for forages of known composition fed to sheep. The organoleptic descriptions used in the old standards are used only as descriptive characteristics rather than as absolute grade determinants. Con- sideration is also given to moisture level and to injurious foreign material (toxic or noxious weeds and hardware) as secondary characteristics that may affect hay quality and value. Typical concentrations of crude protein (CP) , ADF, and NDF for the vari- ous stages of maturity in legumes and predominantly legume mixtures are given in Table 1, and those for grasses and predominantly grass mixtures in Table 2. If expected CP values are not reached or if moisture and/or quantities of foreign material exceed set limits, a basis exists for lowering the grade established by prediction of digestible dry matter intake alone. CP concen- tration is important to nutriment and is often positively correlated with energy availability, but CP is not considered a primary factor in calculating i relative feed value because climate and fertilizer may modify this relation- ship in forages. The best pure grass hays will usually grade no higher than a grade 2 legume hay. This is because grasses usually contain far more NDF and have lower intake potential than legumes. At low levels of nitrogen fertilizer, grasses also contain less CP than legumes. HAY PRICING Relative feed values range from over 140 percent for early-cut legumes to | less than 83 percent for late-cut grasses. If one assumes a base price of $50 , per ton for a mature legume hay having a relative feed value of 100 (Grade 4) , hay prices will range from less than $42 per ton to over $70 per ton, depend- ing on quality. The base price can readily shift with the current market situation in localized areas. This system would provide a far more equitable determination of hay price than that currently existing. A comparison has been made between the proposed market hay grades and actual sales of 268 lots of hay in Wisconsin in 1976 (Table 4) (8 ) . These lots could be identified according to stage of maturity and other character- istics into the five proposed hay grades. A significant aspect of the information is that the range in market price within any one grade was con- siderably greater than would be anticipated for that specific grade. For instance, the range in value for grade 4 was $32 to $100 with the upper limit exceeding the average price for grade 1. The value based on corn at $2.50 per bushel or soybeans at $10 per hundredweight and relative feed values are also given. PRESENT STATUS It must be recognized that the proposed hay standards are in the process of evolving. Further, it is urged that flexibility be allowed in updating the proposed standards as more data become available. The availability of samples for which there is adequate animal data and reliable information about agro- nomic characteristics is limited. Also, subtropical species may not fit the 124 TABLE 3. — Typical composition of Digestible Dry Matter (DDM) , Dry Matter Intake (DMI) , and Digestible Dry Matter Intake (DDMI) for proposed market hay grades described in Tables 1 and 2— 04 o X3 • &-? > 3 1 3 Csl| Pm •H 3 3 •H 0) eA O co o Q > 1 1 1 3 > o CM o <£ 3 3 •H 4-J •H X) 1 1 1 I 1 ! — 1 CO 3 P 3 4-J o 4J CD T— 1 1 1 i 00 M 3 3 3 3 0) CD A r— I m V 4-J 3 3 P T— 1 Pc 3 CM o 00 OJ 00 ii 3 3 CL) 1 1 1 1 i — 1 o • •H 3 3 X) P 03 • x 3 3 > o in p B 3 r— 1 cd p o 3 3 1 II 3 3 > P^ 3 4-4 r-H PO m 6^ M 3 3 X) 3 o- PM X 3 • X) > 3 3 o Q Q P 3 3 3 3 O 5 P 4-J 3 4-4 3 ov o • n cd 3 P M 00 1 ON <1- CO LiOOJ • -r> 4-J 1 1 H 3 X P 1 i i CO o- m 3 3 > 3 Q 1 A r— 1 co V OP Pm • *H 3 •rH 3 O S CO O Q CM 1 1 • 4— > P o 3 3 P cd 3 B X 3 3 3 i — i •rH 00 + < — 1 4-J 3 3 XJ CTv 1 — 1 4-J co P X m X cd •H 3 4-J CO • o p B O Ph m in • p 4-J O • cd vO o kO 1 — 1 4M P 3 p • II 3 3 3 o il 1 X) X) O 3 CO ctv VO vD Ol X IPS 3 3 p’'* 4— i 3 O 3 X P 1 vO 1 1 m Q P-( r-H 1 1 4-J 3 3 Cl Q 1 A m Ov V Q Q 3 P •H 3 > o 3 vD m 1 <3 > *H T— | 3 •H X 1 4-J 3 3 i — 1 r-H B CD P 33 CO 3 s 3 00 6 LO 3 3 cr 4M O 3 • 3 PO 3 o PO CM Pm •H 3 O 3 CD 33 00 •H 3 P 3 + 3 3 4-J 3 4-J o > II 3 *H 3 > OJ r-H 00 •H O 3 3 3 •H X 1 04 VO LfO • • • +j M 4-J O 3 •H > Q e^s 1 i 1 m 0) 3 X P 1 1 Q 1 A 04 uO V 3 CO 1 1 p I 1 B o 3 3 vO m rH 3 p 1 1 o PO M 3 ii P 3 CJ \ — 1 3 > • b 4-1 in 3 Q o cd O O 3 3 1 1 — 1 4-J 3 O 3 • 4-1 1 \ 3 P P 4H P o CO M •H O 4-J CTv 3 3 X 4M 3 M 00 r- LO 1 — 1 i > CO P 3 3 o 4-J 3 X P in i i i •H CO 3 4-J 3 3 Q A o r— 1 j i 4-J cd X 4M 3 CO •H P Q 3 m 3 3 4-J B 3 3 < 1 o X 3 •rH PO P B 3 p B p cd O X PO 3 p 3 3 3 PO CM Po 3 O P 3 3 t^-S II 3 4H P 3 CO Pm X) 3 3 3 X m 3 p M 3 3 3 cd 1 1 3 X II 3 P^ P • 3 p 3 P r-H 3 o CD O p M •H 3 i — 1 1 1 0) o 1 1 1 1 X 3 P b M PO o CO 00 i 3 • r, p 3 3 D •H 3 X P CO i i vO i u ooj 3 3 c r 4-J PC Q A m 00 V i • 5-5 • r> 1 1 4-J 3 3 0) 3 P o o Pm X 3 4— J 3 P \ 4-j p 4-J > cd 3 00 B 1 3 •rH B 3 •H PO t? i — 1 "O 3 X) 3 b*s vO •H 3 p^ CO Pm p 3 3 X 4-< 3 p « — I •H 4H X) 3 o 3 o 4-J P O CO • CO 3 4-J 4-J 3 > o IT) cd 00 o 3 > O P •H X o vO 00 i 1 — 1 vO PO •H 3 > a e-? i 1 m i 3 • 1 •rH 4-J X 3 4-J Q A vO 00 V i £ 04 T3 3 4-> 3 3 3 P in P-i &-? 1 — 1 •H > •rH M O + P4 3 3 i — 1 3 Pm p 3 P •H 3 3 CTv 3 4-1 p o P \ CO 4-T\ •H p 4-J ' — 1 1 OJ 3cm 1 4-J CD II 04 B 3 • r\ CO X) • 3 3 3 3 1 1 04 CO m M i — 1 X PO > 4-J 3 X 3 •H *rH 3 O P + x) X) 4-J B 125 TABLE 4. — Comparative identification of hay grades with selected hay sales in 1976^/ Grade No . of Lots (%) Average Price ($) Range in Value ($) Value Based on Corn $2 . 50/bu Soybeans $10/ cwt . | Value Based on Relative Feed Value ($) 1 26 (10) 84 62 - 110 $84 > 84 2 68 (25) 75 50 - 125 75 74 - 84 3 80 (30) 65 37 - 90 65 60 - 74 4 67 (25) 58 32 - 100 60 50 - 60 5 27 (10) 44 30 - 75 45 < 50 Total 268 _!/ Compiled Dec. 8, 1976, by Dr. D. A. Rohweder. 126 proposed standards; however, it may be possible to use hemicellulose values to overcome any discrepancies that may occur. Alternative approaches to the implementation of a hay grading system may include (a) the establishment of new Federal hay grades to be monitored by the FGIS through a cadre of trained hay inspectors, (b) the establishment of new Federal hay grades by the FGIS to be used by an established trade association, by commercial laboratories, or by the Cooperative Extension Service, or (c) the establishment of hay grades under the auspices of a trade association that could then be monitored by the association. The proposed hay standards have been submitted to the FGIS for their review. At this time, it is not known which of the approaches, or what additional approach, might be pursued. However, it is unlikely that the proposed standards will be adopted in final form sooner than 2 years from now. Meanwhile, it is urged that the proposed assays be used so as to further test their validity in obtaining realistic estimates of the feeding value of hay for marketing and feeding programs. It is essential that a rapid, accurate, and relatively inexpensive analytical procedure be available for use in any effective hay marketing situation. It is hoped that the infrared reflectance