Proceedings of the Southern Pasture and Forage Crop Improvement Conference

Historic, Archive Document

Do not assume content reflects current
scientific knowledge, policies, or practices.

United States
Department of
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Proceedings
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39th Southern Pasture
and Forage Crop
Improvement Conference

May 23-26, 1983
Oklahoma City, Oklahoma

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ISSN 0193-6425

Proceedings

of the

39th Southern Pasture and Forage Crop
Improvement Conference

May 23-26, 1983
Oklahoma City, Oklahoma

Sponsored by

the Agricultural Experiment Stations of Alabama, Arkansas,
Florida, Georgia, Kentucky, Louisiana, Mississippi. North
Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee,
Texas, and Virginia

and the

Agricultural Research Service
U.S. Department of Agriculture

Agricultural Research Service
U.S. Department of Agriculture
1983

This publication is available from John D. Miller, Forage and
Turf Research Unit, Agricultural Research Service, Georgia
Coastal Plain Experiment Station, Tifton, Ga. 31793.

Proceedings of the Southern Pasture and Forage Crop Improvement
Conference, 39th, May 23-26, 1983, Oklahoma City, Oklahoma.
Issued October 1983.

Published by Agricultural Research Service (Southern Region) ,
U.S. Department of Agriculture, P.0. Box 53326, New Orleans,

La. 70153, from camera-ready copy supplied by the authors, who
accept responsibility for any errors in their papers. The
opinions expressed by the authors are not necessarily those of
the U.S. Department of Agriculture. Mention of pesticides does
not constitute a recommendation for use by USDA, nor does it
imply that the pesticides are registered under the Federal
Insecticide, Fungicide, and Rodenticide Act as amended. The
use of trade names does not constitute a guarantee, warranty,
or endorsement of the products by USDA.

ii

CONTENTS

The Forage-Livestock Industry in Oklahoma
Oklahoma’s livestock industry

Robert Totusek 1

Pasture-livestock management systems

W. E. McMurphy 8

Forage resources of Oklahoma

P. W. Santelmann 11

Forage breeding programs at the Oklahoma State
University

C. M. Taliaferro and J. L. Caddel 21

Range research at the Southern Plains Range Research

Station

P. L. Sims 26

Forage Plant Resources

Buffelgrass germplasm research for the southern Great
Plains

E. C. Bashaw and C. W. Johns 31

New sources of genetic variability in dallisgrass and
other Paspalum species

Byron L. Burson, Paul W. Voigt, and Wayne R. Johnson 35
Clover and special purpose legume germplasm resources
for the future

Gary A. Pederson and William E. Knight 42

Forage attributes for improved animal performance

H. Lippke 56

Panel Discussion: Data Required Before Releasing Forages.

What Kind and How Much?

The need for animal trials

D. A. Sleper, F. A. Martz , A. G. Matches, and J. R.

Forwood 61

USDA's practice at Tifton, Ga.

Glenn W. Burton and Warren G. Monson 67

Forage quality assessment: Important factors for plant
breeders to consider

S. W. Coleman 71

Grazing management and utilization research prior to
release of pasture cultivars

Carl S. Hoveland 85

State agricultural experiment station policies

W. C. Godley 89

iii

Page

Composition and ruminal availability of sulfur in cool-
season grasses

B. P. Glenn and D. G. Ely 93

Kochia — forage or weed?

L. M. Rommann 96

No-till forage establishment

Harlan E. White 98

Techniques using electronic communications

Clement E. Ward 102

Computerized hay marketing

Gerrit W. Cuperus 106

Effect of fertilizer application and grazing management on
grazed New Zealand hill country

M. Greg Lambert and David A. Clark 108

Recent progress in forage production and utilization in

Scotland

Thomas David Alexander Forbes 115

Contributors 125

IV

The Forage-Livestock Industry in Oklahoma

OKLAHOMA'S LIVESTOCK INDUSTRY

Robert Totusek

Oklahoma State University

INTRODUCTION

Oklahoma is livestock country, with two-thirds of the total farm
income in the state resulting from livestock. It has not
always been so. Fifty years ago, only one-third of the state's
farm income was attributed to livestock. During the last half-
century there has been a gradual shift from the production of
cash crops to the production of forage to support the major
portion of the state's livestock industry. Today, three-
fourths of the state's 44 million acres are utilized to a great
er or lesser degree by grazing animals.

Although Oklahoma's livestock industry is predominantly a graz-
ing livestock industry, the non-grazing types will also be men-
tioned briefly because they do impact directly or indirectly on
the total animal industry in the state.

SWINE

The swine industry in Oklahoma was at one time much larger than
today. In 1945 the state swine population totaled 1.2 million,
compared to 400 thousand today. The nature of the swine indus-
try has also changed, shifting from a family-farm type of pro-
duction with several sows on each farm, to large, highly spe-
cialized operations with several hundred sows each, in confine-
ment or semi-confinement. There is great potential for increas
ed swine production in the state. Oklahoma is a pork deficit
state, producing only about one-half of its needs and has sev-
eral inherent assets such as a mild climate. Consequently, it
has been projected that hog numbers in Oklahoma could increase
as much as 50% by 1990 and perhaps double by the end of the
century.

POULTRY

Many people are surprised to learn that poultry production

1

ranks 5th in Oklahoma among all agricultural commodities, rank-
ing only behind beef cattle, wheat, dairy cattle and hay. Per-
haps one reason is that the poultry industry in Oklahoma is al-
most totally located in the eastern tier of counties and is not
apparent to the casual traveler in many parts of the state. The
poultry industry in Oklahoma is primarily one of broiler produc-
tion; the number of broilers produced in the state increased
from 3 million in 1969 to 36 million in 1980.

The nature of the poultry industry has also changed drastically,
from one of farm- flock production with some poultry on every
farm, to a highly integrated, highly automated industry with
relatively few but very large producers.

It has been estimated that by 1990 per capita production of
poultry will exceed that of beef, with a demand for 44% more
broilers and 34% more layers. Consequently, it is likely that
Oklahoma’s poultry industry will continue to increase.

HORSES

Oklahoma is horse country! Although not considered food pro-
ducing animals in the culture of the United States, the many
horses in Oklahoma do compete vigorously for available forage
and must be considered relative to forage usage.

Changes in horse numbers in Oklahoma have been similar to those
of the United States. The national horse herd peaked at 20
million in 1920, decreased to 3 million in 1960, and is expect-
ed to reach 20 million again by 1985. There are likely about
500 thousand horses in Oklahoma, with more horses per square
mile than in any state in the country.

In 1920 and before horses were used primarily for work and
transportation, and only somewhat incidentally for pleasure;
today about 97% of the horses are used for pleasure. Although
many horses do serve an important role on working cattle ranches
in Oklahoma, the majority are used for rodeoing, trail riding,
exhibition, youth projects and simply for pleasure riding and
as companion animals.

The horse industry in Oklahoma is big business! It has been
estimated that each horse generates $1,000 in business for the
general economy, which means that in Oklahoma the horse indus-
try is a $500 million business. Now, with the advent of para-
mutual racing, it is anticipated that the state's horse popula-
tion will increase further, with a projected increase to 600
thousand by the end of the century if not much sooner.

SHEEP

Sheep numbers in Oklahoma have followed the same pattern as
national and even world numbers, with a decrease from 268 thou-

2

sand in 1940 to 72 thousand in 1977. Since the low point was
reached, there has been a gradual increase to 105 thousand in.
1982. Because sheep are very complementary to wheat production,
more than one-half of the total sheep in Oklahoma are found in
the major wheat producing area of north-central Oklahoma. How-
ever, they can be produced very satisfactorily throughout the
state.

Sheep offer some important advantages. They produce a choice
product without grain, produce both food and wool, facilitate
optimum range and pasture utilization when grazed with cattle,
are adapted to small farms, and perhaps most important have
tended to return a profit even in those years when beef cattle
production has been unprofitable. However, there are some
serious constraints to the expansion of sheep numbers. There
is a general lack of knowledge about sheep, and some general
sociological constraints in the minds of many people who prefer
to produce cattle. Although predators and parasites present
fewer problems than in the past, sheep are seasonal breeders,
and there is the perennial "vicious circle" of low numbers and
low consumption, with the low consumption caused not only by
low numbers, but also the high price of lamb. At the present
rate of increase, sheep numbers could double in Oklahoma by
1990 and more than quadruple by the end of the century. How-
ever, the constraints mentioned above will likely dampen the
projected increase in sheep numbers, especially if beef cattle
production is at all profitable.

DAIRY CATTLE

Dairy cattle rank as the third most important commodity in
Oklahoma agriculture, in spite of the fact that the dairy cow
numbers have decreased by 50% during the past 20 years. How-
ever, as is true nationally, the great increase in production
per cow has allowed the maintenance of a stable milk supply
with a considerably lower dairy cow population. In addition,
dairy production units have become much larger and more spe-
cialized; the average milk produced per farm in Oklahoma
doubled from 560 thousand in 1960 to 1.2 million pounds in 1980.

The very high level of milk production per cow found in some
herds today is a vivid testimony to the development and appli-
cation of technology, particularly in the areas of nutrition,
progeny testing and artificial insemination.

A need for 35-40% more milk has been projected by the
2000. In that event, recognizing Oklahoma’s inherent
tages of a relatively mild climate and a geographical
close to the sunbelt areas of high population growth,
cattle industry will increase in Oklahoma.

year
advan-
location
the dairy

3

BEEF CATTLE

Oklahoma is obviously beef cattle country, a situation which
has developed over the past 60 years:

CASH RECEIPTS FROM
YEAR CATTLE & CALVES, %

1929

14

1949

25

1963

41

1980

56

More specifically, Oklahoma is beef cow country. Again, the in-
crease over the past 60 years has been very dramatic, from 200
thousand cows in 1920 to 2.3 million in 1980. Today, there are
more beef cows per square mile in Oklahoma than in any state.
There is also a significant cattle feeding industry in Oklahoma,
largely centered in the Panhandle, where almost 600 thousand
head are fed each year.

The nature as well as the size of the beef cattle industry in
Oklahoma has changed markedly in the past 100 years, from the
time of the Longhorn cattle (in some respects we have come
"full circle" because today Longhorn bulls are being frequently
used on first-calf heifers to minimize calving problems) . Un-
til about 1950 commercial beef cattle production in Oklahoma
consisted largely of straight-bred British breeds which had
been bred up from the original Longhorn base. However, as
knowledge developed about the benefits of heterosis, producers
began crossbreeding and today the majority of calves coming to
market are crossbreds, and often carry some blood of the conti-
nental breeds which for the most part were imported about 1970.
In very recent years we have seen Brahman cattle moving north-
ward in Oklahoma from the breed's traditional stronghold in the
southeastern part of the state.

OTHER CHARACTERISTICS OF OKLAHOMA'S LIVESTOCK INDUSTRY

At least three additional traits help to characterize the live-
stock industry in Oklahoma.

Seed Stock Industry

Oklahoma has historically been important in the genetic improve-
ment and seed stock production of livestock, in some cases far
out of proportion to the importance of the commercial industry
in the state. In the case of beef cattle, of course, it is no
surprise that Oklahoma ranks in the top five in the production
of purebred beef cattle in seven breeds, with four additional
breeds ranking in the top nine. Likewise, it is not surprising
that three separate breeds of horses rank in the top three na-
tionally. It is a bit surprising, however, to find that Okla-
homa has six breeds of hogs ranking anywhere from fourth to
ninth nationally and similarly, three breeds of sheep ranking

4

fourth and another breed 7th.

Performance Testing

Many of Oklahoma’s seed stock producers were pioneers in per-
formance testing. That emphasis on genetic improvement in
traits of economic importance is still evident today, with a
central boar test station and central bull test station among
the largest and most prominent in the country. For example,
approximately 700 bulls are tested each year at the Oklahoma
Beef, Incorporated facility at Stillwater alone. Oklahoma seed
stock producers and Oklahoma State University have a somewhat
unique arrangement wherein the University provides land on a
long-term lease basis plus supervision, and the breeders pro-
vide the facilities and all costs of the performance testing.

Youth Livestock Projects

Oklahoma has historically placed heavy emphasis on youth live-
stock projects, including 4-H and FFA involvement in livestock
shows. The spring Junior Livestock Show in Oklahoma City, for
example, is billed as the largest junior livestock show in the
country. Some people are critical of shows, and there are ways
in which they could be improved, but among other assets they
serve to maintain the interest of young people in animal agri-
culture. The contention that young people will not be able to
adapt to "real life situations" due to the impracticality of
livestock shows is without foundation. Young people are very
astute and are able to maintain their perspective and conse-
quently have no problem in adapting to commercial livestock
production at the appropriate time. Actually, the most promi-
nent carry-over from show involvement is that the young people
tend to transfer the desire to excel to livestock production.

THE FUTURE OF THE LIVESTOCK INDUSTRY

Everyone agrees that animal agriculture in the future faces
some constraints which are largely applicable nationally and
which include at least the following:

1. High production costs

2. Low profits

3. Misinformation (about animal foods)

4. Decreased demand for animal foods

5. Animal rights (and welfare) issue

6. Regulations

7. Waste management

On the other hand, there are some real opportunities ahead in
animal agriculture:

1. Demand for food

2. Technology

3. Domestic markets

4. Foreign markets

5. Producing to meet demand

5

6. Geographic location

7. Climate

Again, most of the opportunities apply nationally, with only
the last two being primarily applicable to Oklahoma. (Okla-
homa's advantages are likely offset by other advantages in
other areas of the country.)

There will be a great increase in demand for food by the end of
the century, which obviously bodes well for animal agriculture.
By the year 2000 there will be a need for 75% more milk, 80%
more beef and 90% more sheep and goats.

Technology represents the most important opportunity over which
the individual producer has control. For example, considerable
research in Oklahoma and elsewhere has shown that with existing
technology most forage-producing operations could double, or
even triple and yes, even quadruple forage production, given
adequate economic reward. Or, on the animal side, research
has shown that beef production can be increased 10% through the
use of two- breed crossbreeding, 20% through the use of three-
breed crossbreeding, 30% if Brahman are included in the cross-
breeding program, 40% if a growthy breed is included in the
crossbreeding program, and 50% if a heavy milking breed is in-
cluded. The list could go on and on.

As we look ahead, we would agree that "we ain't seen nothing
yet" when we think of opportunities which have been projected
through the use of new technology in such areas as genetic
engineering.

KEYS TO SURVIVAL

What does the producer need to do as he looks ahead, to
strengthen his operation, and indeed just to survive? He needs
to do two things: First, he needs to adopt all available tech-
nology that is applicable and profitable in his operation. It
is rather revealing to consider the rates of technology adop-
tion in various animal industries.

Percentage of

Industry Technology Adopted

Poultry

90

Dairy

75

Swine

75

Beef Cattle

40-50

Sheep

40-50

These figures certainly provide a vivid explanation of the past
and certainly provide some warnings for the future. It is
quite apparent that the rate of technology adoption must be
increased with our forage producing animals.

6

Second, the producer must become involved. Historically, the
livestock producer has been a rugged individualist, and has
been proud of it. This has been commendable but the livestock
producers of the future cannot afford such luxury. They must
unite to solve problems, such as those relating to market de-
velopment, public relations and orientation of decision-makers
(political impact) .

CHALLENGE OF ANIMAL AGRICULTURE

Although this applies more to Oklahoma than some areas, we have
two challenges in terms of the agriculture economy. One is to
revitalize the beef cattle sector, primarily through the appli-
cation of existing technology and the development of new tech-
nology as possible and necessary. Second is to diversify ani-
mal agriculture through the enhancement and growth of such
areas as dairy, poultry, swine, sheep and perhaps even in some
cases, horses. We have, in Oklahoma, essentially a two-commo-
dity agriculture (beef cattle and wheat) , and in those years
when prices of beef cattle and wheat are both depressed, the
economy of the state suffers.

OKLAHOMA STATE UNIVERSITY'S ROLE

What do we at Oklahoma State University intend to do about the
constraints, the opportunities and the challenges relating to
animal agriculture? We intend to do three things essentially:
(1) Through research we will develop more technology. The
difficult questions ahead will require both more research and
more sophisticated research, both applied and basic research,
and both biological and economic research. (2) We will become
more effective in our extension programming to facilitate a
higher rate of technology adoption, through such innovations
as educational TV, satellite communications, continuing educa-
tion, expanded use of total mass media, and home video courses
just to mention a few possibilities. (3) In our teaching pro-
grams we will need to "produce" more graduates to meet the in-
creasing needs of high technology production in many areas of
the livestock industry and related agribusiness, and we will
need to do a better job of training the students through empha-
sis not only on the art and science of livestock production,
but on the business aspect as well.

Productivity in animal agriculture in terms of output per fe-
male (cow, sow, ewe) approximately doubled during the 50 years
beginning in 1925. This was largely due to the cooperative
efforts of our system of research and education, the hard
working livestock producer and an effective agribusiness com-
plex. With the same kind of team work in the future, we have
every reason to think that we can more than double productivity
per unit in the next fifty years.

7

The Forage-Livestock Industry in Oklahoma

PASTURE-LIVESTOCK MANAGEMENT SYSTEMS

W. E. McMurphy

Oklahoma State University

Precipitation is a controlling factor in the forage production
in Oklahoma. The eastern one third of the state has an annual
precipitation of over 40 inches and will produce an abundance
of forage, both cool and warm season. The western one third
of Oklahoma receives about one half the annual precipitation
that eastern Oklahoma receives, but the distribution of mois-
ture strongly favors warm season species. Average monthly
precipitation is about one inch from November through March,
five months. The small grains with mostly wheat pasture are
the only viable cool season forages for this western area.

Fescue toxicosis has not been a big problem in Oklahoma, pos-
sibly because not enough fescue is grown. Tall fescue is the
only cool season perennial grass reasonably well adapted to
eastern Oklahoma. However, tall fescue is unreliable as a
source of winter forage. No fall growth was produced in four
of six years in a study near Pawhuska. Ranchers are thus
unwilling to purchase necessary N fertilizer for fall growth
for an unreliable situation.

The rough rocky wooded lands of the Ouachita and Ozark High-
lands Resource Areas that currently produce blackjack and post
oak have great forage potential. Herbicides will control the
woody species. Burning will prepare a seedbed for tall fescue.
Aerial application of seed and fertilizer have been proven
techniques in developing this potential. Unfortunately the
economics of this practice are not practical at the present
time.

Arrowleaf clover is not the major pasture legume of eastern
Oklahoma. This species has three important characteristics
vital to its success: (1) it is a prolific reseeding annual,
(2) it has hard dormant seed, and (3) it grows tall. Perennial
pasture legumes often die during summer drought. The hard

8

dormant seed characteristic provides seed for another crop when
early fall precipitation causes germination followed by drought
which can be lethal to all seedlings. The tall growth charac-
teristic enables it to survive spring grazing mismanagement if
grasses get too tall. Other pasture legumes in use are hop
clover, red clover, white clover, crimson clover, and subter-
ranian clover.

Bermudagrass is the most important introduced grass and occupies
at least six million acres. Many of the pastures in eastern
Oklahoma that are dominated by broomsedge and weeds appear to be
rangeland because that is the way they are being managed.
However, these areas that have bermudagrass present can be
quickly converted to very productive pasture. Mowing in early
June removes the dormant cool season annual grasses and controls
many broadleaf weeds. Then an application of N fertilizer plus
P and K fertilizer if needed will quickly convert these seem-
ingly low productive lands into bermudagrass pastures within a
month.

Winter hardiness has always been a problem with any new bermuda-
grass varieties. The Midland and Hardie varieties are the best
adapted ones for Oklahoma. A five-year grazing test with steers
at Perkins, Oklahoma compared Midland and Hardie bermudagrass .

A three paddock rotation was used with the objective to graze
grass that was between two and three weeks of age. A split
application of N fertilizer was used with 50 lb of N per acre
applied three times each season. Average daily gain was 1.80 lb
for Hardie and 1.61 lb for Midland. Stocking rates were
adjusted with the put and take method to use available forage
and averaged 2.4 steers per acre for Hardie and 2.3 steers per
acre for Midland. Total beef production per acre was 636 lb for
Hardie and 492 lb for Midland. The value of an improved variety
was apparent.

Native range that dominates the grassland resources of Oklahoma
requires a different management philosophy than that of most
introduced grass pastures. The goal of range management for
cattle production is to promote plant succession to the point of
the tallest climax native grasses the site will support. The
goal of pasture management is to prevent plant succession.