technique will meet this need. SUMMARY The Hay Marketing Task Force of the American Forage and Grassland Council has proposed a new system for establishing feeding value and equitable market pricing of hay. The system consists of five market grades plus a sample grade that would replace an outdated and cumbersome system of establishing Federal hay grades devised in the 1940’s. The new system is based upon the concept of defining feeding value according to chemical composition as related to animal response. The two primary determinants are concentrations of acid detergent fiber (to estimate digestibility) and neutral detergent fiber (to estimate intake potential). Other characteristics that would determine a given grade include stage of maturity, crude protein concentration, moisture level, and degree of contami- nation with injurious foreign material. An expression of relative feed value is calculated from an estimate of digestible dry matter intake to permit an evaluation of all hays on a con- tinuum. An equitable price for the hay can then be calculated from a localized base price for a Grade 4 hay that has a relative feed value of 100. To make the new system workable, faster assays of fiber components and crude protein are needed for small lots of hay that are in transit. 127 REFERENCES 1. Agricultural Statistics, 1976. U.S. Department of Agriculture, U.S. Government Printing Office, Washington, DC. 2. Barnes, R. F. 1975. Predicting digestible energy values of hays. Proceedings of Laboratory Methods and Services Workshop. May 20-22, 1975. Salem, OR. Cosponsored by the Association of American Feed Control Officials, Inc. — Association of Official Analytical Chemists (AAFCO-AOAC) . 3. Goering, H. K. and P. J. Van Soest. 1970. Forage fiber analysis. Agriculture Handbook No. 379, Agricultural Research Service, U.S. Department of Agriculture. 4. Handbook of Official Hay and Straw Standards. 1958. Grain Division, Agricultural Marketing Service, U.S. Department of Agriculture. (Revised July 1, 1949). U.S. Government Printing Office, Washington, DC. 5. Moore, J. E. , E. J. Golding, III, and R. F. Barnes. 1975. (Revised April 1975). Assessment of applicability of present methods of predicting digestible energy values of hays. Prepared for AFGC Research Committee and Hay Marketing Task Force. 6. Norris, K. H. , R. F. Barnes, J. E. Moore, and J. S. Shenk. 1976. Predicting forage quality by infrared reflectance spectroscopy. J. Anim. Sci. 43:889-897. 7. Report of Hay Quality and Analysis Roundtable. April 28-30, 1975. Beltsville, MD. 8. Rohweder , D. A. 1977. Personal communication. 9. Rohweder , D. A., R. F. Barnes, and N. Jorgensen. 1976. The use of chemical analyses to establish hay market standards. Paper presented at the First International Symposium on Feed Composition, Animal Nutrients Requirements, and Computerization of Diets. July 11-16, 1976. Logan, UT. 10. Rohweder, D. A., R. F. Barnes, and N. Jorgensen. 1976. A standardized approach to establish market value for hay. Agron. Abst. p. 112. 11. Rohweder, D. A., N. Jorgensen, and R. F. Barnes. 1976. Using chemical analyses to provide guidelines in evaluating forages and establishing hay standards. Feedstuffs 48(47) :22-58 (November 15). 128 SOUTHERN FORAGES IN THE NEW HAY STANDARDS By John E. Moore The proposal of new hay quality standards by the American Forage and Grass- land Council (AFGC) is an important step forward in the practical application of forage quality principles. The new standards are based upon voluntary Di- gestible Dry Matter Intake (DDMI). This parameter is closely related to Di- gestible Energy intake and animal performance, and is an acceptable measure of overall forage quality. The objective of this paper is to discuss tropical grasses used for hay in the South in terms of the AFGC standards. Intake, digestibility and hay grades based upon actual rn vivo trials will be compared to similar values predicted by AFGC equations based on chemical composition. FORAGES AND ANALYSES This study involved 82 hays of eight tropical grasses: Pensacola and Paraguay 22 bahiagrass (Paspalum notatum); Alicia, Coastal, Coastcross I, Common and Suwannee bermudagrass (Cynodon dac tylon) ; and Pangola digitgrass (Digitaria decumbens). The hays were harvested in Florida and Louisiana after regrowths ranging from 2 to 12 weeks and fed to mature wether sheep in indi- vidual digestion cages. Dry matter digestibility (DMD) and dry matter intake (DMI) were measured. Samples of each hay were analyzed for acid-detergent fiber (ADF) and neutral-detergent fiber (NDF). These values were used to compute a predicted DMD and DMI for each hay using the following AFGC equations: DMD , % = 34.8 + 2.56 (ADF ) - .0491(ADF)2 7 5 2 DMI,g/BW = 54.8 + 1.22 (NDF ) - .0176(NDF) DIGESTIBILITY AND INTAKE Figures 1 through 6 illustrate the relationship between chemical composi- tion and actual in vivo data for each of the 82 hays. Superimposed on each figure is a solid line representing predicted values according to AFGC equa- tions . There was a close relationship between predicted and actual DMD of Florida Pangola digitgrass and Pensacola bahiagrass (Fig. 1). However, AFGC equations overestimated the DMD of Suwannee bermudagrass (Fig. 1) and Louisiana forages (Fig. 2 and 3). The data suggested that ADF may not be a generally acceptable predictor of DMD. Florida data suggested that there was a relationship between NDF and DMI for Pangola digitgrass, but the AFGC equation did not describe this relation- ship (Fig. 4). For Florida Suwannee bermudagrass (Fig. 4) and the Louisiana forages (Fig. 5 and 6), the AFGC equation underestimated DMI. The data sug- gested that NDF may not be a generally acceptable predictor of DMI. HAY GRADES 1 In the AFGC system, hay grades are based upon DDMI(g/BW" ) which is the product of DMD times DMI. The following standards have been proposed: 7 5 Grade DPMI , g/BW* 1 >56.0 2 49.6 - 56.0 3 40.1 - 49.5 4 34.0 - 40.0 5 <34.0 In this study, DDMI was calculated in two ways: (1) using actual DMD and DMI values, and (2) using predicted DMD and DMI values. Figures 7 and 8 illus- trate the relationships between predicted and actual DDMI values for the Florida and Louisiana hays, respectively. Superimposed upon Figures 7 and 8 are the divisions between grades. For the Florida hays (Fig. 7) many samples were in Grade 5 according to both predicted and actual DDMI. However, there were a number of discrepancies in which predicted grades were lower than actual grades. Eight samples of Suwannee bermudagrass and Pangola digitgrass were in Grades 2 and 3 according to actual DDMI, but no predicted grades were above Grade 4. In addition, six hays in Grades 2, 3, or 4 according to actual DDMI were predicted to be in Grade 5. Similar results were obtained with the Louisiana hays (Fig. 8). Although only 12 samples were in Grade 5 according to actual DDMI, 34 were predicted to be in Grade 5. As in the Florida hays, no Louisiana hays were predicted to be above Grade 4 although 25 of 51 hays were in Grades 1, 2, or 3 according to actual DDMI. In addition, there was much less variation in pre-- dieted than in actual DDMI values. CONCLUSIONS 1. The proposed AFGC hay quality standards are based upon a sound concept: voluntary intake of digestible dry matter (or digestible energy). 2. The equations proposed by AFGC for prediction of dry matter digestibility and intake are generally unacceptable for tropical grasses, especially bermudagrass : a. digestibility is overestimated. b. intake is underestimated. c. ADF and NDF are often not closely related to digestibility and intake, respectively. 3. For tropical grasses, predicted DDMI and hay grades based on AFGC equation: do not vary as much as do actual jin vivo DDMI and grades, and the quality of higher-quality hays is underestimated by AFGC predictions. 130 More rational, and perhaps complex, models are necessary in order to apply the AFGC hay grades to tropical grasses in the South. t . ACKNOWLEDGEMENT Data on the Louisiana forages were provided by Dr. Billy D. Nelson, Dairy Nutrition, Southeast Louisiana Dairy and Pasture Experiment Station, Louisiana state University, P. 0. Drawer 567, Franklinton, LA 70438. FIGURE 1. — Relationship between dry matter (DM) digestibility and acid detergent fiber of Florida Pensacola bahiagrass, Suwannee bermudagrass and Pangola digit- grass (solid line represents predicted values based on AFGC equations). 131 FIGURE 2. — Relationship between dry matter (DM) digestibility and acid detergent fiber of Louisiana bahiagrasses (solid line represents predicted values based on AFGC equations) . FIGURE 3. — Relationship between dry matter (DM) digestibility and acid detergent fiber of Louisiana bermudagrasses (solid line represents predicted values based on AFGC equations) . 132 FIGURE 4. — Relationship between dry matter (DM) intake and neutral detergent fiber of Florida Pensacola bahiagrass, Suwannee bermudagrass and Pangola digitgrass (solid line represents predicted values based on AFGC equations) . FIGURE 5. — Relationship between dry matter (DM) intake and neutral detergent fiber of Louisiana bahiagrasses (solid line represents predicted values based on AFGC equations) . 133 FIGURE 6 .--Relationship between dry matter (DM) intake and neutral detergent fiber of Louisiana bermudagrasses (solid line represents predicted values based on AFGC equations) . 50 : LPi CD Q □ "D toAia}> Le.p-icU.um viAginicum Ipomca 6p. SteZlaAia media Lamium amptcxicauic Vigitcmia Aanguinalii Baachicuiia platypkylia Vaciytoctcnium acgyptium Panicum tcxanum SciaAia 4p. 145 TABLE 4 . --Inf luence of Chemical Weed Control on Bahiagrass Production Location Chemical Percent Broad- leaf weeds after 75 days Dry Matter Yield lbs Bahiagrass/Ac . Percent of Check Jefferson Co. Check 92.0 635 Banvel 0.0 3005 473 Weedmaster 0.0 2984 470 Pearl River Co. Check 79.4 748 — Banvel 0.0 5156 698 Weedmaster 2.0 4703 628 TABLE 5. — Value of Weed Control in Bahiagrass Per Acre Increase lbs . Value Attributed to Location Chemical Bahiagrass as Hay 1/ Spraying Jefferson Co. Check 635 6.35 Banvel 3005 30.05 $23.70 Weedmaster 2984 29.84 $23.49 Pearl River Co. Check 748 7.48 Banvel 5156 51.56 $44.08 Weedmaster 4703 47.03 $39.55 1/ Based on a value of $20.00 per ton for unharvested forage. 146 TABLE 6. --Effect of Weed Control on the Quality of Bahiagrass Location Chemical Percent Lignin Percent Digestible Dry Matter Jefferson Co. Check 13.2 43.1 Banvel 6.8 50.8 Weedmaster 6.1 49.7 Pearl River Co. Check 9.2 48.5 Banvel 5.9 58.0 Weedmaster 5.9 57.2 TABLE 7.- •-Effect of Weed Control on the Crude Bahiagrass forage Protein Content of Location Chemical "6 Crude Protein lbs. /Ac 1 / Value^ / Increase Attributed to Spraying Jefferson Co. Check 7.4 46.8 9.36 Banvel 8.1 242.2 48.40 $39.04 Weedmaster 7.9 235.1 47.02 $37.66 Pearl River Co. Check 10.7 79.6 15.92 Banvel 10.9 564.0 112.80 $96.88 Weedmaster 10.4 491.0 98.18 $82.26 1 /Protein yield calculated from D. . M. yield X % crude protein. 2 /Protein value assumed to be 20C/lb. as this is the approximate cost of a pound of protein from cottonseed meal. 147 EFFECTS OF GRAZING MANAGEMENT ON A SMUTGRASS-BAHI AGRASS-WHITE CLOVER SWARD By William R. Ocumpaugh Smutgrass ( Sporobolus pozretiz (Roem. and Shu It.) Hitch.) has become a serious threat to improved pastures of the southeastern states including Florida. A recent survey in Central and South Florida counties indicated that 75% of the improved pastures were infested with smutgrass and that the average | level of infestation was 38%. Smutgrass is considered to be the most common and most troublesome weed in pasture in Florida (Table 1). The objectives of this experiment were to determine the effects of grazing pressure and rest period, at five levels each, on the botanical composition of a smutgrass- bah i agrass-wh i te clover sward. Mob grazing techniques were used to carry out the perscribed grazing pressures ranging from 500 to 3700 kg/ha residue after grazing. The length of rest period between grazing ranged from 0 (continuous grazing) to 50 days of rest . Only one season of grazing has been completed, thus the results should be considered to be tentative. The preliminary results indicate that the length of rest has little effect on changes in botanical composition. However, the level of grazing pressure has -shown significant differences in botanical compo- sition following just one season of grazing. The smutgrass ground cover increased with time at the lower grazing pressures. In addition a slight decrease in smutgrass ground cover was observed at the highest grazing pressure and shorter rest periods. By October of the first season of grazing, white clover had become a significant part of the sward under heavy grazing pressures. By March, nearly 100% of the canopy cover of the heavy grazed pastures were clover, whereas almost no clover existed under the lightest grazing pressure treatments . It should be pointed out that considerable weight losses were experienced on catttle that were forced to consume nearly all of the smutgrass in a pasture. ACKNOWLEDGEMENTS The author would like to acknowledge the assistance of Mr. Leonidas Valle and Mr. A1 Schlundt in gathering the data on the experiment reported and Drs. W.L. Currey and D.H. Teem for supplying survey information on the weed problems in Florida pastures. 148 Table 1. The ten most common and most troublesome weeds in pasture in Florida* Most Common Most Troublesome Smut grass Smutgrass Dogfenne 1 Dogfenne 1 Wax myrtle Wax myrtle Vaseyg rass Sandbu r Curly dock Broomsedge Torpedograss Prickly pear Broomsedge Nutsedge Horseweed Torpedog rass Prickly pea r Curly dock Nutsedge Horseweed -From January 1977 Southern Weed Science Society Research Report. Tables 8 and 26. 