Plant succession in rangeland is promoted best by permitting the
grasses to grow, preferably all during the growing season with
grazing done in the dormant season. This deferment when com-
bined with herbicides or fire in special situations is very
effective in promoting plant succession. With season long
grazing on range, the rule of "take half and leave half" must be
followed. It is very necessary to practice this moderate use of
range during the growing season to maintain the necessary root
carbohydrate reserves for plant vigor and competitive ability.
However, these practices do not apply to introduced pasture
species and would be a wasted effort. We prevent plant succes-
sion in bermudagrass pastures by mowing and fertilizing,

9

followed shortly by grazing. On rangeland the practices of mow-
ing, fertilizing, then grazing would be disastrous to the native
climax grasses.

The range manager must be concerned with adjusting the stocking
rate, time of grazing, and degree of use, because he has little
control over the quantity of forage production. Stocking rate
flexibility is necessary. The pasture manager can adjust the
quantity of forage produced with N fertilizer and has more
control over timing of that production through selection of
species planted and timing of the fertilizer application.

Native range grasses have a slow rate of physiological maturity,
and grasses deferred from grazing from May 1 to July 1 are still
good quality forage. This is not true of the introduced forage
species because they have a much faster rate of physiological
maturity with the corresponding decline in forage quality.

The native tall grasses of the True Prairie region have very
slow regrowth following herbage removal after July 1. This is
the result of evolutionary selection pressures. These species
are very palatable, they evolved with grazing, and slow regrowth
is a survival mechanism. There is a vast genetic diversity
within these tall grass species, but any ecotype which evolved
which had rapid regrowth would have been vulnerable. Rapid
regrowth occurs at the expense of the root carbohydrate
reserves, regrowth is very palatable to herbivores, and such
ecotypes probably disappeared from the ecosystem. With such
slow regrowth the native ranges will require a much longer
period of deferment in a rotation system than the introduced
grasses.

The pasture systems of Oklahoma are combined with the native
range resource throughout the state. Management of each
requires different techniques, but the greatest potential for
expansion is with introduced forage species. The technology is
available, but the present economical pressures upon the beef
industry limit its expansion in Oklahoma.

10

The Forage-Livestock Industry in Oklahoma

FORAGE RESOURCES OF OKLAHOMA
P. W. Santelmann
Oklahoma State University

I appreciate the opportunity to present an overview of the
plant resources of Oklahoma. Since it is difficult to talk
about plants without discussing water and soil I would like to
mention these resources also.

The growing of plants for food, fiber, feed, fuel, conserva-
tion, recreation, and esthetics is big business in Oklahoma.
Plant agriculture is important not only as a livelihood for our
farmers and ranchers but also for the well-being of our citi-
zens. We still consider ourselves an agricultural state.
However, the climate in Oklahoma is harsh for plant production.
Rainfall and temperature vary quite widely across the state and
the distribution at any one locality is highly uneven from year
to year. Unseasonable cool temperature, frost, or hot dessi-
cating winds frequently reduce plant growth and crop yields.

The extensive types of crop and livestock production have
dominated agricultural enterprises in Oklahoma since settlement
(as contrasted to intensive). This type of production was best
suited to the state's resources and climate. Forage production
kept pace with the growing livestock industry. Oklahoma soil
and climatic conditions coupled with the intense interest in
livestock makes forage production well suited to the state.

The land devoted to ranges, pastures, and forage crops exceeds
land devoted to cultivated crops by a wide margin. The acreage
in improved pasture has quadrupled in the last 25 years. An
increase in forage production is anticipated - primarily
through improved pasture and range management and the conver-
sion of some ranges into improved pastures.

Water. Certainly one element necessary for successful forage
production is water. The sources of water for both livestock
and man in Oklahoma include farm ponds, large reservoirs, flood
water detention reservoirs, and major streams such as the

11

Arkansas, Cimarron, Canadian, and Red Rivers and their tribu-
taries. In addition a few of our counties have underground
water resources from the Oogalala water formation.

We have over 100,000 farm ponds in Oklahoma. There are 13 large
reservoirs throughout the state but most of the water in these
is not available for agriculture use. Our annual precipitation
varies from about 52 inches in the southeast to 16 inches in the
northwest corner of our High Plains. Almost one million acres
in Oklahoma is irrigated each year, but this is primarily not on
forages. There are exceptions to this as some alfalfa and
bermudagrass are irrigated. Most of the water goes for irri-
gated crops such as cotton, peanuts, soybeans, wheat, and
sorghum.

Soils. There are about 44 million acres of land in Oklahoma.

Our soils vary widely in the nature of their parent material,
their topography, their age, and properties such as organic
matter, pH, and cation status. In general organic matter
content is low - in the area of 1% or less. Soil pH in most of
the state is on the neutral or basic side, but does become
acidic as you get into the higher rainfall areas in eastern
Okl ahoma.

The state is roughly divided into nine resource areas. Of
course there are many different soil series within each resource
area. Starting from the east the Ouachita Highlands in south-
eastern Oklahoma is characterized by a series of parallel ridges
running generally east and west. The rugged surface and sizable
acreages of stoney, shallow soils are developed from weathering
of sandstone and shale. This resource area contains nearly a
half million acres in pasture and rangeland in Classes I through
IV and even more in Classes V through VI.

The Ozark Highlands in northeastern Oklahoma also has a variable
surface relief and comprises about 1.6 million acres. Pasture
and range make up only about 14% of this area. When we get into
the northeast and southeastern corners of the state there are
about 2\ million acres of rangeland in these mountainous areas.
The average stocking rate in this area is about 40 acres per
animal unit (AUY).

The Forested Coastal Plains consist of about one and one-third
million acres in southcentral Oklahoma. Most of these soils are
sandy and are developed from beds of unconsolidated sands, clays
and sandy clays. Pasture and range make up about 15% of this
area.

The Cherokee Prairies consist of 6i million acres of gentle and
somewhat rolling land in eastcentral and northeastern Oklahoma.
The annual precipitation varies from 35 to 45 inches per year.
Low ridges of outcropping sandstone traverse the area and these
soils are generally sandy, shallow, and non-arable . The

12

Bluestem Hills (Flint Hills) are included in the northwest part
of this resource area. Pasture and range comprise over half of
the acreage in this area. In these eastern prairies we find
that the tall grasses are dominant - including switchgrass,
Indiangrass, and the big and little bluestems. The ranges of
this area (about 1.5 million acres) support an average stocking
rate of 10 AUY. This area offers tremendous possibility of
expanded forage production.

The Cross Timbers comprise another six million acres through the
central part of Oklahoma. The surface relief varies from gently
rolling to hilly. The dominant soils are sandstone derived and
under natural conditions support mainly a post oak and blackjack
oak savannah type of vegetation. Soil is very shallow and has a
lower stocking rate than some of the western lands, approxi-
mately 45 AUY. The species prevalent in this 2.2 million acres
of range area are primarily Indiangrass and the bluestems. The
Cross Timber area is rapidly going to improved pasture and we
hope to see this trend continue.

The Grand Prairie in southern Oklahoma contains almost two
million acres. The surface relief ranges from gently wavey to
rolling and hilly. The soils were developed from limestone on
shale under the cover of tall grasses. The soils are predomi-
nately dark colored and heavy or clayey. About 70% of this area
is in pasture and range and forage production can be improved
considerably.

The Reddish Prairie in westcentral Oklahoma occupies a wide belt
through the state and contains about 8i million acres of wavey
to gently rolling surface relief. The soils developed under a
grass cover over weakly calcareous red shales and sandstones.
This area has the highest concentration of cultivated cropland
in the state, but still about 1/2 of it is devoted to pasture
and range. In the Red Prairies there are about 2.3 million acres
of range which has primarily big bluestem, side oats gramma, and
little bluestem and a stocking rate of about 20 AUY.

The Rolling Red Plains make up a large resource area of about 9£
million acres in the western part of the state. Like the rest
of the state it tilts toward the southeast with elevation
ranging from 1000 feet in the east to 3000 feet above sea level
in the west. The surface is rolling with deep cut valleys and
narrow strips of alluvial soils. Most of the 20 to 30 inches of
precipitation occurs between April and September, but the
distribution is irregular and droughts are common. About four
million acres is in pasture and range and comprising primarily
of sand and big bluestem, blue gramma, and little bluestem.

Here the average stocking rate is about 30 AUY.

The High Plains contain almost four million acres of land
sloping from the southeast to a high point in the northwest
almost 5000 feet above sea level. The rainfall is only 15 to 20

13

inches per year. These soils developed from outwash material
imported from the higher elevations of the west. On the High
Plains we find that the dominant forage species are blue gramma,
buffalograss and little bluestem. The range area comprises
about \\ million acres and has a stocking rate of about 40 AUY.

Rangeland. Rangeland and forest range occupy about 20 million
acres, or almost one-half of the land area in Oklahoma. It
includes all lands on which the native vegetation is predomi-
nately grasses, grass-like plants, forbes or shrubs suitable for
grazing or browsing. These include land revegetated naturally
or artificially to provide a forage cover that is managed like
native vegetation. Rangelands in Oklahoma include natural
grasslands, hay meadows, savannahs, shrub lands, abandoned
cropland and areas originally planted to introduce pasture
species but which have reverted to predominately native vegeta-
tion because of a lack of proper management. Rangelands may
also include many forest lands and grazable woodlands in
Oklahoma.

The Oklahoma resouces inventory indicates that about 65% of the
rangeland in Oklahoma needs some type of conservation treatment
to restore the land to its full potential. The primary needs
are for brush and weed control, grazing management and other
range improvement practices which increase range condition,
herbaceous plant production and groundcover.

The role of rangeland in the Oklahoma economy is difficult to
measure because aggregate production data concerning livestock
and other uses of rangeland are not available. However, exist-
ing knowledge and technology applicable to Oklahoma rangeland
could easily double current livestock and wildlife production if
implemented thoughout the state. Too often the focus has been
on range improvements as a cure for improper grazing management.

Pests. Pests on Oklahoma rangeland include primarily weeds,
brush , and insects. There are undesirable plants on most of the
20 million acres of rangeland and forest range. About 11
million of these acres have a serious woody plant problem.

These plants are considered undesirable since they are not
utilized by livestock and compete with desirable plants. The
primary weed problems on rangelands and pastures are broomweeds,
ironweeds, and the ragweeds. In the western half of the state
the problem is dominated by western ragweed and the broomweed.

In the eastern half the problem is dominated by western ragweed
and lance-leaf ragweed. Both the common broomweed and the
lance-leaf ragweed are annuals, and are particularly a problem
following drought years. Most areas are overgrazed during
periods of low production and this allows open spaces for the
annuals to germinate and establish. Western ragweed is a
perennial that spreads both by seed and vegetative underground
stems. Once the plants become established the problem tends to
increase each year.

14

Most of the herbaceous plants have about the same requirement
for growth as the native desirable plants so that there is about
one pound of desirable forage loss for every pound of weeds
produced. Weed production on pastures and range varies consid-
erably throughout the state but about 1000 pounds of weeds
produced is very common and 2000 pounds is not uncommon. There
are normally three control options for taking care of herbaceous
weeds on our forage lands. Grazing is one option that is often
overlooked. It can be very effective and an economical alter-
native. It does require heavy stocking rates for a short period
of time when the weeds are palatable and then removing the
cattle to allow regrowth of desirable grasses. Fair results
have been obtained with prairie threeawn, broomsage, sandbur,
and western ragweed but results with other species such as
western ironweed and common broomweed have been poor.

A second option for controlling weeds is mowing, but it is
primarily a cosmetic option the way that mowers use it.

Although it can be effective in preventing weeds from producing
seed most of the competition has already resulted. There is
also loss of desirable forage from mowing. Burning can best
replace mowing if done properly. The third and probably best
all around option is the use of herbicides to control weeds.

The primary herbicide use for weed control is 2,4-D-which is
effective on many of the broadleaved weeds and is available in a
number of formulations. Dicamba has been mixed with 2,4-D for
specific weed problems. Atrazine is also approved for use on
rangelands. Its primary advantage is its activity on annual
grasses such as the annual bromes and prairie threeawn. Rain-
fall after application is necessary to move the atrazine into
the root zone.

The primary brush problems on the rangelands and pastures of
Oklahoma are the scrub oaks. This ranges from the blackjack and
post oak complex as the dominant vegetation on the sandy soils
of the Cross Timbers and in southeastern Oklahoma to the shin-
nery oak-sand sage complex which is the dominant vegetation on
sandy soils in the western part of the state. Native grass
production on some of these areas is less than 500 lbs. per
acre. Brush is constantly invading the Oklahoma grasslands
since environmental conditions are favorable for brush. It is
estimated that there are more acres of rangeland infested with
brush now than at any time since statehood. Much of this is
attributed to a large increase in eastern red cedar. Some ten
years ago this was a problem on about one million acres, but
today they are becoming a problem on more than 4i million acres
of the Cross Timbers and Reddish Prairie lands. This increase
is attributed to the lack of burning coupled with a large number
of seed trees scattered throughout the state. In addition the
major brush herbicides do not control eastern red cedar.

Brush control options are available but limited. Mechanical
clearing has become very expensive and most desirable sites have

15

already been converted. The requirement that these sites be
"farmed" for two seasons to control resprouts puts a severe
limitation on this option. Mowing is possible on level areas
but is non-effective on most woody species, with the possible
exception of small eastern red cedar trees. In fact mowing will
often increase the number of stems of some species. There is
also a decrease in top to root ratio and this results in less
effective control with any follow up foliar sprays. Burning has
essentially the same limitation as mowing. However both mowing
and burning can be effective on trees that don't resprout. In
fact burning may be the only economical control option available
for cedar control .

Herbicides are the most selective and in most cases the most
economical brush control option available. The major limitation
is that there are currently only a few herbicides that have
label clearances for use on rangeland. For 35 years 2,4,5-T has
been the major chemical but its economic advantage may be coming
to an end. As recently as 1970 a standard application would
cost only $6 to $7 per acre. However, the cost has tripled in
the last 10 years. For many of the oaks treatments for two
consecutive years are needed - which also drastically increases
the cost. Graslan first received label clearance in Oklahoma
and Texas in 1979. It has proven to be an excellent herbicide
for blackjack oak, post oak, and winged elm control on shallow
sandy soils. However, it is very expensive to use, particularly
when one considers the current cattle prices since it takes at
least eight acres of brush converted rangeland to provide enough
forage for one cow per year.

The amount of grass release after spraying depends on the amount
of desirable grass in the treated area, the amount of brush
control, the productivity of the site and the amount of effec-
tive moisture available for plant growth. The highest yield of
grass obtained two or three years after spraying for brush
control was about 4000 pounds per acre and this represented a
four-fold increase in grass production. The actual advantage of
brush control on range usually results in enough increased grass
production to allow a doubling of the carrying capacity in
addition to an increase in the calving percent and the weaning
weight of calves.

Several problems confront range managers and scientists who are
attempting to meet the separate demands of ranchers and society.
Since rangelands inherently have a low production protential and
there is great variability associated with the weather in the
range area the capital investment requires long periods for
benefits to be realized, and are usually not cost effective when
capital costs are high. Higher producing rangelands still
continue to occasionally be converted to cropland and other land
uses while marginal croplands are being allowed to revert to
rangeland. Increases in the densities and the encroachment of
brush species on rangeland reduces their production potential

16

and yet cost effective environmentally acceptable methods of
controlling brush are not generally available for use. Exten-
sive management systems are generally called for on rangeland
but are often overlooked or ignored because they usually do not
result in immediate or sizable increases in production.

Pastures and Forages. Approximately 8.5 million acres in the
state are devoted to pasture, hay, and other tame forage pro-
duction. Forage in this state provides 80% of the nutrients for
beef production and 65% of the nutrients for milk production.
Beef production in Oklahoma has more than doubled in the past 20
years because slaughter weights have remained relatively con-
stant and cattle in feed lots have less than doubled during this
period. Beef production from rangeland and forages has more
than doubled. Significant gains in productivity played a major
role in the total increase in forage production. The average
yield for all hay increased from 1.45 tons per acre in 1958 to
2.12 tons per acre in 1979. Similar productivity gains have
been realized for pastures.

A number of factors have enabled Oklahoma farmers and ranchers
to increase productivity. Development and utilization of more
productive grass varieties and introduction of commercial
fertilizers contributed to the increased production for pas-
tures. On-going research in these areas as well as renewed
efforts and variety improvement will contribute to production in
the future. A number of grass varieties introduced by the
Oklahoma Agricultural Experiment Station has significantly
raised pasture productivity in the State. Notable varieties
include Midland bermudagrass (1953), Morpa lovegrass (1969),
Plains bluestem (1970), and Hardie bermudagrass (1974). Most
recently Brazos bermudagrass, WW Spar bluestem, and Guymon
bermudagrass have been released by various agencies at least
partially as the result of the efforts by Oklahoma grass breed-
ers.

Introduced warm and cool season annual and perennial grasses are
used extensively in Oklahoma either to supplant or supplement
native vegetation. The principle introduced annual grasses used
for pasture or forage are the cool season cereals (particularly
wheat), the warm season sorghum, and the millets.

A significant portion of the winter wheat seeded in Oklahoma
each year is grazed by livestock. Wheat pasture provides a
significant forage support to the beef cattle industry of the
state. However, gains of wheat pasture Stockers are frequently
reduced by 1) inadequate fall or winter forage and 2) snow or
ice cover of wheat pasture. Stability of the wheat pasture
Stocker enterprise could be increased by improved agronomic
practices such as earlier planting dates to increase the amount
of fall and winter forage. While planting dates are influenced
by climatic conditions the optimal seeding date for grain
production (early October) is too late for production of fall

17

forage for winter grazing. However, the extreme variability of
Oklahoma's climate often will not permit early planting or
provide sufficient winter rainfall for best forage production -
which increases the risk factor in buying stocker cattle.

Because of the large amount of the wheat forage that is produced
in the spring there is some potential for increasing gains by
extending the grazing period beyond the traditional March 10-15
cut-off date it grain is to be harvested.

The principle introduced perennial grasses used in the state are
bermudagrass , weeping lovegrass, yellow bluestem, and tall
fescue. The annual and perennial species are often distin-
guished on the basis of their cultural requirement by the terms
cultivated forages and tame pastures respectively. The annual
warm season grasses have high productivity capability and the
forage is of intermediate nutritive value. The major con-
straints associated with their use include high production
costs, insect and disease pests, and in the case of the sorghum
species the potential for hydrocyanic acid poisoning of grazing
animal s.

The introduced perennial grasses used in the state are charac-
terized by high production potential and low energy value. The
principle constraints associated with their production include
establishment difficulties, high nitrogen fertilizer require-
ment, and intensity of management necessary to optimize yield of
digestible nutrients on a consistent basis. The perennial warm
and cool season grass species are further characterized by great
genetic variability and consequently very significant genetic
improvement potential. Much additional progress is needed in
quantifying the effects of management variables on perennial
pasture species and in the development of systems models to
guide decisions for maximizing of their net economic returns.

Although introduced grasses are harvested mainly by grazing
animals, sizable amounts are processed as hay and sold on the
open market. On a per unit basis many of these forage crops
because of their high production potential can compete with
grain crops in the production of protein. Energy efficient
processing methods must be developed however, before this
potential can be fully realized.

Nitrogen fertilizer will continue to rise in cost in the
future because of its natural gas base. Although nitrogen
fertilizer is the most dependable means of increasing forage
quantity and quality, its use on pastures in Oklahoma would
depend on the prices paid to producers for meat and milk. The
best alternative for improved production is more wide spread use
of grass-legume mixtures for grazing. Winter hardiness, growth
during the winter, and drought tolerance are not always satis-
factory for legumes introduced into the state, although some
legumes developed in the southeast produce quite well in
Oklahoma. Legume use will spread to central and western

18

Oklahoma as productive adapted legumes are developed. The
grazing management essential to maintain perennial legumes in a
sward or to optimize production must be developed for Oklahoma
producers to remain competitive.

Alfalfa. Alfalfa production is an essential part of the beef,
horse, and dairy industries of the southern plains and its
importance will continue to increase with higher costs of
energy. It is valued for both the fact that it produces a high
quality forage without annual seeding costs and because it
increases nitrogen levels in the soils, which is valuable if
rotated with other crops. Probably the two greatest problems
with alfalfa production at present are related to harvest
management and to pest control . Losses due to pests represent
the greatest limitations to increased alfalfa production at the
present time in Oklahoma. A variety of insects, pathogens, and
weeds cause reduced production in alfalfa. The most important
forage insect pests include the spotted alfalfa aphid, the blue
alfalfa aphid, alfalfa weevil, and the pea aphid. In addition
seed production insect pests such as lygus bugs and the alfalfa
seed chalcid are important. Many weeds are found in our alfalfa
fields but henbit, winter annual grasses, and pigweed are often
among the more dominant species. Alfalfa stands are not as long
lived as we would like to see in Oklahoma and we suspect that
phytophthora rootrot is a significant cause.