149 WEED PROBLEMS IN ALABAMA PASTURES By C. S. Hoveland The major weed problems in pastures are listed in order of importance Warm Season Perennial Grasses 1. Dogfennel (Eupatorium capillifolium) 2. Smutgrass (Sporobolus poiretti) 3. Broomsedge (Andropogon virginicus) 4. Wolftail (Carex cherokensis) , Black Belt only. 5. Multiflora rose (Rosa multiflora) 6. Blessed thistle (Cnicus benedictus) 7. Horse nettle (Solanum carolinense) 8. Bitter sneezeweed (Helenium amarum) 9. Carolina geranium (Geranium carolinianum) 10. Henbit (Lamium amplexicaule) 11. Redroot pigweed (Amaranthus retrof lexus) , northern Ala. 12. Ragweed (Ambrosia artemisif olia) , northern Ala. Cool Season Perennial Grasses (Tall Fescue) 1. Broomsedge (Andropogon virginicus) Cool Season Annuals 1. Curly dock (Rumex cr ispus) 2. Wild mustard (Brassica kaber) 3. Redroot pigweed (Amaranthus retrof lexus) 4. Ragweed (Ambrosia artemisifolia) 5. Florida purslane (Richardia scabra) , southern Alabama 6. Cutleaf evening primrose (Oenothera laciniata) 7. Carolina geranium (Geranium carolinianum) 8. Goosegrass (Eleusine indica) , southern Alabama 150 MONENSIN - WHAT, HOW AND POTENTIAL ON PASTURE Gerald W. Horn Monensln is a monocarboxylic polyether antibiotic produced by Streptomyces cinnamonensis , and has been shown to exhibit moderate in vitro activity against gram-positive organisms and certain mycobacteria (Harvey and Hoehn, 1967). Monensin sodium is marketed as a feed additive (Rumensinl) for improved feed efficiency of "cattle being fed in confinement for slaughter". The approved feeding level of monensin for feedlot cattle is 5 to 30 g per ton of feed. Weight gains of feedlot cattle fed monensin may be unchanged, increased or decreased depending on the level at which monensin is fed (Raun et_ al_. , 1976). Studies relative to the effect of monensin on ruminal fermentation, performance of forage-fed cattle, feed efficiency of feedlot cattle, and carcass characteristics of cattle have been reported by Richardson et_ al . (1976), Potter et^ al. (1976), Raun et al . (1976), and Potter _et_ _al. (1976), respectively. The mechanism of action and potential of monensin for forage- fed cattle are discussed below. Mechanism of Action Although the mechanism of action of monensin is not completely understood, the improvement in feed efficiency of feedlot cattle is related to the shift that is effected by monensin in the production of ruminal volatile fatty acids (VFAs), increasing propionic acid and decreasing acetic and butyric acid concentrations (Richardson et al. , 1976). The shift in VFA production decreases ruminal fermentation energy losses by decreasing (1) methane production (Hungate, 1966) and (2) heat of ruminal fermentation (Wolin, 1960), and increases the amount of dietary energy available to the animal. Other actions of monensin may include: 1. Since greater quantities of ruminal propionic acid are produced in response to monensin, increased quantities should be available at the animal tissue level. Propionic acid may be utilized more efficiently by animal tissues than other VFAs due to a lower heat of metabolism (heat increment) and save energy. (Thornton and Owens, 1976) 2. Monensin may have a protein-sparing effect by (a) decreasing ruminal destruction of feed protein and/or amino acids by bacteria, and (b) decreasing the catabolism of gluconeogenic amino acids at the animal tissue level as a result of increased propionic acid. 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P. 00 •H •H cd rH a; co r. 3 o m B 3 cd 3 3 r 3 3 5-i 5-i 5-i 4-1 CO OO *H 3 3 3 3 3 3 Q- a -3 3 3 54 >H 3 3 O 4-J 4-J i — i 3 o 5-i r •H 3 a 4J a. 54 54 3 3 3 3 3 3 3 3 CO cd m3 >—1 6 O 3 m o 3 3 CD 3 3 3 3 > Oh m3 3 3 54 54 1 1 4-4 0) •H 1 o 3 3 3 £ 3 3 4-J CD 3 30 4-1 54 O 3 54 54 3 3 0J i — 1 4-1 CO -3 3 i — i )-i u 3 3 3 cd 3 3 rH 3 OO rH m CN 00 00 44 44 00 CO CD cd 3 oo m 5-4 3 a rH 3 3 5-i 54 54 3 3 3 O 1 — 1 3 3 3 3 CCJ 5-i u 5-4 3 -H 0) 00 r 4-1 CD no 54 00 00 00 Hi a m vO rH rH Oh 3 3 !-i CD CD Td m3 5-i -3 r — 1 m 3 3 4-J 54 2 3 3 o 3 >4 •H O m 44 44 44 44 CD CD 0) 5-4 3 -3 5-i •H 54 O E B B m3 o 3 Hi 3 3 3 3 6^5 EN? mi ^ 00 a; a 00 4-J O 2 5-4 54 54 3 3 Hi 5 3 3 3 3 cn .10) decrease in ruminal dry matter digestion (Amos et al. , 1976a) . The apparent CBG protein which reached the abomasum was 5-0, 13.5, 40.8 and 71.4 g/day for the 0, .5, 1-0 and 1.5% for- maldehyde treatments, respectively. These data were calculated by subtracting total microbial protein per treatment plus 12. 5g endogenous protein daily from total nonammonia CP and show that 4.4, 11.8, 36. 1 and 63.1% of the CBG protein appeared to reach the abomasum with increasing levels of formaldehyde. The following formula was used to estimate the maximum quantity of each respective amino acid which reached the abomasum from forage protein daily: Maximum Amino Acid _ Total of Respective (Microbial Protein Percent of ) from Forage Protein Amino Acid Recovered (Recovered in Respective ) at Abomasum (g/day) (Abomasum (g/day) Amino Acid in) ( 100 Microbial ) ( Protein ) Results from these calculations and the average intake of each amino acid are shown in Table 3. The total of each respective amino acid reaching the abo- masum daily may be found in Table 6 (see Amos et_ al . , 1976a). In addition, it should also be emphasized that the term "maximum amino acid from forage protein" is used here because the above formula does not correct for the con- tribution of endogenous protein secretions to the total of a respective amino acid. These data clearly show that treating CBG protein with formaldehyde increases the quantity of each amino acid from the forage protein due to its not being degraded in the rumen. For example, an average of 4.9g of lysine was fed daily for each treatment and approximately 1.6, 1.8, 3.2 and 4 . Og of this lysine reached the abomasum at the 0, .5, 1.0 and 1.5% formaldehyde treatment level, respectively. For the total essential amino acids, the data indicate that 11.9, 12.3, 24.2 and 28. 7g reached the abomasum daily and in- dicate that a maximum of 29. 4, 30.4, 59-9 and 71.0% of the essential amino acids consumed by the animal reached the abomasum at 0, .5, 1.0 and 1.5% formaldehyde treatment. Essentially the same results were noted with respect to the nonessential amino acids, 45. 7g were consumed and 13.6, l6.6, 27.4 and 30. 3g of nonessential amino acids were recovered from the abomasal digesta at 0, .5, 1.0 and 1.5% of formaldehyde, respectively. These latter data indicat- ed that a maximum of 29.8, 36.3, 60.0 and 66.3% of the nonessential amino 159 TABLE 3. — Maximum recovery of amino acids from coastal bermudagrass protein in the abomasal digesta (trial 1, g/day) . cl Ammo Acid Formaldehyde level ( % ) Intake .0 .5 1.0 1.5 Lysine 4-9 1.6 1.8 3.2 4.0 Histidine 1.9 • 7 .8 1.2 1.3 Arginine 4.6 1.1 1.6 2.7 3.3 Threonine 4.2 1.6 1.7 2.7 3.4 Valine 5.4 1.8 1.1 3.4 3.8 Isoleucine 4.4 1.5 1.8 2.9 3.3 Leucine 7.8 1.9 3.0 5-2 5.8 Phenylalanine 4.5 1.0 • 5 1.7 2.1 Methionine + Cystine 2.7 • 7 .7 1.2 1.7 Total Essential 40.4 11.9 12.3 24.2 28.7 Aspartic Acid 10.9 2.9 3.9 7.6 7.5 Serine 4.5 1.7 2.0 2.9 3.3 Glutamic Acid 10.6 2.7 3.7 6.5 7.2 Proline 4.9 1.5 1.9 2.4 3.2 Glycine 4.8 1.6 1.7 2.4 3.2 Alanine 6.7 2.3 2.4 3.8 4.1 Tyrosine 3.3 • 9 1.0 1.8 1.8 Total Nonessential 45.7 13.6 16.6 27.4 30.3 Total Essential + Nonessential 86.1 25.5 28.9 51.6 59-0 aThere was a highly significant linear : increase in each amino acid. total essential and total nonessential amino acids apparently derived from CBG protein with increasing formaldehyde level. 