Alfalfa hay is an important part of the income of many southern
Oklahoma alfalfa producers. Four to five cuttings per summer is
the normal procedure in Oklahoma with average yields of 3.3 tons
per acre. Producers generally are able to produce more alfalfa
than they can easily sell at a good price. If marketing pro-
blems can be resolved they will probably be receptive to new
production practices and varieties. Marketing this hay through
the new "Haymarket" program will be of significant help to our
growers.

Alfalfa seed production at one time was important to the state.
This industry shifted to western states using improved produc-
tion practices. The apparent constraints to seed production are
primarily the lack of sufficient numbers of insect pollinators
and the knowledge of their management along with problems caused
by insects that feed on alfalfa seeds before harvesting.

Research is being conducted to try to solve these problems.

Presently pest controls emphasize solutions for individual
problems as they occur. These controls are often quite expen-
sive with little consideration for the most efficient use of the
resources available. For example, use of resistant varieties in
alfalfa production would save producers millions of dollars
annually. Possible interactions between control measures and
the various pest complexes are usually not considered and the
adverse effects of pest regulation practices on non-target
organisms are often ignored. One of the most effective means

19

for controlling many of these pests would be the use of resis-
tant varieties, for which we have an alfalfa breeding program.

Recent research in Oklahoma suggests that harvest management may
be different from that in some of the eastern and northern
alfalfa growing areas. We are finding that the first harvest
can be made well before the first signs of bloom when only a few
small flower buds are observed. Harvesting at this early stage
of growth can help to control weeds by reducing their seed set,
can help control insects by removing the forage and exposing
them to sunlight, and produces a high quality feed without
reducing stand longevity or yield. Similar research has
recently shown that harvesting established stands of alfalfa at
any fall date has little or no effect on spring forage yields
and stand persistence. Alfalfa in Oklahoma may never go
completely dormant and consequently green leafy material remain-
ing after the last fall harvest is present for photosynthesis
and may provide for the plants winter and early spring energy
needs .

There are many problems associated with the production of
forages in Oklahoma. There are also many opportunities in both
our research and our extension activities related to forages.

In spite of these problems we are optimistic about the potential
for Oklahoma to provide its share of the expected increase and
demand for range and tame forages in the United States.

20

The Forage-Livestock Industry in Oklahoma

FORAGE BREEDING PROGRAMS AT THE OKLAHOMA STATE UNIVERSITY
C. M. Taliaferro and J. L. Caddel
Oklahoma State University

Presently there are two forage breeding projects at the
Oklahoma State University dealing, respecti vely , with grasses
and alfalfa. The purpose of this report is to provide an
overview of the work that is in progress in each of these two
projects .

The broad objectives of the grass breeding project are to:

1) develop new cultivars that are superior to existing ones in
such characteristics as adaptation, yield, and forage quality,

2) evaluate new accessions and selections of forage plants to
determine their adaptation and potential value in Oklahoma
agriculture and 3) investigate the reproductive mechanism,
breeding behavior and improvement potential of important and
potentially important forage species. Breeding and/or selec-
tion work is presently underway with four grass species:
bermuda ( Cynodon spp.), introduced (Old World) bluestems
(Bothriochl oa spp. ) eastern gamagrass (Tripsacum dactyloides) ,
and kleingrass (Panicum coloratum). A brief description of the
principle areas of endeavor in each of these species follows.

The bermudagrass breeding program has been underway for several
years and has been primarily concerned with the improvement of
nutritive value in vegetatively propagated varieties. This
work encompasses the interspecific hybridization of high
quality but nonwi nterhardy plants belonging primarily to
Cynodon nlemfuensi s varieties nlemfuensi s or robustus with
well-adapted but relatively low quality plants belonging
primarily to the taxon Cynodon dactyl on var. dactyl on . The
initial interspecific crosses were made in the 1960's and over
the years a modified recurrent selection program has been used
in an attempt to increase the frequency of genes enhancing
forage quality and other physiological and morphological
characteri sties related to yield and adaptation. Progress is
being made in combining the desirable attributes of the

21

parental species. We presently have in our breeding nurseries
progeny selections that are relatively winterhardy and signif-
icantly higher in dry matter digestibility than check cultivars
such as Midland. Although most of the selections of this type
are deficient in one or more performance characteristics
(forage yield, disease resistance, or establishment character-
istics), they serve as parents of progeny populations in which
further selection is practiced.

Another objective of the bermudagrass breeding program is the
development of seed-propagated cultivars for forage and turf
use. In the early stages of the bermudagrass program, some
accessions from the germplasm collection were found to have
relatively good seed set and apparent high seed production
capability. Subsequent testing showed that excellent seed
yields could be produced from fields planted to a mixture of
two such self-incompatible, cross-compatible clonal plants. In
a 3-year study (1974-1976) conducted at the Southwestern
Livestock and Forage Research Station near El Reno, Oklahoma,
an average seed yield of 743 kgs/ha was produced. The parental
plants possessing relatively good fertility and their progeny
populations are winterhardy but do not possess the fineness of
texture desired in a turf cultivar nor the yield potential
desired in a forage cultivar. Hence, we initiated a restricted
recurrent phenotypic selection program for fertility and plant
type. In this program the first level of selection is made for
plant type, i.e., forage versus turf, and then within each of
these categories, selection is practiced for fertility as
expressed by percent of open-pollinated seed set. The second
cycle of selection is presently underway in this program.

The introduced bluestems possess a number of desirable attri-
butes which, in our opinion, will insure their continued use as
pasture grasses in the southern Great Plains. They are easily
estaolished, aggressive, persistent, productive, and have the
ability to tolerate such stresses as drought and overgrazing
but still retain a stand. The Plains bluestem variety was
released in 1972 by the Oklahoma Agricultural Experiment
Station and has been enthusiastically accepted in a large
geographical area on the southern Great Plains. The obligate
and facultative modes of apomictive reproduction found within
the genus make hybridization difficult, but some crossing can
be done between facultative parents and between obligate and
facultative parents where the obligate apomictic parent is used
as the male. Some hybridizations have been made between
Bothriochloa i schaemum and Bothriochloa intermedia in an
attempt to combine the superior winterhardiness of the former
with the greater vigor of the latter species. The majority of
the improvement effort, however, has been directed toward the
selection of existing superior biotypes within the germplasm
col lection.

22

Eastern gamagrass is native to much of the eastern half of the
United States and is generally regarded as a "high quality"
grass because of its superior palatabil ity. Its exceptionally
good palatabil ity to all classes of livestock is attested to by
the fact that it has been eliminated from much of its native
habitat by overgrazing and presently is found only in areas
protected from continuous grazing. Our basic objective with
eastern gamagrass is to elucidate its potential for use as a
grazed or stored forage and to determine the extent of genetic
variation for traits of agronomic importance and the breeding
behavior of the species. Present indications are that there is
a wide array of genetic variation for most of the important
agronomic traits such as yield and quality of forage, and seed
production and its components. However, the most important and
yet unanswered question relates to the basic nutritive value of
the species. The expense and difficulty of establishment and
the necessity for a high level of management that will be
necessary for sustained high yield of gamagrass detract from
its potential and dictate that it must be outstanding in some
other characteristics. That characteristic most logically
should be nutritive value. A cooperative experiment with dairy
scientists was recently completed in which lactating dairy cows
were fed gamagrass and alfalfa hays. The gamagrass hay was
comprised of initial spring growth cut at the boot stage and
5-week old regrowth. The alfalfa hay was also comprised of the
first and second cuttings with each cutting being made at
approximately 10% bloom. Cows fed the gamagrass hay had
significantly less dry matter intake per day (19.20 versus
20.07 kgs/day) than did the cows consuming the alfalfa hay.

Cows consuming gamagrass hay also produced significantly less
milk than did the cows on alfalfa (22.93 versus 24.06 kgs/day).
These results suggest gamagrass may not be too different in
forage quality from other grasses, particularly the Sudan
grasses and sorghum-sudan hybrids. However, data are needed
comparing the performance of grazing animals on gamagrass and
other suitable grass controls in order to more firmly establish
its basic nutritive value.

Kleingrass is a warm-season, perennial, bunch grass indigenous
to Africa. It possesses drought tolerance, is a prolific seed
producer, is easily established, is a little higher in forage
quality than bermudagrass cultivars such as Coastal and Mid-
land, and is valuable as a wildlife habitat for quail and other
wild game birds which thrive on its seeds. Kleinarass is
presently used most extensively in western Texas north to about
34th parallel. Its marginal winterhardiness does not allow it
to be used reliably north of this line and consequently it
cannot be used anywhere in Oklahoma presently. Our sole
objective with kleingrass is to develop a more winterhardy
cultivar that can be used in the southern half of Oklahoma. A
restricted recurrent phenotypic selection program is underway
which encompasses the selection and intercrossing of the most

23

winterhardy field grown plants. Two cycles of selection have
been completed to date.

The basic objective of the alfalfa breeding program is the
incorporation of multiple pest resistance into cultivars that
are well-adapted to Oklahoma. Oklahoma lies in a transition
zone in terms of the amount of winterhardiness needed in
alfalfa cultivars. Cultivars developed for states north of
Oklahoma tend to go dormant earlier in the fall than most
producers would like, while those cultivars developed for
southern and southwestern states, with less severe climatic
conditions than Oklahoma's, do not have enough winterhardiness
to persist under Oklahoma conditions. We are testing germplasm
pools possessing a wide array of dormancy to identify the least
dormancy required for persistence.

Oklahoma has most of the major alfalfa insect and disease pests
found in other alfalfa producing states. These include the
alfalfa weevil, the spotted, pea, and blue alfalfa aphids,
potato leaf hoppers and various foliage feeding caterpillars. A
sizable amount of alfalfa seed is also produced in the state,
and the alfalfa seed chalcid and the lygus bug are major insect
pests of that enterprise. Important alfalfa diseases found
within the state include anthracnose, downy mildew, lepto
leafspot, spring and summer blackstem, and Phytophthora ,
Fusarium and Phymatotrichum root rots. Damage from these pests
in reduced forage yield varies from season to season, but all
will normally be important sometime during the life of a stand.
Emphasis is on the development of germplasm pools containing
high levels of genetic resistance to as many of these insect
and disease pests as is possible. Presently the bulk of the
effort is being spent on the incorporation and/or increase in
the level of resistance to spotted and blue aphids and to
anthracnose and Phytophthora root rot. Conventional greenhouse
procedures are used to screen for resistance to aphids and
anthracnose. In these procedures seedling plants grown in
flats of sterilized soil are infested with the pest organism
and the surviving plants are polycrossed to produce a progeny
population in which subsequent screening and recurrent selec-
tion can be practiced. Phytophthora root rot screening is
presently done primarily under field conditions using irriga-
tion to maintain saturated soil conditions necessary for
disease development. Most of the germplasm pools used in the
Droqram have satisfactory levels of resistance to the oea aphid
and bacterial wilt. All practical efforts are made to maintain
resistance to these pests. Efforts are also made in some of
the breeding populations to retain, or to incorporate, resis-
tance to the alfalfa weevil while increasing resistance to the
other pests.

The goal of this work is, as indicated, to develop germplasm
pools which contain high levels of resistance to multiple
insect and disease pests and from which cultivars well-adapted

24

to Oklahoma and surrounding areas can be extracted. This
project was initiated in 1977. Progress to date has been the
development of broad gene base germplasm pools tracing to six
different source populations: Dormants (from northern Great
Plains), semi-dormants (from southern plains and upper south),
moderately dormant types (Bel tsvil le-6) , Oklahoma Commons
(general adaptation), and Starnes Farm material (for resistance
to weevil and anthracnose) . To each of these pools we have
increased the frequency of genes for pest resistance through
one or two cycles of selection for one to four pests.

25

The Forage-Livestock Industry in Oklahoma

RANGE RESEARCH AT THE SOUTHERN PLAINS RANGE RESEARCH STATION
P. L. Sims

U.S. Department of Agriculture

The Southern Plains Range Research Station (SPRRS) is located at
Woodward, Oklahoma, in the northern part of the Southern Plains.
This research center has direct responsibility for range and
range livestock research in the High Plains, Rolling Plains and
Breaks, Sandstone and Flint Hills, and the Reddish Prairie
resource areas. The long-term average annual precipitation at
the research station is 58 cm, with a range of 25 to 107 cm over
100 years. Approximately 70% of this precipitation occurs
during the summer months. Summer temperatures average 20 C
compared to 7 C in the winter, with a range from -32 to 45 C.

MISSION

The mission of the SPRRS is to increase the efficiency of red
meat production and range resource utilization through inte-
grated management of energy flow, nutrient cycling, and hydro-
logic dynamics in forage-animal production systems in a manner
consistent with perpetuation of the range resource. This
mission is based on the "ARS National Research Program [for]
Improved Vegetation and Management Practices for Range"
(1976), which addresses three broad technological objectives:

1) germplasm enhancement, 2) development of range improvement
practices, and 3) the development of grazing management
systems. The station mission also supports the "Agricultural
Research Service Program Plan" (1983a, 1983b).

PROGRAM INTEGRATION

Five research program areas established for the station include
1) forage germplasm enhancement, 2) forage plant physiological
ecology, 3) rangeland soil-plant relationships, 4) range manage-
ment and plant-animal interaction, and 5) rangeland systems
analysis. Each of these areas is supported by a series of ob-
jectives for research, and approaches vary from process-oriented
studies to integrated interdisciplinary studies. The research
is conducted by a team of scientists composed of an agronomist,

26

plant physiologist, soil scientist, range scientist, and systems
ecologist. The following is a brief synopsis of some aspects of
each of the station's research programs.

Germplasm Evaluation and Enhancement

Old World bluestems. Extensive research with Old World
bluestems (BothriocEloa spp.) has shown that they have signi-
ficant potential for use not only in the Southern Plains but
throughout many regions of the United States. These grasses can
contribute significantly to beef production and soil conserva-
tion. Presently, the primary use of Old World bluestems is to
reclaim marginal croplands interspersed among the region's
rangeland.

Research at the SPRRS helped to elucidate the agronomic,
physiological, ecological, and animal utilization characteris-
tics of the Old World bluestems. For example, basic studies
have shown measurable differences in carbon dioxide exchange
rate, water-use efficiency, and turgor maintenance between
various accessions of Old World bluestems. These characteris-
tics may be related to performance during drought and perhaps
to other stress conditions (Coyne et al. 1982). Such results
indicate that the Old World bluestems comprise a broad
germplasm reservior that can be tapped for specific uses in
forage-based beef production systems in the Southern Plains
and throughout the southeast United States.

These grasses have produced as much as 200 pounds of beef to the
acre under semiarid to subhumid conditions (Sims and Dewald
1982), approximately four times what can be expected from well-
managed native range. 'Plains' bluestem has been interseeded
into an overgrazed mixed-grass prairie site. During subsequent
years total forage production on the site was significantly
increased in comparison to the check plots with no 'Plains'
bluestem (Berg and Sims, in press).

Many grasses such as the Old World bluestems have "chaffy
seed," which is difficult to harvest and process. A seed
harvester has been developed that combines both the flailing
and vacuum principles into one unit for stripping seeds of
this kind (Dewald and Beisel 1982). Work is underway to
develop technology to process the chaffy seed to bare
caryopses and thus facilitate planting.

Eastern gamagrass. Eastern gamagrass (Tripsacum dactyloides) is
a highly productive, extremely palatable grass that has received
sporadic attention from researchers over the last 100 years.

This grass has produced 3 to 4 metric tons of dry matter per
hectare under irrigation at the SPRRS. This grass under optimum
conditions has rapid regrowth potential and provides significant
forage production on relatively fertile lands. A study of
seasonal vegetative establishment and shoot reserves of eastern

27

gamagrass (Dewald and Sims 1981) showed that planting of shoot
bases during the dormant period resulted in excellent stands.
Some recently acquired accessions of eastern gamagrass germplasm
have markedly greater seed production potential than previously
acquired accessions. There appears to be sufficient genetic
diversity in this species to support further germplasm
development (Taliaferro et al. 1982).

Weeping lovegrass. Weeping lovegrass (Eragrostis curvula) has
been studied for more than 30 years. This research has led to
wide usage of this species on sandy lands throughout the
Southern Plains (Shoop et al. 1976, Voigt et al. 1970). Weeping
lovegrass is a highly productive, drought-tolerant, warm-season
species which can be used alone or in complement with native
rangeland or other forages to optimize beef production on some
fragile lands that are subject to wind erosion.

Other species. Work has been conducted on an array of native
species for over 40 years; species studied include sideoats
grama (Bouteloua curtipendula), blue grama (Bouteloua graci 1 is),
sand bluestem (Andropogon gerardi var. hallii), and an
assortment of cool-season species (Mcllvain and Savage 1954).
Currently, a collection of Andropogon gerardi accessions from a
number of habitats is being gathered and grown in a common
garden for detailed physiological and ecological studies that
should lead to a greater understanding of the physiology and the
ecology of this plant species and, ultimately, to an improved
germplasm of this major component of native ranges in the Great
Plains .

Plant-Animal Interaction

A short-duration grazing system is now being evaluated with
yearling stocker steers on native sandhill range. The current
effort includes a 16-pasture system stocked at 120 kg of live
animal per hectare compared to a normal stocking rate of 76 kg
of live animal per hectare for continuously grazed control
pastures. The short-duration system steers are rotated at a
3.5-day interval throughout the year with adjustment for
changing rates of grass growth. Preliminary results indicate
that gains for the short-duration grazing system averaged 62
kg/ha compared to about 35 kg/ha for the continuously stocked
pastures. In this study, forage production, species composi-
tion, litter cover, soil water infiltration, and soil water are
some of the site parameters measured.

Cow-calf research leading to improved forage-livestock manage-
ment systems has been an integral part of this station's
activities since 1940. A native range-complementary annual
farmed forage system developed at the SPRRS has consistently
resulted in weaning weights of around 320 kg from crossbred cows
(Dewald and Mcllvain 1975). This study has been expanded to
include Brahman-Hereford females along with Angus-Hereford

28

cows bred to Simmental sires. These animals and their calves
are being evaluated on the native range-complementary farmed
forages system (4.4 and 0.4 ha, respectively) and on a native
range program (7 ha per cow-calf unit). Cows on the native
range system will be bred to calve in early spring while those
on the native range-complementary forage system are bred for
fall calving.

REFERENCES

Berg, W. A., and Sims, P. L.

Herbage yields and water-use efficiency on a loamy
site as affected by tillage, mulch and seeding
treatments. J. Range Manage. (In press).

Coyne, P. I.; Bradford, J. A.; and Dewald, C. L.

1982. Leaf water relations and gas exchange in relation to
forage production in four Asiatic bluestems. Crop
Sci. 22:1036-1040.

Dewald, C. L., and Beisel, V. A.

1982. The Woodward Flail-Vac seed stripper for harvesting
chaffy seeded grasses for range improvement.

Society for Range Management, 35th Annual Meeting
Abstracts, Calgary, Alberta, Canada, p. 21.

Dewald, C. L., and Mcllvain, E. H.

1975. Forage fed 700-lb. weaner calves today— 1000-lb.
weaners by 1980. Proceedings Forage and Livestock
Conference — with economic considerations for the
producer. Noble Foundation, Ardmore, Okla.

[Dewald, C. L., and Sims, P. L.]

1981. Seasonal vegetative establishment and shoot reserves
of eastern gamagrass. J. Range Manage. 34:300-304.

Mcllvain, E. H., and Savage, D. A.

1954. Progress in range improvement. Adv. Agron. 6:1-65.
Shoop, Marvin; Mcllvain, E. H.; and Voigt, P. W.

1976. Morpa weeping lovegrass produces more beef. J.

Range Manage. 29:101-103.

Sims, P. L., and Dewald, C. L.

1982. Old World bluestems and their forage potential for
the Southern Great Plains. A review of early
studies. U.S. Agric. Res. Ser. Agric. Rev. Man.
South. Ser. No. 28, 15 pp.

Taliaferro, C. M.; Dewald, C. L.; and Bush, L. J.

1982. Tripsacum dactyloides-germpl asm variability and

potential for forage use. Agronomy Abstracts, 1982
Annual Meeting, American Society of Agronomy, p.