160 acids consumed reached the abomasum at the respective 0, .5, 1.0 and 1.5% formaldehyde treatment level. The effect of CBG maturity (quality) on the daily quantities of total CP, ammonia, nonammonia CP, microbial protein, apparent forage protein and amino acids from CBG protein was determined in trial 2. The high quality CBG (HQ- CBG) was 21 days of age, field chopped, drum dehydrated, ground and pelleted and contained 1 6.4% CP and 4.8% acid detergent lignin (ADL) on a dry matter basis. The low quality CBG (LQ-CBG) was 56 days of age, partially sun cured, belt dehydrated, ground and pelleted and contained 9-3% CP and 7.3% ADL on a dry matter basis. The wethers consumed 725g and 675g of the HQ-CBG and LQ- CBG per day, respectively. Table h presents a summary of the quantities of various abomasal CP com- ponents for the HQ- and LQ-CBG study. The wethers received 110.7 (HQ-CBG) and 58. 3g of CP (LQ-CBG) daily (as fed basis). Total crude protein reaching the abomasum was 125.8 (HQ-CBG) and 97. 2g (LQ-CBG) daily. When expressed as a percentage of intake, a higher percentage (P<.05) of the CP consumed reached the abomasum in wethers fed the LQ-CBG. This increase of approximately 39g CP (6. 2g nitrogen) between the diet and abomasum (LQ-CBG) is indicative of the ruminant's ability to consume and recycle nitrogen when placed on a diet marginal in CP. With respect to the HQ-CBG diet, the wethers recycled approxi- mately 15g of CP (2.4g nitrogen) through the rumen daily. These results, con- trasted to trail 1, show the effect of artificial heat on CBG during the dry- ing process. In trial 1, there was a loss of nitrogen (l.79g/day) between the diet and the abomasum in wethers fed sun cured hay. Also in trial 1, only about b.b% of the CBG protein reached the abomasum (Table l) , while in trial 2,48.3g (43.6%) of the CP in the HQ-CBG diet reached the abomasum. The effect of CBG maturity on the passage of CBG protein is quite notice- able (Table 4). These data show that 48. 3g and 36. 3g of the forage protein reached the abomasum daily and accounted for 43.6 and 62.3% of the forage protein consumed for the HQ-CBG and LQ-CBG, respectively. Nonammonia CP\ and ammonia were higher in the abomasal digesta in wethers fed the HQ-CBG and re- sulted from both increased CP intake as well as the increased synthesis of microbial protein with this diet. Microbial protein reaching the abomasum daily was higher on the HQ-CBG (38. 8g) compared to the LQ-CBG (30. 8g). Table 5 gives the daily intakes and quantities of amino acids reaching the abomasum (trial 2). In wethers fed the HQ-CBG, the quantity of only the sulfur containing amino acids (methionine and cystine) were increased by rumen fermentation (P<.0l). In wethers fed the LQ-CBG diet, the quantities of all individual essential amino acids (except arginine) and total essential amino acids were increased during passage of the diet to the abomasum (P<.0l). The quantity of arginine increased between the diet and abomasum (P<.05). Total essential amino acids reaching the abomasum were increased approximately 2.3 times between the diet and the abomasum of wethers fed the LQ-CBG diet. In wethers fed the HQ-CBG diet, total nonessential and individual non- essential amino acids (except serine and tyrosine) (Table 5) tended to de- crease during passage of the diet to the abomasum. With respect to the LQ- CBG diet, there was a highly significant increase in individual and total nonessential amino acids, except proline, during passage of the diet through the ruminoreticulum to the abomasum . The data in Tables 4 and 5 indicate less destruction of the dietary amino acids from CBG protein of advanced age and more destruction and resynthesis of amino acids when diets composed of more immature CBG are fed. However, care must be exercised in making an overall 161 TABLE h. — Intake and. recovery of total protein, microbial protein and apparent forage protein from the abomasal digesta of wethers fed high and low quality coastal bermudagrassa (trial 2) Crude Protein Component High Quality Low Quality (g/day ) Intake 110.7 58.3 Abomasal digesta 125.8 97.2 Percent of intake 113. 6b 166.7° As ammonia 26.2 17.6 Honammonia 99-6 79.6 Microbial 38.8 30.8 Apparent forage U8.3 36.3 Si Adapted from the data of Amos, et al. , 1976b. J. Anim. Sci. U2:970. b , c Means on the same different (P<.05) line with different superscripts are ^Calculated by subtracting microbial protein + endogenous protein (I2.5g/day) from nonammonia, crude protein. 162 Table 5- — Intake and recovery of amino acids from coastal bermudagrass protein in the abomasal digestaa (trial 2) Amino Acid High Quality Low Quality Diet Abomasum Diet Abomasum ( g/ da> ) Lysine 4.6 5.7 2.0b 5 • 2C Histidine 1.8 1.8 .4b 1.6° Arginine 4.4 4.0 l. 8d 3.1e Threonine 3.9 4.6 1.7b 4 . lc Valine 5.0 5.1 2.1b 4 . 5C Isoleucine 4.1 5.0 1.7b 3 . 8C Leucine 7.3 7.9 2.9b 6.3° Phenylalanine 4.2 4.7 1.6b 3 . 6C Methionine + Cystine 2.0b 3.3° • 9b 3 • 2C TOTAL 37.3 42.1 15. lb 35.4c Aspartic acid 10.2 8.4 5. lb 7 . 8C Serine 4.2 4.2 1. 8b 3.7° Glutamic acid 10.0 8.6 4 . 2b 8.2° Proline 4.6 4.3 3.2 4.2 Glycine 4.5 4.7 2 . 2b 3.9C Alanine 6.2 6.0 2. 5b 5 • 0C Tyrosine 3.1 3.7 2 . lb 3 • 6C TOTAL 42.8 39-9 21. lb 36.4c GRAND TOTAL 80. 1 82.0 46. 2b 71. 8C aAdapted from the data of Amos, et al., 1976b. J. Anim, . Sci. 42:970. ,CMeans on the same line within treatment with unlike superscripts differ significantly (P<.01) . u , e Means on the same line within treatment with unline superscripts differ significantly (P< .Op) . 163 interpretation of the amino acid availability from the quantities reaching the abomasum in wethers fed the LQ-CBG diet. Sniffen and Jacobson (1975) have shown that quantites of amino acids absorbed from the intestines of steers fed an immature alfalfa hay diet was 5-3 times the quantity absorbed in steers fed a lower quality more mature diet. Thus the actual availability of amino acids from the forage protein escaping rumen degradation may have differed greatly in the study reported here. SUMMARY The stability of CBG protein to rumen microbial degradation was studied by using mature wethers as assay animals. Only 4.4% of CBG protein reached the abomasum in wethers fed a good quality CBG hay. However, forage protein reaching the abomasum increased to 11.8, 36.1 and 63-1% when the hay was treated with .5, 1.0 and 1.5 % formaldehyde, respectively. Treating CBG with formaldehyde or artificially dehydrating the forage reduced nitrogen (CP) loss during passage of the diet to the abomasum. Amino acids reaching the abomasum were increased over two fold by rumen fermentation of a LQ-CBG diet; however, only methionine and cystine were increased by rumen fermentation of a high quality CBG diet. LITERATURE CITED Akeson, W. R. and M. S. 'Stahman. 1965- Nutritive value of leaf protein concentrate, an in vitro digestion study. J. Agr. Food Chem. 13:415. Amos, H. E., J. Evans, D. Burdick and T. Park. 1976a. Nitrogen balance and abomasal crude protein and amino acids in wethers fed formaldehyde treated Coastal bermudagrass . J. Anim. Sci. 43:1300. , J. Evans and D. Burdick. 