154. Madison, Wise.

U.S. Agricultural Research Service.

1976. ARS national research program. NRP No. 20110.

Improved vegetation and management practices for
range. 45 pp. The Service [Washington, D.C.].

1983a. Agricultural Research Service program plan. U.S.
Dep. Agric. Misc. Publ . 1429, 73 pp.

1983b. Agricultural Research Service program plan. 6-Year

29

implementation plan. 1984-1990. 34 pp. The

Service [Washington, D.C.].

Voigt, P. W.; Kneebone, W. R.; McIVvain, E. H.; Shoop, M. C.;
and Webster, J. E.

1970. Palatibility, chemical composition, and animal gains
from selections of weeping lovegrass, Eragrostis
curvul a (Schrad.) Nees. Agron. J. 62:673-676.

30

Forage Plant Resources

BUFFELGRASS GERMPLASM RESEARCH FOR THE SOUTHERN GREAT PLAINS
E. C. Bashaw and C. W. Johns

U.S. Department of Agriculture and Texas A&M University

Buffelgrass (Cenchrus ciliaris L.) is a drouth resistant,
perennial, warm-season species used as a range and pasture
grass in arid areas with mild winter temperatures. It is
apparently native to South Africa, where maximum variation
exists, and extends north into India. Most natural ecotypes
are obligate apomicts and obligate (completely) sexual plants
have never been found in the native habitat. Fortunately the
species is polymorphic, allowing for selection and use of
superior introductions. Some apomictic accessions are being
used for forage in arid regions of several countries and one
strain, introduced into the USA about 1950, is responsible for
over 90% of the revegetation in southwest Texas and north
Mexico. Unfortunately, accessions received in the past have
not had sufficient hardiness for consistent survival north of
San Antonio, Texas and at high altitudes. Significant
improvement in winter hardiness and adaptation to a wider
range of soils could result in extensive use of this grass in
the arid Southwest. This report reviews progress in buffel-
grass improvement and the present status of germplasm
research.

Chance discovery of a sexual '’mutant" in a seed production
field provided the first opportunity for improvement of
buffelgrass. This plant proved to be heterozygous for method
of reproduction and cross-compatible with apomictic ecotypes.
When crossed with apomicts, both sexual and true-breeding
apomictic F^ hybrids were produced. Genetic studies showed
that method of reproduction was rather simply inherited in
buffelgrass and that obligate apomixis could be manipulated
effectively in a breeding program (Taliaferro and Bashaw,
1966). Until recently, improvement of buffelgrass was based
on hybridization of the sexual mutant with apomictic
accessions and selection and evaluation of the best obligate
apomictic hybrids. Crossing the sexual plant with rhizomatous

31

apomicts resulted in some apomictic hybrids with strong
rhizomes and improved vigor, yield and earliness. Protection
afforded by the rhizomes enhanced both winter survival and
persistence under grazing. True tissue resistance to cold was
not achieved in these hybrids but two cultivars, 'Nueces' and
'Llano' (Bashaw, 1981), derived from them are able to survive
about 100 miles further north than any other buffelgrass
because of their rhizomes.

As with most introduced apomictic grasses, lack of adequate
native germplasm and sexual plants for use in hybridization
have been serious problems in buffelgrass improvement. In
1976 we conducted an exploration in South Africa seeking new
buffelgrass sources and acquired over 800 ecotypes with
diverse characteristics and adaption to a wide range of soils.
Some strains with exceptional drouth tolerance were recovered
in a 4 to 8 inch rainfall area south of the Kalahari desert.
Preliminary evaluations of the African collection for drouth
and cold tolerance, vigor, seed production and digestibility
were completed in 1982 and the results indicate that we have
promising germplasm for the milder areas.

Facultative apomictic plants were found among the progeny of
73 of the African accessions and the remaining 733 acces-
sions were obligate apomicts (Table 1). No obligate sexual
plants were recovered from the native habitat. Embryo-sac
studies showed that individual ovules of facultative apomictic
plants may contain: (1) only nuceller sacs, (2) nucellar sacs
and a sexual sac, or (3) a single sexual sac with no evidence
of nucellar development (Johns and Bashaw, 1980). The
percentage of ovules with a sexual sac was low in most
facultative plants (2 to 20%), but there were plants in which
more than 60% of the ovules had a sexual embryo-sac. However,
the percentage of variant offspring was always much lower than
the apparent sexual potential indicating that many of the
sexual sacs did not function in reproduction. Some obligate
sexual plants have been identified among the progeny of 22
facultative plants. A few of the sexual plants are healthy
and highly fertile and represent a valuable source of new
sexual germplasm. However, most were weak and low in
fertility or completely sterile. Over half of the sexual
plants were aneuploid (37 or 38 chromosomes) with several
lagging chromosomes , and embryo-sac studies revealed high
levels of female abortion.

Buffelgrass is apparently a segmental al lotetraploid
(2n=4x=36, typically 2 IV + 14 II at diakinesis) and two or
three lagging chromosomes are common at anaphase I. Sterility
and low vigor of the sexual plants probably resulted from
structural hybridity and accumulated aberrations in the
apomictic parents and from inbreeding depression. These
factors along with environmental effects and grazing pressure
probably account for failure to find sexual plants in the

32

Table 1. — Mode of reproduction and chromosome number
of African buffelgrass accessions

Mode of

Chromosome

No . of

reproduc t ion

numbe r

accessions

Obligate apomixis

36

102

—

576

40

1

42

2

44

43^

45

48

2

54

4

Facultative apomixis

36

676i

45

Obligate sexual

—

0

Cold tolerant ecotypes with an alien genome of 9
univalent s .

natural habitat. The derived sexual plants offer new prospects
for hybridization and expanding the genetic base for
breeding. However, considerable research is needed to
identify the best derived sexual plants for use as germplasm.

Forty-nine nonrhizomatous accessions obtained in a mountainous
area around Beaufort West in the lower Cape Province proved
to be more winter hardy than any previous buffelgrass. These
accessions, representing at least 31 different ecotypes,
survived temperatures of 10 to 20 0 F that destroyed all but
the most rhizomatous strains during the winters of 1978 and 79
at College Station and Temple, Texas. In subsequent tests at
7 locations in north Texas , 6 of the accessions have survived
without winter injury for three years. Further tests are
needed to determine if any of the accessions possess
sufficient winter hardiness to be released as cultivars.

Since dormant tissue of these plants is relatively cold
tolerant compared to the other nonrhizomatous buf felgrasses ,
they represent a valuable source of new germplasm.

Cytological studies were conducted to determine mode of
reproduction and chromosome number and behavior of the cold
tolerant accessions. Six of the accessions were facultative
apomicts and 43 were obligate apomicts. All 49 cold tolerant

33

accessions were found to be pentaploid with 36 buffelgrass
chromosomes and an alien genome of 9 chromosomes that behave
as univalents. The 18 buffelgrass chromsomes pair normally
but the univalents show no tendency to pair among themselves
or with buffelgrass chromosomes. They lag as a group of 9 at
anaphase I and usually divide precociously before telophase.

As a result most diads receive the whole alien genome. We
assume that these plants probably were derived from
fertilization of an unreduced egg in various tetraploid
apomicts and that cold tolerance is conditioned by genes on
the nine univalents.

We hypothesized that significant improvement in winter
hardiness might be achieved if the cold tolerance of these
accessions could be combined with the strong rhizomes of some
of our breeding lines. Two of the most vigorous cold tolerant
strains were used as male parents in crosses with sexual
buffelgrass and 21 hybrids were recovered. All hybrids
contained the normal buffelgrass complement (36) plus one to
nine of the univalents. Twenty hybrids were sexual, and one
containing all 9 univalents was an obligate apomict. Fertility
in the sexual hybrids was low (5 to 20% seed set) but the
apomictic hybrid set 55% seed. These results suggest that
further hybridization should result in hybrids with
significantly better winter hardiness. We have just initiated
studies to identify the most sexual and highly fertile
facultative plants among the cold tolerant strains for use as
female parents in crosses with highly rhizoraatous apomictic
breeding lines. In addition to the usual type of hybrids we
will be looking for plants derived by fertilization of an
unreduced egg in the aposporous embryo sacs. This happens
frequently in apomictic buffelgrass and allows for
simultaneous combination of all the genomes of the female with
the reduced complement of the male.

With a wealth of new germplasm including new sexual parents
and two potentially useful mechanisms for winter survival we
are optimistic that significant advances can be made in
expanding the adaptation of buffelgrass.

REFERENCES

Bashaw, E. C.

1981. 'Nueces' and 'Llano' buffelgrass. Texas Agr . Exp.

Sta. Leaflet L-1819.

Johns, C. W. , and Bashaw, E. C.

1980. New sources of sexuality in apomictic buffelgrass.

Agron. Abstr. p. 58
Taliaferro, C. M. , and Bashaw, E. C.

1966. Inheritance and control of obligate apomixis in

breeding buffelgrass. Crop Sci . 6:473-476.

34

Forage Plant Resources

NEW SOURCES OF GENETIC VARIABILITY IN DALL IS GRASS AND OTHER
PASPALUM SPECIES

Byron L. Bur son and Paul W. Voigt, U.S. Department of
Agriculture, and Wayne R. Jordan, Texas A&M University

Paspalum is a large diverse genus with more than 400 species
(Chase 1929). Common dallisgrass, P. dilatatum Poir. , one of
the more economically important species in the genus , is native
to eastern Argentina, Uruguay, and southern Brazil. It was
introduced into the U.S. in the 1840’s (Chase 1929) and has
spread throughout the southeastern U.S. where it is a valuable
forage grass. Dallisgrass produces good quality forage, is
highly palatable, and persists under heavy grazing. Its most
serious problem is low seed fertility and quality. The grass is
susceptible to ergot, Claviceps paspali Stevens & Hall, and this
undoubtedly contributes to the low seed fertility.

Common dallisgrass has 50 chromosomes that pair at metaphase I
of meiosis as 20 bivalents and 10 univalents (Bashaw and Forbes
1958) . This suggests it is a natural hybrid with chromosomes
from three different sources. The unbalanced chromosome consti-
tution has been preserved because common dallisgrass is an
obligate apomict (Bashaw and Holt 1958). However, apomixis has
prevented any improvement through conventional breeding method-
ology because of the lack of variability in the species (Burton
1962, Bennett et al. 1969). Plant breeders have utilized
several different approaches during the past 50 years in an
attempt to obtain or create variability within common dallis-
grass and/or to circumvent the apomictic barrier. These include
selection of plants from naturalized populations in the south-
eastern U.S., acquisition of plant introductions from South
America, radiation to create desirable mutations, chromosome
doubling, and intra- and interspecific hybridization. For
different reasons, these approaches to obtain or create varia-
bility have been unsuccessful in producing improved forms of
common dallisgrass. For the past several years, our primary
thrust has concentrated on ways to circumvent apomixis . Some
variable forms of dallisgrass have been obtained from these
efforts.

35

PLANT INTRODUCTIONS

On three occasions since 1975, the senior author collected
PaspaZum germplasm in South America. Plant exploration was
concentrated in the region where dallisgrass is considered to
have originated as well as in adjoining areas. These include
southern Brazil, Uruguay, northern Argentina, Paraguay, and
southern Bolivia.

Six different dallisgrass biotypes have been found in the area
considered to be the center of origin of the species (table 1) .
The common, prostrate and erect yellow-anthered bio types have
been available to plant breeders in the U.S. for many years.
However, a large number of phenotypically different ecotypes of
common dallisgrass representing variability not previously
available have been collected since 1975. Only one or two
accessions of the variable yellow-anthered biotype from a small
region in the northeast part of the state of Rio Grande do Sul
in Brazil were available prior to 1975. The recently acquired
accessions were collected from a broader area of their native
habitat and are considerably more variable than the previously
available accessions. There is a wide integradation of types
ranging from plants similar to vaseygrass, P. UTVillei Steud.,
to the more typical yellow-anthered dallisgrass . It appears
that natural hybridization is occurring between vaseygrass and
yellow-anthered dallisgrass. These accessions and their progeny
provide valuable sources of new germplasm and sexuality to use
in the hybridization program. Two biotypes, the Torres and
Uruguaiana dallisgrasses , had never been available through the
U.S. Plant Introduction program. Both biotypes are considerably
different from common dallisgrass (table 1) and the Uruguaiana
biotype appears to have potential as a forage grass.

A forage evaluation test was conducted at Temple, Texas, from
1978-1980 to determine the forage potential of 17 different
biotypes including common dallisgrass. Forage yields and IVDMD
values for the accessions are presented in table 2. The erect
Uruguaiana biotype produced more forage than common dallisgrass.
The four common dallisgrass ecotypes which were phenotypically
different than typical common dallisgrass produced less forage
than common, and the Torres biotype produced the least amount of
forage.

The IVDMD values for all the accessions were low because the
samples were collected when the plants were mature. Common
dallisgrass did not differ significantly from the other acces-
sions in IVDMD (table 2) , but there were significant differences
among the Uruguaiana types in IVDMD. Because there was not a
significant correlation (r = -0.28) between yield and IVDMD for
the Uruguaiana accessions, we believe that we may be able to
select a more productive plant without adversely affecting
IVDMD, but more detailed studies are needed. In 1982 the seven

36

Table 1. — Biotypes of Paspalum dilatatum from South America

G

o

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G

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G

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54

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54

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54

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t — 1

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0

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5>4

G

>m

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H

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37

Table 2. — Performance of new dallisgrass ecotypes and biotypes

Accession

Type

Forage yield

Mean IVDMD

kg /ha

%

461

Uruguaiana

8300 a

47.8 bed

455

II

8300 a

47.6 bed

426

II

7600 ab

48.0 bed

554

II

7600 ab

49.5 abc

458

II

7500 abc

47.5 cd

460

II

7400 abc

46.9 d

555

II

7300 abc

50.1 ab

427

II

6800 bed

48.0 bed

432

II

6500 b-e

47.3 cd

459

II

6500 b-e

48.0 bed

544

II

6300 c-f

50.5 a

Mean

II

7300

48.3

Common

Common

6300 c-f

48.6 a-d

552

Common off type

5900 d-g

49.7 abc

543

II II II

5500 efg

49.0 a-d

547

11 II II

5200 fgh

47.4 cd

351

II II II

5000 gh

48.0 bed

Mean

ft II II

5400

48.5

178

Torres

4000 h

48.4 a-d

lean of 3 years.

38

best accessions and common dallisgrass were planted into forage
tests at Temple and Angleton, Texas, for further evaluation.

Because previous plant breeders and geneticists have used plant
introductions in an attempt to improve the species, it may seem
unusual that this approach is more successful today. Essen-
tially all Paspatum introductions obtained prior to 1975 were
collected by taxonomists from the countries where the plants
were growing. Because they were unaware of the objectives of
the breeding programs and did not understand the problems asso-
ciated with breeding apomictic grasses, their collections did
not comprise the best available germplasm. The senior author
was familiar with these problems, and therefore was able, with
the assistance of South American scientists, to identify valu-
able new ecotypes and biotypes not included in previous collec-
tions. This clearly demonstrates the necessity that the
geneticist working with a particular species to explore the
center of origin of the species and collect the diverse germ-
plasm that will be of value to the improvement program.

Accessions of four other Paspalum species are also being evalu-
ated at Temple. The species are P. nicovae _, P. plioatulim j P.
denticulatwn , and P. unispicatum.

INTRA- AND INTERSPECIFIC HYBRIDIZATION

Numerous interspecific Paspalum hybrids have been made during
the past several years. Many of these have involved the erect
sexual yellow-anthered dallisgrass biotype as the female parent.
Most hybrids were made for cytogenetic analysis to determine the
phylogenetic relationships among various species (Burson 1983) .
Even though some hybrids have potential as productive forage
grasses, they all lack sufficient fertility to be propagated by
seed. Attempts to restore fertility in these hybrids have not
been successful.

Because of sterility in the interspecific hybrids, intraspecific
hybridization appears to have the most potential in producing
improved germplasm. A fertile intraspecific hybrid has been
produced between the yellow-anthered and common dallisgrass
biotypes (Bennett et al. 1969). However, because of the insta-
bility of the 10 common dallisgrass univalent chromosomes in the
Fj hybrid, apparently some important genetic material is lost
when the 10 univalents are eliminated in the subsequent genera-
tions. Recently, this yellow-anthered X common Fj hybrid was
backcrossed to common dallisgrass, and some variable purple-
anthered plants have been recovered. This could provide a means
of stabilizing some of the univalents as backcrossing to common
dallisgrass is continued. In the future the sexual yellow-
anthered plants will be crossed with the Uruguaiana biotype in
an attempt to recover improved types.

39

TISSUE CULTURE

Variation is observed frequently in tissue culture-derived
plants. When small segments (3-5 mm in length) of young common
dallisgrass inflorescences or stems are placed on an agar based
medium, callus tissue often develops. After the callus has
increased to a sufficient size, it is transferred to other media
with appropriate auxin-cytokinin content to stimulate shoot and
root differentiation. These young plantlets are transplanted
into peat pots in the greenhouse and eventually planted into a
field nursery.

More than 300 plants have been established in a field nursery.
Differences in plant size, leaf width, leafiness, and pubescence
have been noted. Because we are interested in increasing
drought tolerance in dallisgrass, a study was initiated to
determine if there were differences in heat tolerance among the
tissue culture-derived plants. Using a heat tolerance test
(Sullivan 1972) , 250 plants were tested under both drought
stressed and non-stressed conditions. When drought stressed,
the percent cellular damage from a heat challenge of 50°C for
45 min ranged from 20 to 70% with the largest number of plants
occurring in the 50% damage category. The common dallisgrass
control was also in the 50% damage category. Plants were
visually rated for their susceptibility or resistance to stress
when under drought conditions. The visual ratings and the
cellular damages from the heat tolerance test were negatively
correlated (r = -0.32**). When the plants were sampled under
non-stressed conditions, the percent damage ranged from 60 to
100% with the most frequent category being 80%. Common dallis-
grass was in the 80% category. These findings suggest that
differences occur among the tissue culture-derived plants in
their ability to acclimate to heat or drought stress . Because
common dallisgrass is an obligate apomict, this amount of varia-
bility would not normally be expected and, in fact, was not
observed among the common dallisgrass checks. Therefore, it
appears that real differences do occur in the tissue culture-
derived plants. Research is underway to further evaluate the
physiological and genetic bases for these differences under
controlled conditions. Variants produced in this manner may be
important in extending the range of adaptation of common dallis-
grass into drier regions.

40

references

Bashaw, E.
1958.

Bashaw, E.
1958.

Bennett, H.
1969.

Bur son, B.
19-83.

Burton, G.
1962.

Chase, A.
1929.

C., and Forbes, I., Jr.

Chromosome numbers and microsporogenesis in dallis-
grass Paspalum dilatatum Poir. Agron. J. 50:
411-445.

C. , and Holt, E. C.

Megasporogenesis , embryo sac development and embryo-
genesis in dallisgrass Paspalum dilatatum Poir.
Agron. J. 50: 753-756.

W.; Burson, B. L.; and Bashaw, E. C.

Intraspecific hybridization in dallisgrass, Paspalum
dilatdtum Poir. Crop Sci. 9: 807-809.

L.

Phylogenetic investigations of Paspalum dilatatum
and related species. In J. A. Smith and V. W. Hays
(eds.), Proc. 14th Int . Grassl. Congr., Lexington,
Ky., 15-24 June, 1981, pp. 170-173. Westview
Press, Boulder, Colo.

W.

Conventional breeding of dallisgrass Paspalum
dilatatum Poir. Crop Sci. 2: 491-494.

North American species of Paspalum. Contr. U.S.
Natl. Herb. 28(1): 1-310.

Sullivan, C. Y.

1972. Mechanisms of heat and drought resistance in grain

sorghum and methods of measurement. l!n N. G. P. Rao
and L. R. House (eds.). Sorghum in the Seventies.
Oxford and IBH Publishing Co., New Delhi, India.

41

Forage Plant Resources

CLOVER AND SPECIAL PURPOSE LEGUME GERMPLASM RESOURCES
FOR THE FUTURE

Gary A. Pederson and William E. Knight
U.S. Department of Agriculture

INTRODUCTION

Between 1950 and 1970, research on clovers and special purpose
legumes was greatly reduced in the U.S.; however, in the last
ten years, interest has rekindled in the utilization of legumes
in pastures and in conservation tillage systems. The energy
crisis stimulated part of this interest as well as a need
perceived by livestock producers for higher quality forage with
better seasonal distribution. Recent economic conditions in the
livestock industry have resulted in erodable land being placed
in row crops. Increased erosion clearly shows the need for
better conservation tillage systems. Legumes should be an
integral part of these systems.

Presently, there are 75 legume species (excluding alfalfa) in
public improvement programs in the Southeastern U.S. This paper
will summarize the state and the U.S. Department of Agriculture
programs involved in improvement of these 75 legume species.
Also, examples of current research that will result in improved
legume germplasm for the future will be cited.

AREAS FOR IMPROVEMENT

There are a number of areas where significant improvement can be
made in the germplasm of the future:

1) Increased forage yield distribution and quality.

2) Resistance to fungal pathogens.

3) Resistance to legume viruses.

4) Nematode resistance.

5) Insect resistance to primary pests as well as to vectors of
viruses .

6) Improved N2 fixation by developing a more efficient symbio-
tic relationship with improved Rhizobium strains.

42

7) Increased drought tolerance and winterhardiness to improve
persistence and increase adaptation of legumes to South-
eastern U.S. climatic conditions.

8) Improved seed production to enable producers to establish
initial stands and improved reseeding in annuals for
establishment of subsequent stands.

9) Development of interspecific hybrids to utilize traits from
other legume species.

10) Plant introduction and evaluation to broaden the gene base
and reduce genetic vulnerability.

WHITE CLOVER

White clover, Trifolium repens L. , is a perennial clover widely
adapted for use in pastures of the Southeastern U.S. Alabama,
Florida, Louisiana, Mississippi, North Carolina, and South
Carolina are presently involved in white clover improvement
(table 1). The standard white clover cultivars are the ladino
types, 'Regal' and 'Tillman', and the intermediate types
'Louisiana S-l' and 'Nolin's Improved'. Regal is a five-clone
synthetic released by the Auburn University Agricultural Experi-
ment Station in 1962 (Johnson et al. 1970) while Tillman, a
six-clone synthetic, was released by the South Carolina Agricul-
tural Experiment Station and the U.S. Department of Agriculture
in 1965 (Gibson, Beinhart, and Halpin 1969). Louisiana S-l, a
five-clone synthetic released by the Louisiana Agricultural
Experiment Station in 1952 (Hollowell 1958), and Nolin's
Improved, a naturalized cultivar, behave as reseeding annuals
in the Southeast.

Objectives of white clover research include improvement of per-
sistence and development of resistance to viruses, root dis-
eases, and nematodes. Prior to retirement. Dr. P. B. Gibson led
an extensive and productive multidisciplinary program on white
clover at Clemson, S.C. He led a research team that produced 11
interspecific hybrid combinations, eight for the first time,
among five species of clover (Chou and Gibson 1968; Gibson and
Beinhart 1969; Gibson et al. 1971; Gibson and Chen 1975) . The
Clemson team developed a technique to screen white clover plants
for resistance to root-knot nematodes (Baxter and Gibson 1959)
and released SC-1 root-knot nematode resistant germplasm in 1972
(Gibson 1973). A forthcoming virus- resistant germplasm release
was developed through a five-state cooperative project coordi-
nated by Dr. P. B. Gibson. Plants were screened by mechanical
inoculation, aphid inoculation, and field tests for resistance
to alfalfa mosaic virus, peanut stunt virus, and clover yellow
vein virus. Further field screening resulted in 44 clones being
found resistant to these viruses in all tests. A germplasm re-
lease of this material will be made shortly. Other promising
white clover germplasm includes Florida XP-1 and XP-2 developed
by the Florida Agricultural Experiment Station and the Brown
Loam germplasm developed by the Mississippi Agricultural Experi-
ment Station and the U.S. Department of Agriculture.

43

Table 1. — Forage legumes other than alfalfa in public improvement programs
in the Southeastern United States^

M

3

&

•

CO

3

/—N

e

o

3

6

/•—N

3

1 — 1

•H

3

/^*N

3

4-1

• •

3

5-4

4-1

s

i — 1

3

/- — \

u

CO

T3

3

3

•H

3

•

•H

3

3

3

3

H

•H

a

CO

05

3

5-i

6

3

3

a

a

05

a

X

3

3

•H

4-1

3

C0

>

CO

05

O

3

i — 1

3

3

05

i — 1

3

50

3

6

3

e

5-1

3

•H

■H

H

3

3

H PO

a

•

•H

> — '

•H

, S

•H

t—

i •

i — 1

£

H H

1 ^

6

H|

O

M— 1

'■w'

44

cd

•H

05

H|

1 6

3

H H

|H

3

5-i

i — 1

''w'

3

O

4-/

s — *

•H

3

H

S

3

CO

H

•H

' — '

o

r— 1

CO

6

3

3

3

3

!-i

i — 1

3

•H

3

4-1

3

CO

5-1

cd

3

3

3

•H

3

3

S-i

<

PQ

PQ

C_>

S

a

Pi
CO PQ

n

3

3

5-i

3

a

5-i

3 a)
a co
c a

• 3 -1-1

H| -U 5-i

"■ — ^ CU *H

5-1 rC

6 a

d • o 3

3 • h h a>

5-1 Hi'-' -H ,£3

3 as

a 3 *h 3

m 'd co g 5-1

4-1

•sc -sc -sc

H H H

a pd a

•SC

-sc

*

•SC

t-H

C\]

I— 1

CN

CN

CN

Pi

a

a

a

Pi

Pi •

«■.

•SC

*>

■SC

*>

»• •

PQ

CO

PQ

CO

CO

CO

PQ

PQ •

CO

CO

CO

CO

CO

CO

CO

CO

CO

CO

CO

PQ •

CO CO CO

CO

CO CO

CN

Ptf

CN

CN

CN

rH

• • t—l

Pi

Pi

Pi

Pi

• t—l

• • Pi

• Pi

• • rv

CO

PQ

CO

PQ

•

• • CO

• CO

•SC -5C

rH

i — 1 t—l

ptf

Pi Pi

•SC

*

»>

PQ

PQ

PQ

B

B

i — 1

3

3

• ✓ — N

•H

3

3

3 3

Ou

4-4

4-1

3 3

•H

•H

H

/-v

3 *H

6

50

3

•

3

•H i— 1

a)

3

3

3

4-1

3 O

•

CO

3

/—N

6

3

3

3 4-4

4-4

3

O

3

a *h

N

H

3

•H

3

3

3

3 4-1

3

H •

3

33

4-1

t — 1

3

a

•H 3

3

H

a

3

3

3

a

a r3 3

X>

3

3

6

•H

a

3

50

t—l

6

3

3

3

•H

3

3

3

4-1

4-1

H 3

H| 3

3

3

3

,H|

1 10

3

3

3 3 O 3

3 H | w
5-1

5-4 50

3 3 3 ••
4-1 4-1 N 3
X -H 50 N

3 -3 *H 3
Pi CO CO CO S N 3
05

a

CO
05

. • cd

h| ail 05

•H
5-i
05

3 H|'
O

I — I

O 05
a 3 •

co 05 Cd PQ
3

44

Table 1. — Forage legumes other than alfalfa in public improvement programs
in the Southeastern United States — continued

x

H

w cn m co w w w

PS pS
PP PP

>1

s-j >|

PO g
•H O
pq O

> CO
w OJ

g

co co co co co co

cd

Cl

d

d

cd

CO

cd

o

cd

u

•H

g

i — i

PC

o

•H

d

d

i — i

Ci

•H

CO

cd

•H

•H

cd

X

•H

cd

Cl

d

u

<u

r— 1

i— (

4J

cd

o

o

g

<d

•rH

cd

d

Cl

Ci

cd

<> — -

CO

i — i

cu

g

o

cu

cd

d

C

d

u

4-1

d)

cd

Cl

C

o

cd

g

d

cu

£

>

cu

x>

•H

d

cd

ds

0)

cd

•H

>

CO

cd

Cl

•H

,d

g

4-)

4-1

o

cd

cd

g

o

d

o

g

o

cd

CO

•H

rH

rd

M— 1

cu

d

•H

4-J

d

d

u

•H

CO

u

1 1

CO

o

PO

d)

*H

X

i — i

d

cd

cd

o

CO

Cl

>

dd

cd

d

cu

CU

>

•H

Cl

cd

•H

d

O

o

4-4

u

CO

O

cd

CO

4-1

d-

>

g

CO

X

d

CO

d

o

CO

d)

•

•

rH

cd

cd

(U

•

Ci

<u

<

C|C|<3

1 <J

o

o

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o|u|u

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Q|Q|Q|Q|Q|

45

sandwicense

Table 1. — Forage legumes other than alfalfa in public improvement programs
in the Southeastern United States — continued

pi

CO PQ CO

><

•X

r~H

X

<

o

X

r-H

X

pi

p-l

CO

CO

*>

CO

X

X

<

X

'rl

X

x

•

CO

3

bO

•

cd

3

X

X

•

4-1

co

X

3

S

3

3

4-J

X

CO

3

3

X

3

5-4

3

3

, V

3

•H

•H

3

S

3

X

3

•

n

•

a,

CO

3

bC

O

/"-'N

3

3

3

X

3

•

cd

3

Q

X

3

O

3

5-1

X

v — /

3

•H

3

•<— >

03

3

X

O

3

3

<4-4

X

/— s

3

3

3

a

3

a

X

o

6

3

X

3

I — 1

5-4

3

X

2

X

0)

bO

3

X

3

3

3

3

<

v '

3

X

6

•H

■H

X

i —

O

X

T— I

3

X

3

3

3

T3

5-i

3

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i — 1

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r— 1

3

o

pj

3

3

60

3

3

3

X

3

X

3

X

•H

O

3

X

3

3

X

3

4-)

W

3

X

3

3

X

X

i — 1

3

3

3

— i

3

X

03

'w'

O

*

X

s

O

3

3

i — 1

3

3

X

3

P,

*H

5-1

3

CO

X

3

3

3

3

3

•H

X

3

X

O

O

3

o

3

X

3

3

3

b0

pL,

3

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' <■

3

X

bO

3

3

X

3

CO

3

X

3

O

X

' — *

a

3

3

CO

•H

X

a

X

3

i — 1

3

6

5-i

X

3

CL,

XI

6

X

3

X

o

0

X

3

rH

X

3

X

3

3

3

c!

X

CO

O

3

i — i

i — 1

3

3

3

3

Cl,

3

•H

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3

4-J

o

•H

3

3

3

X

3

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•H

3

4->

3

3

Q

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3

X

X

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3

X

3

3

O

o

CO

•H

1!

3

X

3

3

o

3

3

3

3

O

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3

5-4

>>

a

N— "

•H

X

3

O

X

3

O

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3

3

3

CL,

i— i

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3

1 — 1

3

X

3

6

3

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cd

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I — 1

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3

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s

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s

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CX

P-4

Ph

PL| I P-l I

46

scandens

tetragonolobus

Table 1. — Forage legumes other than alfalfa in public improvement programs
in the Southeastern United States — continued

x

H

WWW

o

CO

o

S3

CO CO CO CO CO

c3

pq

6

P

CL)

5-1

P

CO

a

p

5-1

p

q>

cd

a

i — i

o

P

!-i

a

4-1

CO

•H

cd

co

•H

P

cu

i — 1

P

6

XI

•H

O

q)

•H

e

o

•H

O

qJ

cd

i — 1

5-1

si

cd

CO

1 — 1

•H

X

CO

cd

p

p

r— 1

4-)

,P

CO

•H

a)

cd

p

cd

O.

P

cu

CO

o

rH

o

o

O

cd

-P

p

•H

P

hJ

o

cd

P

i — l

p

cd*

cu

cd

P

o

w

p

i — i

.. o

p

p

p

P

CU

p

cd

o

o cd

•

cd

cd

cd

s>

CO

cu

rH

o

(U

p S

2 cn

S

■H

cd

P

.a

•H

4-4

p

o

cd

P

u

P

p

O

cd

P

cd

1— 1

rP

00

CO

CO

p

4-4

P

5-1

>>

CU

00

•H

p

P

•H

CO

CO

CO

co

|co|co|co|H

>

>1

Pj

cd (P
cu co
cx

5-i cd
(U *H
P P
P P
•H O

00

P
•H
X)

cu
a)

P

pq w

II II

i— I CN

pq co p3 Pi

47

Evaluation and selection.

Released germplasm or cultivar.
Release probable within 5 years.

RED CLOVER

Red clover, Trifolium pratense L., is a perennial clover which
is more widely used in other areas of the U.S. other than the
Southeast. Florida, Kentucky, and Louisiana are involved in
improvement programs on red clover (table 1). For the Southeast,
the standard cultivars are ’Kenland' and 'Kenstar'. These two
cultivars were developed by the Kentucky Agricultural Experiment
Station and the U.S. Department of Agriculture in 1951 (Hollowell
1951) and 1973 (Taylor and Anderson 1973), respectively.

Objectives of red clover improvement programs include increasing
persistence in the Southeast, developing fundamental cytogenetic
knowledge on Trifolium species, and increasing resistance to
viruses, root diseases, and nematodes. Dr. N. L. Taylor and
associates at the Kentucky station have established an extensive
red clover improvement program. Recent red clover germplasm re-
leases include 11 gene markers (Taylor 1982) and 9 generations
of bulked plant introductions (Taylor 1979) . The Kentucky pro-
gram has also been instrumental in interspecific hybridization
of Trifolium species and has released germplasm of Trifolium
sarosiense x TL alpestre and Trifolium medium x T_. sarosiense
in 1978 (Taylor and Quesenberry 1978a, 1978b) .

ARROWLEAF CLOVER

Arrowleaf clover. Trifolium vesiculosum Savi. , is a winter an-
nual clover that has received a great deal of interest in the
Southeast recently. Florida, Georgia, Louisiana, Mississippi,
and Texas are involved in arrowleaf clover improvement (table 1) .
The standard cultivars of arrowleaf clover are ' Amclo ' , 'Yuchi' ,
and 'Meechee' . Amclo, an early-maturing cultivar, was released
by the Georgia Agricultural Experiment Station and the U.S.
Department of Agriculture (Beaty et al. 1965). Yuchi, a later-
maturing type, was released by the Auburn University Agricultural
Experiment Station (Hoveland 1967) . Meechee, the latest maturing
cultivar with the most winterhardiness, was released by the
Mississippi State University Agricultural Experiment Station and
the U.S. Department of Agriculture (Knight et al. 1969).

The objectives of arrowleaf clover research are to obtain early
emergence with uniform stands, increase late spring persistence,
improve drought tolerance, and increase resistance to viruses,
root diseases, and nematodes. Virus diseases are a major pro-
blem not only in arrowleaf but in many of the other true clovers.
Viruses can reduce the clover stand by direct effect or by in-
creased susceptibility to secondary pathogens through reduced
plant vigor. Arrowleaf clover is more susceptible to nematode
damage than other annual clovers (Nichols et al. 1981). Nema-
tode-resistant germplasm should be forthcoming from the Florida
breeding program.

48

CRIMSON CLOVER

Crimson clover, Trifolium incarnatum L., is a winter annual le-
gume with a distinctive bright crimson flower. Florida,

Kentucky, Louisiana, Mississippi, and Texas have active im-
provement programs in crimson clover (table 1) . The standard
cultivars are ’Dixie’, ’Chief', ’Autauga’, and ’Tibbee’. Dixie
was released in 1946 by the Georgia Agricultural Experiment Sta-
tion and the U.S. Department of Agriculture (Hollowell 1953).
Chief and Tibbee were released by the Mississippi Agricultural
Experiment Station and the U.S. Department of Agriculture
(Hollowell 1960 and Knight 1972) .

The objectives of crimson clover research are to improve N£ fix-
ation, improve fall growth, reduce seed shatter and lodging, and
increase resistance to the clover head weevil, viruses, root
diseases, and nematodes. The clover head weevil is a major in-
sect problem on crimson clover. Feeding by this insect reduces
the reseeding ability of crimson clover and may result in poor
stands in subsequent years. A screening program is presently
underway in Mississippi to develop resistant germplasm.

SUBTERRANEAN CLOVER

Subterranean clover, Trifolium subterraneum L., is a winter an-
nual clover which only recently has been extensively grown in the
Southeast. Florida, Georgia, Louisiana, Mississippi, and Texas
are involved in the improvement of subclover (table 1) . The
standard subclover cultivars are ’Mt. Barker’ , ’Nangeela’ ,

’ Woogenellup ’ , and ’Meteora’ , which are imported from Australia.
Objectives of subclover programs include evaluation of
Australian material for adaptation to the Southeastern U.S.,
increasing forage yield, improving reseeding ability, and
developing resistance to viruses and mildew. A subclover germ-
plasm with increased adaptation to the Southeast has been de-
veloped by the Mississippi Agricultural Experiment Station and
the U.S. Department of Agriculture. The Mississippi ecotype
subclover has persisted for over 30 years from an original seed-
ing of the Australian cultivars Mt. Barker, ’Bacchus Marsh’ ,
and ’Tallarook’. This subclover will be released as germplasm
or as a cultivar in the near future.

BERSEEM CLOVER

Berseem clover. Trifolium alexandrinum L., is a winter annual
clover that is in the improvement programs of Florida,

Louisiana, Mississippi, and Texas (table 1). Presently, there
are no standard cultivars for the Southeast except Florida
since no cultivars have adequate winterhardiness. The main ob-
jective of berseem clover improvement is to increase the winter-
hardiness of the species. Secondary objectives include deve-
loping resistance to leaf diseases and improving recovery after
clipping. A winterhardy berseem clover has been developed in

49

Mississippi from plants of the Italian cultivar 'Sacromonte'
that survived field temperatures as low as 5° and 8° F. A re-
lease of this material will be made shortly.

PERSIAN CLOVER

Persian clover, Trifolium resupinatum L., is widely adapted
in the South. Producers' fear of bloat has caused this species
to fail to reach its potential as a forage crop. A wide range
of plant material, representing wide variations in maturity,
forage yield, and recovery after clipping, is available through
plant introduction (Massey 1966) . Weihing (1962) applied selec-
tion pressure for hard seed to desirable agronomic types from
three plant introductions to develop the improved, hard-seeded
cultivar 'Abon'. Reluctance to use Persian clover should di-
minish with present knowledge and use of poloxalene in blocks
and in molasses mixtures.

Interest in Persian clover has increased, and Abon is being eva-
luated in regional tests.

BALL CLOVER

Interest in ball clover, Trifolium nigrescens L., has increased
in Alabama, Mississippi, and Louisiana. The Alabama Experiment
Station includes this species in its improvement program.
Breeding objectives in this program are 1) increased forage and
seed yield, and 2) improved pest resistance. Recently a farmer
variety, 'Segrest' was added to the regional variety tests, and
the Alabama station plans to make a germplasm release in the
near future.

VETCH

Vetches are used most commonly as winter cover crops in the
Southeast, with 75% of the total acreage in Oklahoma, Arkansas,
Texas, and Louisiana. However, vetch makes hay, silage, and
pasture of high quality. Hairy vetch, Vicia villosa Roth,
accounts for 85% of the vetch acreage in the U.S. In 1959, the
Alabama Agricultural Experiment Station released 'Warrior', a
variety of common vetch, Vicia sativa L. (Donnelly 1965a) .
Warrior vetch is resistant to the vetch bruchid and three
species of root-knot nematode and produces high forage and seed
yields .

The Louisiana Seed Company is distributing seed of four proprie-
tary varieties from the Alabama program (Donnelly 1979) . These
recent releases are 'Vantage', 'Cahaba White', 'Nova II', and
'Vanguard' .

At the Kentucky Agricultural Experiment Station, a locally
adapted strain of bigf lower vetch, Vicia grandif lora var.
kitaibeliana W. Koch, has shown promise as a pioneer legume in

50

pasture renovation research conducted by Templeton and Taylor
(1975). 'Woodford' has been released as a new variety of big-
flower vetch from this work.