1976b. Abomasal protein recovery and microbial protein synthesis in wethers fed high and low quality forage diets. J. Anim. Sci. 42:970. Hogan, J. P., R. H. Weston and J. R. Lindsay. 1970. The effects of rumi- nal digestion of forages on the quantities of amino acids supplied to sheep. In M. J. T. Norman (Ed.) Proceedings of the XI International Grassland Conference. Queensland, St. Lucia, Queensland. , A. T. Phillipson. i960. The rate of flow of digesta and their removal along the digestive tract of sheep. Brit. J. Nutr. l4 : 147. Sniffen, C. J. and Don R. Jacobson. 1975- Net amino acid absorption in steers fed alfalfa hay cut at two stages of maturity. J. Dairy Sci. 58:371. Woodham, A. A. 1971. The use of animal tests for evaluation of leaf pro- tein concentrates. In N. W. Pirie (Ed.) Leaf Protein: Its. Agronomy, Preparation and Use. Burgess and Son, Abingdon, Berks England. 164 WEED PROBLEMS IN TEXAS PASTURES By Gerald W. Evers TAME PASTURES Herbicides used on established pastures are 2,4-D, dicamba, simazine and atrazine with 2,4-D being used most widely. Simazine is also used in es- tablishing bermudagrasses . Establishment of warm season perennial grasses is difficult, especially in high rainfall areas, due to weed competition. Para- quat, a fast acting contact herbicide, is being evaluated at Angleton for es- tablishing dallisgrass (Paspalum dilatatum Poir.) and bahiagrass (Paspalum notatum Flugge) . Grasses are planted and then paraquat is applied after the weeds come up but before the desired grasses emerge. Smutgrass (Sporobolus indicus (L.) R. Br.), the major weed in improved pastures in Southeast Texas, is now being controlled with dalapon. Dalapon applied in the fall for smutgrass control also permits sod seeding of ryegrass for winter pasture. Herbicides are being evaluated for irrigated alfalfa in West Texas. Most of the alfalfa is marketed as cubes, but when the forage contains more than 10% weeds, the cubes will not hold together. RANGE Herbicides used for brush control in South and West Texas are 2,4,5-T and picloram or a mixture of the two. However none provide good control of mes- quite (Prosopis spp.) the major brush problem in Texas. Tebuthiuron which is to be available soon, controls broadleaf weeds and some brush species includ- ing Western Honey Mesquite (Prosopis glandulosa var. torreyana (Benson) M. C. Johnston). Dicamba and 2,4-D are used to a limited extent on rangeland. Use of herbicides on Texas pastures and rangeland would increase with an increase in cattle prices. ACKNOWLEDGEMENTS I would like to thank the following Area Agronomists for providing infor- mation for this report: George Alston, Albert Colburn, Richard Hoverson, Kenneth Lindsey, Dale Lovelace, and Ken Smith and Extension Weed Specialist Rubert Palmer. 165 QUALITY OF LEGUME INOCULANTS AND HOW IT AFFECTS CLOVER PRODUCTION IN THE SOUTH !' By Kenneth L. Smith The symbiotic relationship between rhizobia and legumes has been known for nearly a century and many scientific advancements have been made since that time. We have discovered that different clovers require different strains of rhizobia bacteria to produce maximum nodulation. We have found that other bacteria compete with effective rhizobia for nodulation sites on the roots of legumes. We have found that soil temperature as well as storage temperature of the inoculant has an effect on how well legumes become inoculated and produce. We have learned that excessive CO^ in the root environment can inhibit inoculation. We have learned that Ca, B, S, Mo, Fe, Cu and Co are needed for the nitrogen-fixing process as well as ample amounts of P and K for plant growth. We have learned that a soil with a pH of greater than 6.0 is better for rhizobia than soils with lower pH values. Yet, with all these scientific advancements, producers in the South are still having difficulty getting clovers properly established due to poor inoculation. The objective of inoculation is to insure effective nodulation of the legume by providing adequate numbers of effective rhizobia at planting time and effective nodulation is considered achieved when the legume fixes enough nitrogen to meet its nutritional requirements during all stages of plant growth. It would be desirable to have a legume that was capable of fixing enough nitrogen to supply not only its own needs, but also the nitrogen requirement of a grass growing in a mixture with it. One day, our plant breeders and microbiologists will likely develop just such a plant. The problem at present is to develop better methods of growing existing species. There have been conflicting data concerning the number of rhizobia required per seed in order to achieve effective nodulation. The numbers required will vary between species and environments. Date (2) reported that 100 rhizobia per clover seed were adequate under ideal conditions; however, Holland (_3) concluded subclover should be inoculated with 7.5 x 10^ rhizobia for effective nodulation in field conditions. Weaver used number of nodules on the tap root of soybeans as a measure of effective nodulation (7J and concluded that uninoculated soybeans planted in soil with less than 103 rhizobia per gram resulted in poor nodulation (8). The Australians have a legume program that is far superior to the legume program in the United States, especially in the Southern United States. Much of this success can be attributed to their superior knowledge and appreciation of rhizobia. Australian farmers normally plant 103 rhizobia per seed and, if numbers are less than 300, the inoculum is considered unsatisfactory for sale. 166 One of the most complex and extensive educational efforts lies ahead if the Southern United States is to truly develop a legume system that works. Producers must be taught the importance of effective nodulation and how to determine if their legumes are effectively nodulated. There is a difference in methods of inoculation as indicated by the number of nodules found on the tap and lateral roots of Louisiana S-l clover (Table 1) (6_) . There is a positive correlation between numbers of nodules on the tap root and the dry matter production (Table 2) (6); however, such a correlation may not exist for protein content of clovers TTable 3) (6_) . Most of the response to the inoculation methods can be attributed to rhizobia numbers and probably little to any superior ingredients of the inocu- lant preparation. Number of rhizobia per seed increases drastically due to better sticking agents (Table 4) (6_) . Calcium carbonate pelleting offers some potential for increasing rhizobia numbers and clover performance (Table 5) (5j ; however, pelleting on the farm is laborious and discourages many farmers from planting clovers. The fact that seed planted in fumigated soil and inoculated at normal rates gave similar .