LESPEDEZA

Both perennial and annual lespedezas have been under evaluation
for use in the Southeast. Most of the current research is on
the perennial sericea lespedeza, Lespedeza cuneata (Dum.) G. Don,
rather than the two annual lespedezas — striate, Ij. striata
(Thunb.) Hook & Arn. , and Korean, L^. stipulacea Maxim. Alabama,
Kentucky, Louisiana, and North Carolina are involved in sericea
lespedeza improvement (table 1) . The main objectives of sericea
lespedeza research have been to develop a lespedeza low in tannin
and to increase nematode resistance. Until recently, the stan-
dard cultivars of sericea lespedeza were 'Arlington', 'Serala',
and 'Interstate'. Serala and Interstate were released by the
Auburn University Agricultural Experiment Station in 1962 and
1969 (Donnelly 1965b and 1971) . In 1978, three cultivars were
released. 'Serala 76' and 'Interstate 76' released by the
Alabama and Georgia Agricultural Experiment Stations and the
U.S. Department of Agriculture contained nematode resistance and
other improvements not in the original cultivars (Donnelly and
Minton 1979). 'Appalow' , the first prostrate lespedeza, was
released by the Kentucky Agricultural Experiment Station and
the U.S. Department of Agriculture (Henry and Taylor 1981). In
1980, 'AU Lotan' was released by Dr. E. D. Donnelly of the
Alabama Agricultural Experiment Station (Donnelly 1981) . This
cultivar is low in tannin content and has greater nematode re-
sistance than previous sericea lespedeza cultivars.

LUPINE

Lupine species that are under evaluation in the Southeast are
blue lupine (Lupinus angus tifolius L.), white lupine (L. albus
L.), and bicolor lupine (L^. hispanicus spp. bicolor , Merino,

J. S. Gladstones). The objectives of lupine improvement are
to reduce the alkaloid content, increase seed shattering resis-
tance, and increase winterhardiness. Georgia and Louisiana are
involved in lupine improvement. A number of recent cultivar
and germplasm releases have been made by Dr. John D. Miller,

Dr. Homer D. Wells, and others of the U.S. Department of Agri-
culture and the Georgia Agricultural Experiment Station.

The standard cultivars of blue lupine have been 'Richey' ,

'Borre' , 'Rancher', 'Blanco', and 'Frost'. Blanco and Rancher
were released by the Georgia Agricultural Experiment Station
and the U.S. Department of Agriculture in 1960 (Forbes et al.

1964 and Forbes and Wells 1967) . Frost was released by the
Georgia and Florida Agricultural Experiment Stations and the U.S.
Department of Agriculture (Wells et al. 1980a) . This cultivar
showed more seed-shattering resistance than previous cultivars.
Also, Georgia and the U.S. Department of Agriculture released a

51

winterhardy germplasm, WH-1, of blue lupine in 1980 (Wells and
Miller 1981) .

The standard cultivar of white lupine was ’Hope' released by the
Arkansas Agricultural Experiment Station in 1970 (Offutt 1971) .
In 1980, the Georgia Agricultural Experiment Station and the
U.S. Department of Agriculture released ' Tifwhite-78 ' white
lupine, which has a low alkaloid content, improved winter-
hardiness, and decreased seed shattering (Wells et al. 1980b).

In 1982, a bicolor lupine germplasm, Bicolor-1, was released by
the Georgia Agricultural Experiment Station and the U.S. Depart-
ment of Agriculture (Miller and Wells 1983a) .

BIRDSFOOT TREFOIL

Interest in birdsfoot trefoil, Lotus corniculatus L., has in-
creased in the South. New releases are being considered in
Alabama and Georgia. Kentucky recently released the cultivar
’Fergus'. These cultivars have been developed for 1) improved
forage yield, 2) improved seed yield, 3) improved persistence,
and 4) improved pest resistance. ’AT-P’ birdsfoot trefoil will
be released by the Alabama Agricultural Experiment Station if
adequate seed production can be obtained.

OTHER LEGUMES

Many other legume species are involved in selection and improve-
ment programs in the Southeastern U.S. Though not all of the
species can be covered in this paper, some of the recent and
forthcoming releases will be cited. The Alabama Agricultural
Experiment Station is planning germplasm releases of T_.
purpureum and T_. mutabile . The Georgia Agricultural Experiment
Station and the U.S. Department of Agriculture released Tift-1
hyacinth bean (Lablab purpureus (L.) Sweet) germplasm in 1982
(Miller and Wells 1983b) and Tifhardy-1 Desmodium canum (J. F.
Gmel.) Schinz and Thell. germplasm in 1981 (Miller and Wells
1981) . The Florida Agricultural Experiment Station released
’Florida’ Desmodium heterocarpon (L.) DC. in 1979 (Kretschmer
et al. 1982). The Kentucky Agricultural Experiment Station re-
leased KY M-l zigzag clover (Trifolium medium L.) germplasm in
1982 (Taylor et al. 1982).

In Florida, Dr. A. E. Kretschmer has an extensive evaluation
program involving over 4,000 accessions of tropical legumes.

Some of the tropical legumes are being evaluated at the Iberia
Livestock Experiment Station in Louisiana by Dr. C. C. Shock.
Although some of these species may be adapted and contribute to
forage systems in the tropical part of the region, their use
over much of the region will be limited by climatic conditions.

This paper covers primarily the public improvement programs for
legume species other than alfalfa. However, the contribution
of industry to the development, promotion, and distribution of

52

legume cultivars should be recognized. Private industry has been
actively involved in red clover improvement with the release of
many cultivars, including 'Florie' by Northrup King and Company,
’Redland II’ by North American Plant Breeders, and 'Redman' by
FFR Cooperative (Buker et al. 1979) . 'Arcadia' is an improved
ladino clover distributed by Northrup King and Company. Cal/

West Seeds has a white clover improvement program with several
experimentals in the regional evaluation test. The Louisiana
Seed Company has increased and distributed four proprietary
cultivars from the Alabama vetch breeding program (i.e., Vantage,
Cahaba White, Nova II, and Vanguard) as well as Tibbee and Chief
crimson clovers released by the U.S. Department of Agriculture
and the Mississippi Station.

A wide range of diverse legume germplasm is available for gen-
eral and for special purpose use in the Southeastern U.S. How-
ever, the large number of species involved will increase the
breeder's challenge to provide the public with improved legume
germplasm resources in the future.

REFERENCES

Baxter, L. W. , and Gibson, P. B.

1959. Effect of root knot nematodes on the persistence of
white clover. Agron. J. 51:603-604.

Beaty, E. T.; Powell, J. D.; and Young, W. C.

1965. Amclo arrowleaf clover. Crop Sci. 5:284.

Buker, R. J.; Baluch, S. J.; and Sellers, P. A.

1979. Registration of Redman red clover. Crop Sci. 19:928.
Chou, Meei-chih, and Gibson, P. B.

1968. Cross compatibility of Trifolium nigrescens with

diploid and tetraploid Trifolium occidentale . Crop
Sci. 8:266-267.

Donnelly, E. D.

1965a. Registration of Warrior vetch. Crop Sci. 5:605.
1965b. Serala sericea. Crop Sci. 5:605.

1971. Registration of Interstate sericea lespedeza. Crop
Sci. 11:601-602.

1979. Registration of Cahaba White, Vantage, Nova II, and
Vanguard vetch. Crop Sci. 19:414.

1981. Registration of AU Lotan sericea lespedeza. Crop
Sci. 21:474.

Donnelly, E. D., and Minton, N. A.

1979. Registration of Serala 76 and Interstate 76 sericea
lespedeza. Crop Sci. 19:929.

Forbes, Ian, Jr.; Burton, Glenn W. ; and Wells, Homer D.

1964. Registration of Blanco blue lupine. Crop Sci. 4:448.
Forbes, Ian, and Wells, Homer D.

1967. Registration of Rancher blue lupine. Crop Sci. 7:278.
Forbes, Ian; Wells, H. D. ; Edwardson, J. R. ; Burns, R. E.; and
Dobson, J. W.

1970. Registration of Frost blue lupine. Crop Sci. 10:726.

53

Gibson, P.
1973.

Gibson, P.

J. T.

1971.

Gibson, P.
1969.

Gibson, P.

1969.

Gibson, P.
1975.

Henry , D . S
1981.

Hollowell,

1951.

1953.

1958.

1960.

Hoveland, C
1967.

Johnson, W.

1970.

B.

Registration of SC-1 white clover germplasm. Crop
Sci. 13:131.

B.; Barnett, 0. W. ; Chen, Chi-Chang; and Gillingham,

Interspecific hybridization of Trifolium unif lorum
L. with T”. occidentale D. Coombe and with _T. repens
L. Proc. Assn, of So. Agric. Workers. (Abstr.)
Feb. 1-3, Jacksonville, Fla.

B., and Beinhart, G.

Hybridization of Trifolium occidentale with two
other species of clover. J. Hered. 60(2): 93-96.

B.; Beinhart, George; and Halpin, J. E.

Registration of Tillman white clover. Crop Sci. 9:
522.

B., and Chen, Chi-Chang.

Registration of SC-2 and SC-3 clover germplasms.
Crop Sci. 15:605-606.

. , and Taylor, N. L .

Registration of ’Appalow' sericea lespedeza. Crop
Sci. 21:144.

E. A.

Registration of varieties and strains of red clover
II. Agron. J. 43:242.

Registration of varieties and strains of crimson
clover, I. Agron. J. 45:318-320.

Registration of varieties and strains of white
clover (T. repens) . Agron. J. 50:692.

Registration of varieties and strains of crimson
clover, II. Agron. J. 52:407.

. S.

Registration of Yuchi arrowleaf clover. Crop Sci.
7:80.

C. ; Donnelly, E. D.; and Gibson, P. B.
Registration of Regal white clover. Crop Sci.
10:208.

Knight, W. E.

1972. Registration of Tibbee crimson clover. Crop Sci.
12:126.

Knight, W. E.; Ahlrich, V. E; and Byrd, Morris.

1969. Registration of Meechee arrowleaf clover. Crop Sci
9:393.

Kretschmer, A. E., Jr.; Brolmann, J. B.; Snyder, G. H.; and
Coleman, S. W.

1982. Registration of ’Florida’ carpon desmodium. Crop
Sci. 22:158-159.

Massey, J. G.

1966. Preliminary evaluations of some introductions of
Persian clover (Trifolium resupinatum L.). Ga.
Agric. Exp. Stn. Bull. (N.S.) 180, 14 pp.

Miller, John D., and Wells, Homer D.

1981. Registration of Tifhardy-1 Desmodium canum germ-
plasm. Crop Sci. 21:476.

54

1983a. Registration of Bicolor-1 lupine germplasm. Crop
Sci. 23:189.

1983b. Registration of Tift-1 hyacinth bean germplasm.
Crop Sci. 23:190-191.

Nichols, R. L.; Minton, N. A.; Knight, W. E.; and Moore, W. F.
1981. Meloidoyne incognita on arrowleaf clover. Nemo-
tropica ll:No. 2. 191-192.

Offutt, M. S.

1971. Registration of Hope white lupine. Crop Sci. 11:
602.

Taylor N. L.

1979.

1982.

Taylor, N.
1973.

Taylor, N.
1982.

Taylor, N.
1978a.

1978b.

Templeton,

1975.

Weihing, R.

Registration of red clover introduction bulk germ-
plasm. Crop Sci. 19:564.

Registration of gene marker germplasm for red
clover. Crop Sci. 22:1269.

L., and Anderson, M. K.

Registration of Kenstar red clover. Crop Sci. 13:
772.

L.; Cornelius, P. L.; and Sigafus, R. E.

Registration of KY M-l zigzag clover germplasm.

Crop Sci. 22:1278-1279.

L., and Quesenberry, K. H.

Registration of Trifolium medium x T^. sarosiense
hybrid germplasm. Crop Sci. 18:1102.

Registration of Trifolium sarosiense x 4X _T.
alpestre hybrid germplasm. Crop Sci. 18:1102.

W. E., Jr., and Taylor, N» L.

Performance of bigflower vetch seeded into bermuda-
grass and tall fescue swards. Agron. J. 67:709-712.
M.

1962. Selecting persian clover for hard seed. Crop Sci.

2:381-382.

Wells, Homer, D. ; Forbes, Ian, Jr.; Burns, Robert; and Miller,
John D.

1980a. Registration of Tifblue-78 blue lupine. Crop Sci.
20:824.

Wells, Homer D.; Forbes, Ian; Burns, Robert; Miller, John D.;
and Dobson, Jim.

1980b. Registration of Tifwhite-78 white lupine. Crop Sci.
20:824.

Wells, Homer D. , and Miller, John D.

1981. Registration of WH-1 blue lupine germplasm. Crop
Sci. 21:992.

55

Forage Plant Resources

FORAGE ATTRIBUTES FOR IMPROVED ANIMAL PERFORMANCE
H . Lippke

Texas Agricultural Experiment Station

Most forage species will provide at least moderate levels of
nutrition to ruminants during brief periods of the growing sea-
son. The objective of breeding and management research is to
improve those characteristics that will increase both rate of
animal production and the length of time when a high rate of
production can be achieved. Of the six classes of nutrients
required in balanced supply by animals, carbohydrates and pro-
teins are of major economic concern for forage diets. Minerals,
vitamins, and water can be supplemented at relatively low cost.
Essential lipids, like the B vitamins, appear to be provided by
rumen microorganisms in sufficient quantity to all but the
youngest ruminants. Attention, therefore, centers on the sup-
ply of energy-yielding compounds, primarily carbohydrates, and
nitrogenous compounds, primarily protein, and the influence of
plant structure on their concentration and availability.

The work of Weston and Hogan (1968) indicates that the concen-
tration of dietary protein needed by rumen microorganisms for
maximum rumen function may be as low as 6%, a value much lower
than that needed by the host animal when producing at even mod-
erate levels. In the great majority of forages, however, it is
energy availability and not protein that first limits animal
performance. The exceptions include stored forages having a
high grain content .

Figure 1 outlines the characteristics of plant structure that
bear upon digestible energy intake. Rate of fermentation in
the rumen and rate of passage of undigested residues from the
rumen regulate intake through their effect on chemical satiety
and gut fill (Ellis, 1978; Forbes, 1980; Lippke, 1980). Extent
of digestion has its obvious effect on gut fill and, therefore,
on intake. The relationships between extent of digestion and
rate of fermentation or rate of passage are usually positive.
When plant structure is such that normal processing (i.e.,
grazing and chewing) results in smaller particles, rate of
fermentation increases more than rate of passage and extent of

56

INTAKE EXTENT OF DIGESTION

57

digestion increases. Mechanical grinding, on the other hand,
commonly increases rate of passage more than rate of fermenta-
tion, and extent of digestion declines (Hogan and Weston, 1967).

Rate of fermentation is strongly influenced by the proportion
of soluble carbohydrates in forages and the composition of
structural carbohydrates, also called cell wall constituents
(CWC) . Fermentation of neutral detergent solubles is very
rapid (Gray et al., 1967) and almost complete (Van Soest, 1967).
CWC, represented analytically by neutral detergent fiber (NDF)
(Van Soest and Wine, 1967), have a much slower fermentation
rate that is influenced primarily by the degree of structural
fragility and, hence, particle size (Laredo and Minson, 1973).
Paradoxically, rate of fermentation of solubles can sometimes
be too fast, as with very immature ryegrass, resulting in a
disruption of rumen function, and severely reduced intake
(Lippke, 1982). A minimum of about 10% indigestible fiber
appears to be needed in the diet for maximum digestible energy
intake (Lippke, 1982), presumably to help buffer the rapid
release of acids that accompany a high fermentation rate (Van
Soest , 1982) .

The structural components of forages appear to be fermented at
variable rates. Akin and Burdick (1975) reported that both
mesophyll and phloem tissues were rapidly and totally degraded
by in vitro rumen fermentation within 12 hr while outer bundle-
sheath cells and noncutinized portions of epidermis were de-
graded more slowly. Sclerenchyma and lignified vascular tissue
were not degraded. Akin et al. (1975) also reported that acid
detergent removed approximately the same tissues from Coastal
bermudagrass leaves as did in vitro fermentation. These obser-
vations agree with the report by Lippke (1980) indicating a
high positive correlation between hemicellulose : cellulose and
NDF intake, where hemicellulose = (NDF - ADF) . A higher pro-
portion of rapidly digested fiber, as indicated by a higher
hemicellulose : cellulose ratio, should correlate well with in-
creased rate of passage from the rumen and increased NDF intaka

The polyphenolic polymers, commonly referred to as lignin,
within the plant cell wall appear to be responsible for the
limitation of intake of most forages, both by their effect on
extent of digestion and on fragility. Lignin has commonly been
thought to exert its inhibitory action by preventing the
physical attachment of rumen bacteria to the cell wall
(Dehority and Johnson, 1961). Alternatively, Bacon (1979) has
suggested that the structure of indigestible fiber is composed
of a highly substituted polysaccharide chain having covalent
linkages to lignin and that digestive enzymes cannot proceed
past such linkages along the chain. Work is underway now to
determine whether or not lignin has an inhibitory action on
rumen microorganisms independent of its direct effect on utili-
zation of plant fiber (D.E. Akin, personal communication).

58

The "ideal" forage for high animal performance can be summariz-
ed as having 34% neutral detergent solubles (half of that pro-
tein) , 54% potentially digestible fiber having a fermentation
rate of .4 hr-1, and 12% indigestible fiber, which includes 3%
lignin. For warm-season grasses, significant progress toward
this ideal can be made by bringing NDF down to 60% and then
selecting for increased mesophyll and phloem within the struc-
tural carbohydrates. Some improvements might also be made in
many cool-season species by increasing NDF while reducing lig-
nin. Researchers in forage improvement should be encouraged by
the substantial gains in animal performance that can be achiev-
ed with relatively small changes in structure of most forage
species .

While not included in this paper, such agronomic factors as

growth habit and persistence under grazing are regarded as

being at least of equal importance to those topics discussed.

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.

Akin, D. E., and Burdick, D.

1975. Percentage of tissue types in tropical and temper-
ate grass leaf blades and degradation of tissues by
rumen microorganisms. Crop Sci. 15:661.

Bacon, J. S. D.

1979. Plant cell wall digestibility and chemical struc-
ture. Studies in Anim. Nutr. and Allied Sciences.
Rowett Research Institute. 35:99.

Dehor ity, A., and Johnson, R.

1961. Effect of particle size upon the in vitro cellulose
digestibility of forages by rumen bacteria. J.
Dairy Sci. 44:2242.

Ellis, W. C.

1978. Determinants of grazed forage intake and digesti-
bility. J. Dairy Sci. 61:1828.

Forbes, J. M.

1980. A model of the short-term control of feeding in the
ruminant: Effect of changing animal or feed
characteristics. Appetite 1:21.

Gray, F. V.; Weller, R. A.; Pilgrim, A. F.: and Jones, G. B.

1967. Rates of production of volatile fatty acids in the
rumen. V. Evaluation of fodders in terms of
volatile fatty acid produced in the rumen of sheep.
Aust. J. Agric. Res. 18:625-634.

59

Hogan, J.
1967.

Laredo, M.
1973.

Lippke, H.
1980.

Lippke, H.
1982.

Van Soest,
1967.

Van Soest,
1982.

Van Soest,
1967.

Weston, R.
1968.

P., and Weston, R. H.

The digestion of chopped and ground roughages by
sheep. II. The digestion of nitrogen and some
carbohydrate fractions in the stomach and intes-
tines. Aust. J. Agric. Res. 18:803-819.

A., and Minson, D. J.

The voluntary intake, digestibility, and retention
time by sheep of leaf and stem fractions of five
grasses. Aust. J. Agric. Res. 24:875-888.

Forage characteristics related to intake, digesti-
bility and gain by ruminants. J. Anim. Sci.
50:952.

Indigestible fiber and diet selection by yearling
cattle. Tex. Agric. Expt. Sta. PR-3949.

P. J.

Development of a comprehensive system of feed
analysis and its application to forages. J. Anim.
Sci. 26:119.

Peter J.

Nutritional Ecology of the Ruminant . 0 & B Books,

Inc., Corvallis, Oregon, p. 38.

P. J., and Wine, R. H.

Use of detergents in the analysis of fibrous feeds
IV. Determination of plant cell-wall constituents
J. Assoc. Official Anal. Chem. 50:50.

H., and Hogan, J. P.

Factors limiting the intake of feed by sheep. IV.
The intake and digestion of mature ryegrass. Aust
J. Agr. Res. 19:567.

60

Panel Discussion: Data Required Before Releasing Forages.
What Kind and How Much?

THE NEED FOR ANIMAL TRIALS

D. A. Sleper and F. A. Martz, University of Missouri,
and A. G. Matches and J. R. Forwood,

U.S. Department of Agriculture

One of the limitations in many forage breeding programs is the
inability to identify, during the course of cultivar develop-
ment, plant materials that would lead to improved animal pro-
ductivity • Many forage breeding programs simply do not have
the resources to evaluate selected materials with animals.

Those forage improvement programs that have the resources for
animal evaluation will often use animal evaluation as a last
step prior to release. It is desirable to have animal perfor-
mance data prior to release of the new cultivar.

PHASES OF EVALUATION

At the University of Missouri, we have made a commitment to
evaluate new tall fescue and orchardgrass synthetics with graz-
ing animals prior to release. The forage grass breeding pro-
cedure is directed into several phases :

Phase I. Plant introduction. Plants are obtained from various
sources such as plant introduction stations, plant breeders,
local collections, crosses, and cultivars.

Phase II. Identify desirable traits and genetic variability.

Objectives of what trait (s) is (are) desirable in the new cul-
tivar is (are) established. The amount and kind of genetic
variability is determined to make an intelligent decision re-
garding the choice of the breeding procedure to incorporate the
traits .

Phase III. Plant development. The breeding procedure selected
is used to improve the trait (s) chosen in Phase II. The new
synthetic (s) is (are) developed.

Phase IV. Small plot evaluation. During this phase we can
determine what the influence of environmental variables such as
fertility, locations, weather, insects, diseases, management.

61

compatibility with legumes, etc., have on the new synthetics.

If more than one synthetic is evaluated, the best ones are
chosen for animal evaluation trials.

Phase V. Seed increase. It is necessary to increase the
amount of seed of the new synthetic so that grazing trials can
be established.

Phase VI. Animal evaluation. Animal performance is used to
evaluate the new synthetic (s) . At the University of Missouri,
animal performance is usually evaluated with grazing trials and
in some instances feeding trials with hay.

Phase VII. Release and increase of seed.

Do all potential forage cultivars need to have animal data prior
to release? The answer to this question is not immediately
apparent. For example, one might conclude in developing a cul-
tivar for only higher seed yields that animal evaluation may
not be necessary. This is a dangerous assumption since the
breeder may not be aware of changes in plant composition such
as antiquality factors, mineral concentrations, etc., that
may have an influence on animal performance. Also, if resis-
tance for pathogens and insects is bred into a cultivar, the
factors responsible for conditioning this resistance may also
influence animal performance. For example, phenolic compounds
have been reported to be synthesized by the host in response to
fungal infection (Swain et al., 1979) and have been reported to
be antibacterial agents. It is conceivable that these antibac-
terial agents could influence animal performance. Certainly,
if the breeding objective for a cultivar is the improvement of
a particular quality parameter, animal performance data are
essential .

ANIMAL EVALUATION TRIALS WITH TALL FESCUE

Under grazing, differences in animal gain among forage treat-
ments are a function of the amount of herbage available, its
nutritive value, and the amount consumed by animals (Matches
et al. , 1983) . To evaluate the forage quality of potential
cultivars, herbage allowance per animal must be uniform among
all treatments.

A grazing experiment was initiated in 1974 to compare a new
University of Missouri tall fescue synthetic (experimental
1-96 and later released as 'Missouri-96') with four other tall
fescue strains. The primary objectives of the experiment were
to determine if differences in animal performance could be de-
tected among tall fescue synthetics using relatively small pas-
tures, and to identify factors associated with differences in
animal performance.

Five tall fescue synthetics, namely ' Kentucky- 31 ' , 'Kenmont',
'Fawn', 'Kenhy', and Missouri-96, were seeded into 0.47-ha pas-

62

tures at the University of Missouri's Southwest Research Center.
The experimental design was a randomized complete block with
three replications.

Hereford heifers which averaged 225 and 204 kg live weight at
the start of grazing in 1974 and 1975, respectively, were used
as testers. Grazing periods were approximately of 40 days' dur-
ation each for separate evaluations during the spring, summer,
and fall. Pastures were grazed by three tester animals in the
spring and fall and by two testers during the summer. Individ-
ual testers grazed the same cultivar all season, and between
periods of evaluation, they grazed the same cultivar in a re-
serve pasture.

All pastures were strip grazed and stocked at the same grazing
pressure. Therefore, the amount of herbage allowance was equaL
The same herbage allowance was maintained by adjusting with
electrical fences the area grazed dependent upon the amount of
herbage available. The animals were allowed to graze each
strip 7-10 days. Cattle were alloted (disregarding sward
growth) a daily amount of herbage dry matter equivalent to 2.5%
of their body weight. Weekly pasture samplings recorded the
amount of herbage available before grazing and the amount of
residue herbage remaining after grazing. No grain was fed in
these pastures, but mineral and salt were available.

Significant differences were found (P < 0.05) in heifer average
daily gains (ADG) among cultivars in the spring and fall for
both years (Table 1) . However, no significant differences were
detected among cultivars for the summer period. The ADG's on
Kenhy and MO-96 were over 40% greater than ADG on Ky-31 which
is the cultivar most commonly grown in the southern corn belt.
Herbage yield was significantly different (P < 0.05) among cul-
tivars on a per ha basis in the spring and fall, but not during
the summer.

Table 1. — Mean average daily gain (ADG) of heifers and estimated
herbage intake on tall fescue cultivars in 1975-76

„ Spring Summer Fall

Cultivar - —

ADG Intake ADG Intake ADG Intake

kg/day

Kenhy

0.74

3.95

0.34

5.88

0.65

6.06

Kenmont

0.50

4.02

0.27

5.54

0.44

5.95

MO- 9 6

0.71

4.04

0.24

6.00

0.62

5.75

Fawn

0.48

4.11

0.30

5.68

0.45

5.90

Ky-31

0.51

3.96

0.18

5.54

0.45

5.76

Significance

"k : k

ns

ns

ns

*

ns

Std. error

0.04

0.14

0.05

0.13

0.06

0.17

*, ** Significant at the 5 and 1% level of probability,
respectively.

63

Intake was estimated by the difference between the herbage
available at the start of grazing less the amount of residue
remaining after grazing. In no case were there differences
(P <0.05) for intake among cultivars, and correlations between
ADG and intake were low (r = 0.11 to 0.57) . Weekly sward meas-
urements confirmed that there were no differences among culti-
vars for rate of growth.

We do not know for certain why Kenhy and MO-96 have given su-
perior ADG's. Quality analysis has shown in most cases that
in vitro dry matter digestibility (IVDMD) is about the same for
all cultivars tested. Occasionally, Kenhy will have higher
IVDMD than Ky-31 or MO-96; however, it usually is not statisti-
cally significant. Neutral detergent fiber, acid detergent
fiber, hemicellulose, lignin, cellulose, ash, and silica deter-
minations have given little insight as well in explaining the
ADG differences. Intake studies using hay showed slight in-
creases for MO-96 as compared to Kenhy, Fawn, Kenmont, and Ky-
31 (Martz et al. , 1975).

ANIMAL EVALUATION TRIALS WITH ORCHARDGRASS

Two orchardgrass synthetics selected for general resistance to
the stem rust pathogen Puccinia graminis Pers. f . sp. dactyli-
dis Guyot de Massinot were evaluated in replicated grazing
trials similar to what was described for tall fescue earlier.
The grazing trial was conducted in the fall of 1982 and lasted
42 days. Average daily gains ranged from 0.68 to 1.02 kg/day
(Table 2). MO-I and MO-II had the highest ADG's and gains/ha.
The coefficient of variation for both ADG and gain/ha was 10.4%.

Histological studies conducted by Edwards et al. (1981) may ex-
plain the differences in ADG of the orchardgrass synthetics.
Figure 1 contains the cross section of an orchardgrass leaf
blade infected by ]?. graminis . The cross section was stained

Table 2. — Mean average daily gains (ADG) initial weights, final
weights and gain/ha of steers on orchardgrass synthetics
evaluated in the fall of 1982

Synthetics74

Measurement

MO-I

MO-II Hallmark

Potomac

Sterling

Initial weight

(kg)

Final weight

209 a

209 a

204 a

209 a

208 a

(kg)

250 a

252 a

240 ab

244 ab

237 b

ADG (kg/day)

0.98 ab

1.02 a

0.85 abc

0.83 be

0.68 c

Gain/ha (kg)

310 ab

325 a

268 abc

268 abc

212 c

Numbers followed by the same letter are not significantly
different at the 0.05 level as evaluated by the Duncan's
Multiple Range Test.

64

Fig. 1. — Cross section through a pustule of P_. graminis f. sp.
in an undigested orchardgrass leaf blade.

in saf ranin-fast green. Urediospores showed a positive stain-
ing for lignin and easily identified the underlying plant
tissues in which mycelium occurred. The epidermal layer had
ruptured during sporulation and was separated intact from the
underlying mesophyll cells. When the infected tissue was placed
in rumen fluid and later examined histologically, there was
a lack in the amount of tissue digested as compared to the
non-inf ected control (Fig. 2) . The lack of digestion was not
limited to tissues adjacent to uredia, but could be observed in
tissues some distance away. This gives good evidence that this
infected tissue is not digested and one may speculate that this
would give lower animal performance.

It appears that the magnitude of ADG can be attributed to the
level of infection by P_. graminis . MO-I and MO-II had the
least amount of infection while Sterling had the most.

In summary, animal trials are necessary before the release of
forage grass cultivars. The kind and amount of animal data
depends upon the species and upon the objectives for releasing
a cultivar. Our objective was to release a cultivar with im-
proved forage quality. Therefore, conducting grazing trials
where the grazing pressure was constant was essential. We also
feel that more than one location is desirable and that grazing
experiments should be conducted for 2 or 3 years.

65

REFERENCES

Edwards, M. T. , Sleper, D. A., and Loegering, W. Q.

1981. Histology of healthy and diseased orchardgrass
leaves subjected to digestion in rumen fluids.

Crop Sci. 21:341-343.

Martz, F. A., Bell, S. , Mitchell, M. , Matches, A. G. , and

Sleper, D. A.

1975. Advanced fescue evaluation studies--a team research
project. p. 12-17. University of Missouri South-
west Research Center Report 177, University of
Missouri, Columbia, MO.

Matches, A. G. , Martz, F. A., Sleper, D. A., and Belyea, R. L.

1983. Grazing techniques for evaluating quality of forage
cultivars in small pastures, p. 514-516. Proc.

XIV Inter. Grassld. Congr. , Lexington, KY.

Swain, T. , Haeborne, J. B. , and Van Sumere, C. F.

1979. Biochemistry of plant phenolics. In F. A. Lowens
and V. C. Runeckles (ed. ) . Recent advances in
phytochemistry. Vol. 12. Plenum Press, New York.

Fig. 2. Cross section through a pustule of IP. graminis f. sp.
dactylis in an orchardgrass leaf blade after 48 hours of
digestion. Note lack of digestion in area associated
with the infection.

66

Panel Discussion; Data Required Before Releasing Forages.

What Kind and How Much?

USDA’S PRACTICE AT TIFTON, GA.

Glenn W. Burton and Warren G. Monson
U.S. Department of Agriculture

At Tifton we have usually required a new cultivar to be equal
to those in use in most traits and superior in one or more
important traits such as yield or quality. This requires that
selectionswith potential must be compared in various tests
with checks of known performance. Their breeding behavior
must be known. Such selections must be tested in the same
form as the cultivar will be when it reaches the farm. For
example, a 4-clone synthetic should not be tested in the Syn-1
generation unless like Gahi 1 pearl millet it can reach the
farm in the Syn-1.

Information relative to a known check that we like to have
about a selection before it is released as a cultivar may be
outlined as follows:

1. Area of adaptation

2. Dependability

3. Ease of establishment

4. Persistence when utilized for hay or pasture

5. Pest resistance

6 . Management requirements

7. Yield of dry matter and cow matter

8. Quality (palatability and digestibility)

Selecting the top forage requires precise effective screens
for forage and seed yield, cold and drought tolerance, and
disease and insect resistance. Estimates of forage quality
that correlate well with animal performance are needed and
have been supplied in our work with Monson’ s IVDMD test. We
believe some grazing experience is desirable for every new
cultivar that differs appreciably from a known check. Grazing
experiments can supply this experience and may give differences
that are statistically significant if they are large enough.
Release of new cultivars should not be held up until complete

67

adaptation information is available but enough information
relative to a check of known performance should be obtained to
suggest where a new cultivar can be successfully grown.

Because potential new cultivars are frequently little better
than those in current use and because the breeder's greatest
asset, his credibility, is at stake when a new cultivar is
released, he must do everything possible to improve the preci-
sion of his experimental tests. Soil heterogeneity in a test
field can nullify the results of any cultivar evaluation test.
To avoid this problem such tests should be placed in uniform
fields based on uniform crop performance.

We have found that uniform pre- cropping with legumes such as
velvet beans or soybeans for grass tests and with grasses such
as pearl millet or small grains for legume tests is good prac-
tice. Perfect stands of the precrops is a must - otherwise
they can do more harm than good.

We have found that methyl bromide fumigation is a good practice
for spaced plant and small plot tests. It is expensive! Com-
mercial application at Tifton is costing $1,000 per acre in
1983. However, it eliminates practically all weeds and
greatly reduces soil borne pests. The reduced weeding costs
probably cover most of the fumigation cost. More important,
however, is the fact that fumigation makes the soil environ-
ment more uniform, permits rapid establishment of seeded plots
and makes first year results meaningful. The year saved pays
big dividends on the investment.

Machine fertilization can be more uniform than hand applica-
tion if the best machines available are used properly.

We have found that lattice square designs can increase the
precision of some yield trials a great deal. The 9x9
balanced lattice square test that we have used for testing the
yield potential of experimental pearl millet hybrids has on
the average doubled the precision of our tests. With the com-
puter analysis of the data, such tests involve no more work on
the part of the breeder than randomized block experiments.

Increased yield of animal product is usually the bottom line
in any forage breeding program. Increased pest resistance, if
significant, must ultimately result in increased yield of cow
matter and probably dry matter. If yield can be increased in
the presence of the pests, the higher yielding plants will
probably be more resistant if the pests are affecting yield
appreciably. The forage breeder must, therefore, continually
search for new and better screens for forage yield.

Usually spaced plants with no replication must be screened
first. This is the screen that must identify the top few
plants in a population. Improving the uniformity of every

68

step from the seed to the field will pay dividends. We have
our best technician transplant every seedling from flats to
2- inch clay pots. The 2-inch pots set in sand on a greenhouse
bench give each seedling a uniform environment in which to
develop. When large enough to be transplanted without loss of
stand, the plants are removed from the pots and carefully set
in our most uniform fields that have been precropped with
velvet beans and have been uniformly prepared, fertilized, etc.
With all of this and more, it is impossible to select the
highest yielding plant in such plantings. Hopefully, a number
of the highest yielding plants can be selected for replicated
small plot tests.

With our perennial grasses, we have established small plot
tests with clonal material that we usually start in pots in
the greenhouse in the winter. These are then transplanted in
sufficient numbers to small plots to give a coverage of a
2-foot wide strip before the first season is over.

In some of our bahiagrass research, we are interested in com-
paring the performance of different 2-clone hybrids in clipped
plots. To produce enough seed for seeded plots would require
at least one additional year and much extra work. Twelve seed-
lings established in the greenhouse in the winter and set
1-foot apart in the center of a plot will make a sod 2-feet
wide before the season is over. Sixty seedlings of a cross
can give 5 replications and producing so few hybrid seeds is
easy. We have just concluded a 3-year clipping test with 10
entries with seeded plots and potted plant plots side-by-side
with 5 replications. In this test, the potted-plant-plots
established faster, yielded more the first 2 years, and when
correlated with seeded plots gave r values of +.67, +.73, +.83
and +.93 for the 1st, 2nd, 3rd, and 3-year average yields. We
believe such potted-plant-plot tests can be satisfactory for
preliminary screening. Replicated small plot tests from
direct seeding will be preferred at a later date when more
seed is available.

We like the spaced-plant population progress (SPPP) test for
assessing progress made in population improvement such as our
RRPS breeding program with Pensacola bahiagrass. This test as
we have developed it consists of single-spaced-plant plots
replicated 100 times. The test is established from 100 potted
seedlings chosen at random from each cycle of RRPS. The
spaced seedlings are set far enough apart (.9 x .9 m) to per-
mit them to express their yield potential the first year with-
out competition. Yields are taken twice. Two years of using
this test indicate that it maximizes the precision per plant
tested and establishes significant mean differences not evi-
dent in other tests. It also gives the relative estimate of
the genetic variance left in each population, information of
value to the breeder and minimizes the land and resources
required for the test.

69

At Tifton promising spaced plants of b.ahiagrass and bermuda-
grass are tested in replicated small plots for 3 years. Plot
size for bahiagrass is 3 x 16 feet and for bermudagrass is
9 x 16 feet. Tests are replicated 5 or more times. Usually
N at 200 lb/A/yr. + P and K are applied annually. Green
yields are taken from 2 x 14 foot plots with a sickle bar
mower usually 5 times per season. Forage from each plot is
weighed green and is sampled for dry matter percentages. These
samples are later ground and analyzed for IVDMD.

The following outline lists steps that we consider very impor-
tant in measuring forage quality. A failure at any step can
produce misleading results worth less than none at all.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

At Tifton, Georgia, the best entries in clipped plots have
usually been grazed in replicated 2-acre pastures with
150 lbs/N/A/yr. plus P and K for 3 years before release to
certified growers.

Region of adaptation information has been obtained by agrono-
mists in other locations. Outstanding cultivars at Tifton
have usually performed well at similar or warmer latitudes.

Uniform plant growing environment
Uniform management
Uniform age
Representative sam
Uniform drying (70
Active rumen fluid
Precise laboratory procedures
Careful laboratory technicians
Replication

Known performance checks

gling

C) and grinding

70

Panel Discussion: Data Required Before Releasing Forages.

What Kind and How Much?

FORAGE QUALITY ASSESSMENT: IMPORTANT FACTORS FOR PLANT
BREEDERS TO CONSIDER

S. W. Coleman

U.S. Department of Agriculture

INTRODUCTION

The importance of forage quality assessment in plant breeding
and evaluation programs has been readily recognized in the
past decade, although such thoughts may have been somewhat
heretical in the early 1960's (Johnson 1969). Progress has
been made in what is now commonly called "mul tidiscipl ined"
research where agronomists, animal scientists, pest managers
and economists form teams to attack problems.

Hodgson (1981) suggested four questions to be asked concern-
ing breeding and evaluation programs. They are:

(a) the reliability of relatively simple assessment
procedures as predictors of the potential value
of plant material for animal production,

(b) the relevance of the measurements to farming
practice,

(c) the most effective way of incorporating the alterna-
tive procedures into a selection program, and

(d) the resources to be committed to the various
stages .

Selection criteria usually include total production, nutri-
tive value of the forage produced, the ability to establish
easily, to withstand climatic stresses, to adapt to different
management systems, to resist or tolerate pests and diseases,
and to readily produce material for propagation (Burton
1970). A successful breeding program will incorporate many
of the attributes listed above. The complexity clearly il-
lustrates the impossibility of selection on "increased pro-
duction" alone. Certain desirable characteristics are known
to be limiting in certain species, such as digestibility in
most warm-season perennial grasses. Breeding for improvement
of such can improve animal performance. However, concentra-
tion on a particular trait can create its own problems such
as lack of persistence under grazing among more digestible

71

varieties .

The emphasis of this paper involves animal consumption and
utilization of nutrients contained in forages. Though defi-
ciency of any one of the many nutrient factors required by
animals may limit growth, lactation or reproduction to some
degree, energy is the nutrient most frequently found lacking
in forages. Even when deficient, most other nutrients can
usually be easily and economically supplemented.

FORAGE OUALITY

The ultimate assessment of forages is animal production, ei-
ther production per animal or production per unit of land.

The nutritive value of a feed is the product of intake, di-
gestibility and utilization (Raymond 1968). The common for-
ages fed to ruminants have been evaluated much more exten-
sively for energy content, digestibility and even utilization
than for intake (Waldo 1969). Heaney (1969) suggested that
combining digestibility and intake into a single index pro-
vides a means of evaluating the feeding value of forages more
effectively than the evaluation of either alone. This index,
if effective, should be highly correlated with average daily
gain. Data are limited concerning this relationship though a
few trials give reason for optimism (Crampton 1957, Lippke
1980).

When using digestible energy intake (DEI) as an index for
forage quality, the relative contribution of intake and di-
gestibility are not the same. Milford and Minson (1965)
found that digestible dry matter intake (DDMI) of tropical
grasses was more correlated with intake of dry matter than
its digestibility. Crampton et al . (1960) reported that var-
iations in intake accounted for 70 percent of the variability
in the Nutritive Value Index. Crampton (1957), Osbourn et_
al . (1970) and Ventura et aj_. (1975) agreed that intake is

Tfie more important factor in determining quality, but intake
of a given forage is more variable between animals than is
digestibility (Blaxter et al . 1961, Minson et__a]_. 1964, Heany
_et_ _al_. 1968). This variation among animals may be due to (1)
animal weight (Heaney 1969); (2) fatness (Bines et aJL 1969);
(3) physiological rumen volume (Purser and Moir T966 ) ;
and/or (4) retention time of organic matter in the rumen
(Campling et al_. 1961, Hungate 1966). The importance of
voluntary intake however does not imply that digestibility is
not important in determining DEI or other expressions of
quality. Blaxter _et aj_. (1961) calculated that under ad
1 i bi turn feeding conditions, a change in digestibility of DM
from 50 to 55 percent resulted in 100 percent increase in
weight gain.