[yields to CaC03~pel 1 eted seed suggests that competitiveness and antagonistic organisms are causing some real problems. Some seed companies have elected to pre-inoculate seed as a convenience to the farmer and, hopefully, increase clover performance and seed sales. Not all pre-inoculated seed are of good quality as reported by Purdue University (Table 6) (4). Most clovers are fall planted in the Southern United States which means shipping seed and inoculant during the hot summer days in order to reach distributors in time for planting. This creates a problem that will not be overcome without a great deal of effort and understanding from everyone involved. The extent of damage to rhizobia by heat is exemplified in Table 7 a). This paper is presented in an attempt to point out some of the problems facing legume production in the South as they are related to inoculation. Hopefully, it will stimulate thinking among those concerned which will lead to better inoculation procedures with high quality products to enable the Southern United States to develop a reliable legume program. REFERENCES 1. Burton, J. C. Unpublished data. 2. Date, R. A. 1968. Rhizobial survival on the inoculated legume seed. 9th Int. Congr. Soil Sci . Trans. 11:75-84. 3. Holland, A. 1970. Competition between soil and seed-borne Rhi zobi urn trifolii in nodulation of introduced Tri folium subterranium. Plant Soil 32:293-302. 4. Purdue University. 1975. Inspection Report 106. 5. Wade, R. H. , C. S. Hoveland and A. E. Hiltbald. 1972. Inoculum rate and pelleting of Arrowleaf clover seed. Agron. J. 64:481-483. 6. Waggoner, B. S. 1976. Nitrogen fixation by clover in Southeast Texas. Master's Thesis, Texas A&M University. 167 7. Weaver, R. W. and L. R. Frederick. 1972. Effect of inoculum size on nodulation of Glycine max L. Merrill, variety Ford. Aqron. J. 64:597-599. 8. Weaver, R. W. and L. R. Frederick. 1974. Effect of inoculum rate on competitive nodulation of Glycine max L. Merrill. I. Greenhouse studies. Agron. J. 66:229-232. TABLE 1.- -Inoculation methods of Louisiana S-l clover Treatment Planted 11/15 3/10 T L Sampling Date 4/1 T L 4/17 T L 0-1 1 5 2 4 5 34 P+W 1 8 2 12 9 46 P+GA 11 16 12 23 19 46 P+P 11 14 12 34 15 36 TABLE 2. --Dry matter production-Louisiana S-l Treatment Date 3/10 4/1 4/17 g/ 30 cm row kg/ha 0-1 9.7 14 1593 P+W 5.9 13 1361 P+GA 10.9 29 2312 P+P 11 .1 25 2582 TABLE 3. --Protein content-Loui si ana S-l Treatment 3/10 Date 4/17 6/5 0-1 10.1 18.3 20.3 P+W 11.2 16.4 18.1 P+GA 18.7 21 .2 18.9 P+P 20.0 20.2 19.0 168 TABLE 4. — Estimated number rhi zobi a/seed at planting Treatment La. S-l Arrowleaf Peat 600 25 Pel i noc 3 ,000 3,000 TABLE 5. — Inoculation methods-Arrowl eaf Dry Matter-kg/ha Total 3/11 5/11 CaCO^ Pellet 980 7490 Soil Fumigation 584 7380 1 x Inoc. 330 4630 3 x Inoc. 760 6900 0 Inoc. 90 5260 TABLE 6. --Pre-i nocul ated seed Good Fai r Unsati sf actory Number 42 14 30 Percent 49 16 35 TABLE 7. --Million bacteria in peat Week 45°F 72°F 90°F 1 06°F 0 794.4 794.4 794.4 794.4 2 794.4 794.4 199.5 28.8 4 794.4 562.4 56.2 56.6 6 794.4 316.3 44.7 4.5 8 794.4 125.9 31.6 3.2 169 SPFCIC EXTENSION WORK GROUP SUMMARY OF FIVE MINUTE REPORTS BY STATES SUBJECT: Status of Cool Season Grasses by Donald M. Ball, Extension Agronomist, Auburn University The Extension Work Group of the SPFCIC involved itself this year with a discussion of cool season grass species. This discussion centered around five-minute reports presented by representatives from the states which partici- pate in the SPFCIC. Points discussed regarding each species mentioned in- cluded: (1) acreage; (2) grazing season; (3) varieties; (A) primary usage; and (5) rates of liming and fertilization. As far as cool-season perennials are concerned, tall fescue is the pre- dominant species used in the south. Most of the 'fescue acreage is in the more northerly states in the region, however. Florida is the only state having essentially no tall fescue acreage. The predominant tall fescue variety is "Kentucky 31", although some states (particularly the more northerly ones) also reported some acreage of "Alta", "Goar", "Fawn", and "Kenwell". In most states over 90% of the tall fescue acreage is devoted to providing grazing for beef cattle. It is also, however, utilized to some extent for providing grazing for dairy animals, and in some states to a very limited extent by swine, sheep, and horses. It was reported that in many instances tall fescue is used primarily for grazing, but with surplus growth being cut for hay. Most fescue hay produced is fed to beef animals. It was mentioned that while spring and fall grazing of fescue is reasonably good, summer quality declines badly - particularly in the more southern states. Orchardgrass is the second most popular cool-season perennial grass spe- cies in the southern region. As with tall fescue, the largest acreage is in the northern part of the region. Most states have less than one-fourth as much acreage of orchardgrass as tall fescue which has a slightly longer grow- ing season and somewhat higher production. The primary varieties grown are "Boone", "Potomac", and "Hallmark." There is also considerable acreage common orchardgrass grown in the region. Because of the relatively good quality of orchardgrass, a much higher percent of the acreage is used for diary animals, horses, sheep, and swine than is the case with tall fescue. In some of the more northern states, only one-fourth of the acreage or less is used to provide feed for beef animals. It was mentioned that persistence is a problem with growing orchardgrass in the more southern states, and several southern states reported essentially no acreage of orchardgrass. 170 There is a very small acreage of other cool-season perennial grass species in the southern region. Smooth bromegrass, wheatgrass, and hardinggrass are grown to a small extent in Texas and nearby states. Also, Kentucky bluegrass and timothy are used to some extent in the more northern states, but these are generally of minor interest to producers in most states in the south. As far as cool-season annual grasses are concerned, ryegrass is the most widely adapted species in the southern region. The area of greatest usage of ryegrass is in the central and lower south. "Gulf, "Tetrablend 444" and "Magnolia" were reported as being the most commonly- grown varieties. In the southern region as a whole, probably around 80% or more of the ryegrass acre- age is used to provide grazing for beef animals, although it also provides excellent grazing for dairy cows and other farm animals. Ryegrass is used to a small extent for hay, silage, or greenchop, and is frequently grown in com- bination with small grains and/or annual clovers - particularly when used in stocker calf programs. The practice of overseeding warm-season perennial pastures with ryegrass appears to be increasing in popularity in the lower south . The small grains (rye, wheat, barley, and oats) are used extensively for forage throughout the southern region, but the extent of use of a given spe- cies varies according to area. Barley is most suited to be grown in the more northern parts of the region, with "Barsoy", "Keowee", "Volbar", and "Clayton" being some of the varieties most frequently used. The wheat acre- age also tends to be concentrated in the upper part of the region, with "Arthur", "Abe", "Wakeland", and "Coker 68-15" being popular varieties. Rye is quite popular in the central and lower south, with "Wren's Abruzzi", McNair Vita Graze" , "Wintergrazer" , and "Florida Black" being widely grown varieties. Oats, which are the least winterhardy of the small grains, are grown mostly in the lower south. "Florida 501", "Coker 227", and "Elan" are some of the most widely grown oat varieties. It was generally agreed that one of the primary problems involved in the production of cool-season grasses in the southern region is inadequate ferti- lization and liming. Representatives of most states indicated that, on the average, cool-season grass acreage received one-third or less of the recom- mended annual application of fertilizer and lime. 171 CONTRIBUTORS [w Ahring, R. M. Research agronomist, Agricultural Research Service, Department of Agronomy, Oklahoma State University, Stillwater, OK 74074 Akin, Danny E. Microbiologist, Richard B. Russell Agricultural Research Center, Agricultural Research Service, P.0. Box 5677, Athens, GA 30604 Amos, H. E. Research physiologist, Richard B. Russell Agricultural Research Center, Agricultural Research Service, P.0. Box 5677, Athens, GA 30604 Bal 1 , Donald M. Extension agronomist. Department of Agronomy, 105 Extension Hall, Auburn University, Auburn, AL 36830 Barnes, R. F. Staff scientist, forage and range. Agricultural Research Service, National Program Staff, Room 411, Bldg. 005, Beltsville Agricultural Research Center, Beltsville, MD 20705 Barnett, 0. W. Asst, professor of forage legume pathology. Department of Plant Pathology and Physiology, Clemson University, Clemson, SC 29631 Burdick, Donald Research chemist, Richard B. Russell Agricultural Research Center, Agricultural Research Service, P.0. Box 5677, Athens, GA 30604 Busbice, Thad H. Professor, Crop Science Department, North Carolina State University, 1126 Williams Hall, Raleigh, NC 27607 Burson, B. L. Research geneticist, Agricultural Research Service, P.0. Box 748, Temple, :K ill hi 'S' ■; .a TX 76501 Burton, Glenn W. Research geneticist, Agricultural Research Service, Department of Agronomy, Georgia Coastal Plain Experiment Station, Tifton, GA 31794 Carpenter, John C., Jr. Superintendent, West Louisiana Experiment Station, P.0. Box 26, Rosepine, LA 70659 h Ciordia, H. Parasitologist, Cattle Parasites Research Laboratory, Agricultural Research Service, Experiment, GA 30212 j | Donnelly, E. D. Professor of agronomy and soils, Auburn University, Auburn, AL 36830 Elkins, Charles B. j h Soil scientist, soil and water research. Agricultural Research Service, 230 Funchess Hall, Auburn University, Auburn, AL 36830 Engelke, M. C. | Research geneticist, Agricultural Research Service, P.0. Box 748, Temple, TX- 76501 Essig, H. W. h Professor of ruminant nutrition. Animal Science Department, P.0. Drawer 5228, Mississippi State University, Mississippi State, MS 39762 Evans, J. J. I Research physiologist, Richard B. Russell Agricultural Research Center, Agricultural Research Service, P.0. Box 5677, Athens, GA 30604 172 Evans, J. Kenneth Extension specialist, soils, Department of Agronomy, University of Kentucky, Lexington, KY 40506 Evers, Gerald W. Asst, professor of forage physiology, Texas Agricultural Experiment Station, P.0. Box 728, Angleton, TX 77515 Gibson, P. B. 'Research agronomist, clover breeding and genetics. Department of Agronomy and Soils, Agricultural Research Service, Clemson University, Clemson, SC 29631 Haaland, R. L. Asst, professor of agronomy and soils. Department of Agronomy, Auburn University, Auburn, AL 36830 Harris, R. R. Professor of ruminant nutrition, 112 Animal Science Bldg., Department of Animal and Dairy Sciences, Auburn University, Auburn, AL 36830 Horn, Gerald W. Assoc, professor. Animal Science Department, Oklahoma State University, Stillwater, OK 74074 Hoveland, C. S. Professor, Department of Animal and Dairy Sciences, Auburn University, Auburn, AL 36830 Johnson, Wiley Professor of plant breeding, 237 Funchess Hall, Department of Agronomy and Soils, Auburn University, Auburn, AL 36830 Jorgensen, N. Professor of dairy sciences, Department of Dairy Science, University of Wisconsin, Madison, WI 53706 Langford, W. R. Agronomist, Regional Plant Introduction Station, Agricultural Research Service, Experiment, GA 30212 McCaskey, T. A. Assoc, professor of food mi crobiol ogy , Department of Animal and Dairy Sciences, Auburn University Agricultural Experiment Station, Auburn, AL 36830 Moore, John E. Assoc, professor of animal science, Nutrition Laboratory, Department of Animal Science, University of Florida, Gainesville, FL 32611 Ocumpaugh, W. R. Asst, professor. Department of Agronomy, 2183 McCarty Hall, University of Florida, Gainesville, FL 32603 Palmertree, Hiram D. Extension agronomist, agronomy, forage, pasture, and turf. Department of Agronomy, Mississippi State University, Mississippi State, MS 39762 Quesenberry, K. H. Assoc, professor, Agronomy Department, University of Florida, Gainesville, FL 32603 Ray, Maurice L. Professor of animal science. Department of Animal Science, University of Arkansas, Fayetteville, AR 72701 Richardson, W. L. Asst, professor. Department of Agronomy, Oklahoma State University, 173 Stillwater, OK 74074 Robinson, E. L. Research physiologist, Richard B. Russell Agricultural Research Center, Agricultural Research Service, P.0. Box 5677, Athens, GA 30604 Rodri guez-Kabana , R. Alumni professor of botany and microbiology, Auburn University, Auburn, AL 36830 Rohweder, D. A. Professor of agronomy and dairy science. Department of Agronomy, University of Wisconsin, Madison, WI 53706 Schank, S. C. Professor of agronomy. Department of Agronomy, 2183 McCarty Hall, University of Florida, Gainesivlle, FL 32603 Shenk, J. S. { Assoc, professor of plant breeding, Department of Agronomy, Pennsylvania State University, University Park, PA 16802 Smith, Kenneth L. Area agronomist, Texas A&M University, P.0. Box 220, Overton, TX 75684 Smith, Rex. L. Assoc, professor. Department of Agronomy, University of Florida, Gainesville, FL 32603 Spooner, A. E. Professor of agronomy. Department of Agronomy, University of Arkansas, Fayetteville, AR 72701 Taliaferro, C. M. Professor of agronomy. Department of Agronomy, Oklahoma State University, Stillwater, OK 74074 j Voigt, Paul W. Research geneticist. Agricultural Research Service, P.0. Box 748, Temple, TX 76501 j Watson, Vance H. Assoc, agronomist, pasture and forage crops. Department of Agronomy, Mississippi State University, Mississippi State, MS 39762 Wiggins, Agee M. Professor of veterinary medicine. Department of Large Animal Surgery and Medicine, Auburn University, Auburn, AL 36830 Wise, M. B. Head, Animal Science Department, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 *1977-GPO-1750-S/771-040/25; 174 U.S. DEPARTMENT OF AGRICULTURE AGRICULTURAL RESEARCH SERVICE SOUTHERN REGION P. O. BOX 53326 NEW ORLEANS, LOUISIANA 70153 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, S300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE AGR 101 US-MAIL