Much work has been done attempting to relate chemical compo-

72

sit ion of forages to forage quality. Low protein content has
been considered the limiting factor in controlling feed in-
take (Milford and Minson 1965). However, this generally oc-
curs only when crude protein (CP) content of the forage falls
below 6-7% of the DM (Minson and Milford 1967). Above this
"critical level", rumen fill is considered the primary deter-
minant of intake in ruminants (Campling et al . 1961, Conrad
1966) especially with lower quality forages (Fig. 1). When
digestibility reaches 65-70%, then control of intake by rumen
capacity yields to chemostatic or thermostatic controls
(Montgomery and Baumgardt 1965, Blaxter <et aj_. 1961). Since
few forages have digestibilities in this range, we are mostly
concerned with rumen distension or fill.

Montgomery and Baumgardt (1965)

Figure 1. Theoretical relationship between nutritive value
(digestibility) and intake.

73

Basic to the problem of using cell wall constituents (CWC)
to predict forage quality is the fact that CWC, or any other
representative of the fiber portion, fails to manifest itself
as a nutrit ional ly uniform fraction (Lucas et_ al_. 1961). In
general, ideal fractions are either completely digestible or
essentially indigestible (Van Soest 1969). No ideal frac-
tions exist which show a partial digestibility. Perhaps
physico-chemical factors such as encrustation, 1 ignif ication ,
crystal 1 inity of cellulose and the organizational structure
of the forage cell wall fraction will yield some insights in-
to the determination of forage quality. Much attention has
been given to the effects of physical form such as grinding
and pelleting on nutritive value and animal performance.
Excellent reviews have been published by Minson (1963),

Putman and Davis (1961), Beardsley (1964) and Moore (1964).

Several factors other than chemical and/or physical proper-
ties of the plant are involved in forage intake by grazing
animals. Digestible dry matter intake can be quite variable,
especially of warm season or tropical grasses, due to hetero-
geneity of the sward, seasonal production and variation in
sward or canopy structure (Chacon and Stobbs 1976). Rumi-
nants have an enormous task of harvesting 40-60 kg of fresh
feed daily and the special distribution of leaf within the
sward or canopy influences the ease with which the animal can
satisfy its appetite. With leafy temperate pastures, animals
can consume large mouthfuls and can satisfy their appetite
rather easily in 6-8 hrs/day (Stobbs 1973). Cattle graze
warm season pastures for a longer time each day than temper-
ate pastures even when large quantities of herbage are avail-
able for grazing (Stobbs 1974). Time available for grazing
is limited by need for rumination and other factors. Fur-
thermore, rumination time is longer for warm-season forages
than for temperate forages. Thus, the structure of the
sward, especially the verticle leaf density and its ease of
prehension become important factors to consider if the new
release is to be used primarily for grazing.

TECHNIQUES

Reid (1966) in a review discussed the "state of the art" of
forage evaluation. At that time, in vitro fermentation pro-
cedures were gaining acceptance for estimating digestibility
and Van Soest had completed his series of articles describing
chemical fractionation of feeds. No laboratory technique was
available for adequately estimating intake. Now, seventeen
years later, the "state of the art" is approximately the
same. The need to know the parameters previously discussed
makes necessary a screening technique which can be used for
many samples. It must be fast, routine, require very small
amounts of sample and precisely predict the parameter of
i nterest .

74

The cell wall fraction constitutes the structural part of the
plant and is the least digestible and most slowly digestible
portion. Thus, it determines the space-occupying capacity of
a forage or feed (Van Soest 1965), and should afford the
best predictor of intake. Van Soest (1965) reported results
from 82 forages (six plant species) in which intake was cor-
related with various chemical components. Total correlations
over all species showed CWC to be best related (r=.65, P<.01)
to intake. Correlations with intake of all components (lig-
nin, acid-detergent fiber (ADF), protein and cellulose) were
similar within species indicating the uniform influence of
maturity on forage quality. However, between species corre-
lations were more variable. Regression analyses indicated
the relationship between intake and CWC was curvilinear with
the influence of CWC being markedly depressed when CWC con-
stitutes less than 50% of the DM. This suggests that CWC,
representing the total fibrous part of the forage, limited
intake when the proportion of these constituents increased to
more than 55 to 60% of the dry matter. These relationships
are consistent with observations regarding the existence of a
point in the intake-fiber mass relationship where fiber mass
ceases to affect intake (Conrad _et _al_. 1964, Montgomery and
Baumgardt 1965).

Digestibi 1 ity

The recognition of the importance of the digestibility of a
given forage by ruminants led to development of the two-stage
in vitro technique (Tilley and Terry 1963). Application of
this technique has enabled systematic studies of factors in-
fluencing digestibility of forages such as variation between
species and varieties, and estimation of genotypic variation
and heritabil ity. The improved precision and acceptability
of the technique over prediction from chemical analyses
(Table 1) added a whole new realm of selection criteria in
breeding programs. Unfortunately, the technique is not with-
out flaws, some of which are maintenance of a donor animal,
variability in the potency of the rumen inoculum from run to
run, and interactions across some species due to different
digestion rates. The last two can be partially overcome by
donor diet standardization and inclusion of standards of
known in vivo digestibility.

Two techniques have been used which have theoretical advan-
tages over the typical in vitro system. Kapp et_ _al_. (1979)
suggested 1 yoph i 1 i zed rumen fluid as an alternative to fresh-
ly removed inoculum. Their results showed some differences
in digestibility among sorghum grain, corn grain and alfalfa
hay. However, rank in digestibility was not affected by
1 yoph i 1 ization.

Cellulolytic enzymes have also been suggested as digesting

75

Table 1. --Rel ationship of laboratory techniques to digestibility of forage
sampl es

X

c

c

c

c

c:

03

.

o

o

o

o

o

i — 1

, —

to

to

to

to

to

■> — «”

03

c

c:

c

c

c

•

X

z:

2:

s

z:

i —

CD

03

to

X

X

X

X

X

CD

X

c

e

c:

c

c

X

O

to

03

03

03

03

03

CD

c

CD

QJ

O

o '

O

O

O

X

to

i-

on oo

XJ OO

X oo

X oo

x oo

O oo

• r—

cd

cd

CD r-^

CD 0^

CD 0^

CD

X-

4—

c 03

V- 03

V- 03

U- 03

V- 03

X 03

i-

aj

03 i— 1

03 r— 1

03 i— 1

03 X

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76

^Stem only.

bIn vitro dry matter disappearance (Tilley and Terry 1963).

agents. Jarrige et al . (1970), Jones and Hayward (1973), and
McLeod and Minson- 0-978) obtained good correlations between
in vivo and cellulase digestibility though earlier attempts
at using cellulolytic enzymes met with little success
(Donefer et al . 1963). Rees and Minson (1976) observed that
in vitro techniques were biased when used to estimate digest-
ibility of grasses grown with various levels of sulfur ferti-
lizer. Both rumen fluid-pepsin and pepsi n-cel 1 ul ase resulted
in bias. No doubt there are other environmental factors
which may uniquely influence plants in such a way that labor-
atory techniques give biased estimates of animal data. How-
ever, provided researchers are aware that such potentials
exist and insure the procedures are used within the range of
genetic and environmental conditions for which they have been
tested for they can provide ranking as well as estimates of
actual digestibility for forages.

Near infrared reflectance spectroscopy offers a rapid, nonde-
structive technique for estimating chemical and biological
parameters of forage quality, including digestibility. Ex-
tensive work has been conducted to calibrate NIR for chemical
quality estimates of temperate forages (Shenk _et aj_. 1976)
but only limited work has been done with warm-season forages
( Burdick et _al_. 1981, Col eman et aj_. 1982).

Intake

Though the in vitro technique for estimating digestibility
has been wicTely received and used and much progress in quali-
ty of forages has been realized, little has been accomplished
to incorporate an estimate of intake into forage quality as-
sessment. One of the problems of assessing intake is the in-
herent animal variability and bias due to class and status of
the animal. Intake assessment could very well lead to great-
er improvement in warm-season forages than digestibility as-
sessment due to their high fiber, long residence time and
slow rate of digestion as compared to temperate species.

Rate of digestion and rate of passage are important factors
relative to mechanisms which control intake (Waldo et al .
1972), but they are not causative agents. Several efforts
have been made to identify or characterize the causative
agents. Balch (1971), Sudweeks et aj_. (1975) and Welch and
Smith (1969) suggested that rumination time or time spent
chewing was related to fibrousness or coarseness of rough-
ages. Welch and Smith (1969) found a significant correlation
(r = .99) between minutes of rumination time and CWC intake.
These results suggest that some factor other than presently
known chemical fractions influences rumen fill which in turn
influences intake. Lignin content per se probably has little
effect on extent of digestibility, but the amount of ligni-
fied (encrusted) tissue was implicated as being very impor-
tant from microscopic evaluations (Akin _et_ aJL 1974, de la

77

Torrie et_ a]_. 1974). The lack of influence of lignin con-

tent has long been suspected as a result of comparing digest-
ibility of legume vs grass species. The understanding of
physical characteristics of forage plants which influence
rate and extent of digestion, particle size reduction and
rumen clearance rate is necessary to be able to predict in-
take using inexpensive 1 aboratory methods .

Rapid, precise laboratory techniques related to intake are
needed which require only a small sample. A few potential
techniques are listed in Table 2. Small ruminants such as
meadow voles or blue duikers (Cowan et aj_. 1976) have been
proposed to estimate both intake and digestibility. However,
more forage is required (approx. 2 kg) than most plant breed-
ers harvest from individual nurseries. Perhaps one of the
most successful tools to date is a grinder supplied with a
wattage meter to measure the power required to grind a given
amount of the forage in question (Laredo and Minson 1973; D.
I. H. Jones, personal communication). Scientists at the
Welsh Plant Breeding Station routinely used the instrument to
estimate intake of their plant breeding material. An earlier
approach was artificial mastication (Troelson and Bigsby
1964). They found a high correlation (r = .94) between
"particle size index" after mastication and intake/100 lb.
body weight of sheep. Though NIR has potential as a tech-
nique for estimating intake, essentially no data have been
published relating intake to near infrared spectra, due pri-
marily to the difficulty in obtaining sufficient samples of
known intake. One might expect interactions with predict-
ability and forage type similar to those shown by Moore
(1977) when intake and digestibility of tropical forages were
predicted from chemical components using equations from tem-
perate forages.

GRAZING

Hodgson (1981) writes "It would seem to be an article of
faith that any plant material intended for use under grazing
conditions should be selected and tested under such condi-
tions, or at least by procedures which have been shown to
provide a true index of performance under grazing. The com-
parative assessment of pasture plants in terms of animal pro-
duction is a major undertaking, and it is unlikely ever to be
realistic to subject more than a small number of the most
promising genotypes to trials involving practical systems of
animal production".

Grazing produces a very complex situation where several dy-
namic processes interact with one another. The defoliation
and trampling process of the animal influences plant growth
and persistence. Therefore, plants with prostrate growth and
high tiller population are most suitable characteristics for

78

Table 2. --Rel ationship of intake of forage to laboratory analytical techniques

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79

S D = Standard deviation of mean of animal data.
Grazing with total fecal collection.

grazing (Hodgson 1981). However, erect plant types appear to
increase efficiency of harvesting incident light. On the
other side of the coin, plant growth habits and the resulting
vertical distribution of bulk density may influence harvest-
ing efficiency by the animal. Rate and type of plant growth
influence how much is eaten, what is eaten and how much is
trampled (Chacon and Stobbs 1976) whereas each of the above
influence growth rate, tiller production and canopy struc-
ture.

Once the germplasm has passed through several steps and only
a few superior types are left, feeding and/or grazing trials
may be appropriate. Before animal data are collected, the
influence of the grazing animal on the forage in question
should be evaluated in very small plots. Sheep are excellent
animals for this since they graze closer and would put great-
er pressure on persistence, regrowth potential etc... than
would cattle.

In summary, quality evaluation is an important factor before
forages are released. Evaluations can be made in different
ways depending on the "stage" of evaluation progressing from
simple laboratory predictive procedures to full scale feeding
and grazing trials.

REFERENCES

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1974. Comparative degradation of Coastal bermudagrass ,

Coastcross-1 bermudagrass, and Pensacola bahiagrass
by rumen microorganisms revealed by scanning
electron microscopy. Crop Sci. 14:537.

Balch, C. C.

1971. Proposal to use time spent chewing as an index of
the extent to which diets for ruminants possess the
physical property of fibrousness characteristic of
roughages. Brit. J. Nutr. 26:383.

Beardsley, D. W.

1964. Symposium on forage utilization. Nutritive value of
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Bines, J. A., Suzuki, S. and Balch, C. C.

1969. The quantitative significance of long-term

regulation of food intake in the cow. Brit. J.

Nutr. 23:695.

Blaxter, K. L., Wainman, F. W. and Wilson, R. S.

1961. The regulation of food intake by sheep. Anim. Prod.
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Burdick, D. , Barton, F. E., II and Nelson, B. D.

1981. Prediction of bermudagrass composition and

digestibility with a near-infrared multiple filter
spectrophotometer. Agron. J. 73:399.

80

Burton, G. W.

1970. Breeding sub-tropical species for increased animal
production. Proc. 11th Int. Grassl. Congr.,
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Campling, R. C., Freer, M. and Balch, C. C.

196L. Factors affecting the voluntary intake of food by
cows. 2. The relationship between the voluntary
intake of roughages, the amount of digestion in
ret iculo-rumen and the rate of disappearance from
the digestive tract. Brit. J. Nutr. 15:531.

Chacon, E., and Stobbs, T. H.

1976. Influence of progressive defoliation of a grass
sward on the eating behavior of cattle. Aust. J.
Agric. Res. 27:709.

Coleman, S. W., Barton, F. E., II and Meyer, R. D.

1982. Calibration of a near infrared reflectance

spectrometer for prediction of forage quality.

Okl a. Agric. Exp. Sta. Misc. Publ . MP-112: 102
Conrad, H. R.

1966. Symposium on factors influencing the voluntary

intake of herbage by ruminants: physiological and
physical factors limiting feed intake. J. Anim.

Sci. 25:227.

Cowan, R. L., von Ketehodt, H. F. and Liebenberg, L. H. P.
1976. The blue duiker tested as a laboratory

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1957. Interrelations between digestible nutrient and

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Crampton, E. W., Donefer, E. and Lloyd, L. E.

1960. A nutritive value index for forages. J. Anim. Sci.
19:538.

de 1 a Torrie, R. A.

1974. Micro-histological characteristics of three

warm-season grasses in relation to forage quality.
Ph.D. Dissertation. University of Florida.
Gainsville, Florida.

Donefer, E., Niemann, P. J. , Crampton, E. W. and Lloyd, L. E.
1963. Dry matter disappearance by enzyme and aqueous

solutions to predict the nutritive value of forages.
J. Dairy Sci . 46:965.

Heaney, D. P.

1969. Voluntary intake as a component of an index to

forage quality. Proc. Nat. Conf. Forage Qual . Eval .
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Heaney, D. P., Pritchard, G. E. and Pigden, W. J.

1968. Variability in ad libitum forage intakes by sheep.

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Hodgson, J.

1981. Testing and improvement of pasture species. In: F.
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R. E.

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R. R.

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I. H. and Hayward, M. V.

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L.

Forage evaluation. Proc. XII Annual Farm Seed
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Reid, R .
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83

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1975. Effects of concentrate type and level and forage
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Tilley, J. M. A. and Terry, R. A.

1963. A two-stage technique for the in vitro digestion of
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1964. Artificial mastication - a new approach for
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Van Soest, P. J.

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Waldo, D. R., Smith, L. W. and Cox, E. L.

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84

Panel Discussion: Data Required Before Releasing Forages.

What Kind and How Much?

GRAZING MANAGEMENT AND UTILIZATION RESEARCH PRIOR TO RELEASE OF
PASTURE CULTIVARS

Carl S . Hoveland

University of Georgia

To paraphrase Shakespeare, "to cut or not to cut - that is the
question". Plant breeders have commonly evaluated potential
pasture cultivars with various types of mowing machines, often
obtaining little or no grazing data before release of a
cultivar. There is a good reason for bypassing the grazing
animal - it takes time, requires more seed, and is expensive.

This topic was addressed in depth by Australian and USA
scientists in a Forage Evaluation and Utilization Workshop at
Armidale, New South Wales, Australia in October 1980 (Wheeler
and Mochrie) where they "agreed quite clearly" that:

"Forages should not be released for public
use until they have been evaluated with
animals . "

If this rule had been applied to forage cultivars in the past,
many would never have been released. Today, more plant breeders
in public agencies are evaluating their cultivars with animals
but less of this is done in private companies.

Before we make a judgement of the breeders, it is important to
recognize that breeders of forage cultivars have many
objectives :

1. Resistance or tolerance to pests such as nematodes,
insects, or diseases.

2. Seasonal forage distribution such as improved winter
production.

3. Improved nutritive quality. This may include reduced
lignin, reduced alkaloid or tannin levels, and increased
mineral content.

85

4. Tolerance to unkind soil conditions such as high aluminum
or manganese in acid soils, low soil phosphorus, or poor
drainage .

5. Tolerance to livestock trampling.

6. Competition with other species.

Obviously, some of the above items are not directly related to

grazing of livestock. Why then do we need grazing data before

release of forage cultivars?

1. A grazing animal is not the same as a mowing machine.
This may seem so commonly known that it needs not be
mentioned, yet many scientists forget that the grazing
animal has special effects on pasture plants. The grazing
animal exercises selectivity for desirable plant parts
such as leaves and for individual species in a mixed
sward. Grazing animals may tear rather than cut the
herbage. In addition, there is a pulling effect which may
be especially severe on the plant when it is young. The
trampling effect of hooves puts enormous weight on small
areas, compacting the soil and crushing plant parts.
Livestock graze during wet as well as dry weather, causing
pugging of pastures which can be more severe on one plant
species than another. Grazing usually results in frequent
defoliation as contrasted to the mowing machine which
allows periods of recovery between harvests. The frequent
defoliation in a pasture is often most severe during
period of limited growth during winter. Grazing animals
also defecate and urinate on a pasture, something not done
by a mowing machine.

2. Dry matter production over the growing season is not

directly proportional to stock carrying capacity or animal
production produced. Changes in temperature and rainfall
change yield and quality throughout the year. The mowing
machine cannot really evaluate the amount of animal

product produced, even with forage quality evaluation.

3. Anti-quality components of the forage complicate the

picture. Alkaloids in some grasses and lupines reduce
animal performance or make the forage unpalatable. Low
levels of tannin in legumes such as trefoil and arrowleaf
clover reduce bloat potential but high levels of tannin in
sericea lespedeza reduce digestibility of both dry matter
and crude protein. Glucosides in sorghums and fungal
endophytes of tall fescue also may result in reduced

livestock performance. Levels of these components may be

determined in the laboratory but their practical
importance is often modified within the rumen.

86

4. Persistence under grazing and encroachment of other
species can be very different when grazed than mowed. The
amount of leaf tissue removed, effect on root or crown
carbohydrates, and tillering is often quite dissimilar
under grazing and cutting, thus affecting persistence.

5. Seasonal distribution of growth is better evaluated with
animals than with a mowing machine. The lag time required
for harvesting and sudden removal of harvested forage
often interact with weather conditions to affect forage
growth rate.

6. Grazing trials can help "sell" a new cultivar if it really
is superior. Producers are far more impressed with animal
performance than they are with forage yield data from
small plots .

If grazing is to be used in evaluating cultivars, how should

grazing studies be conducted on new cultivars? This is a

complex area and only a few suggestions are offered in this

brief discussion:

1. Animal preference studies are low priority as the grazing

animal's preference rarely has biological significance
when the animal is forced to eat the less preferred
species. Cattle do not like sericea lespedeza, yet when
confined to it, they will perform satisfactorily.

Alfalfa, a top quality forage, may be ignored by cattle
initially when put pastures of this species as they search
out weedy species such or chickweed.

2. Cultivars should be grazed in trials as they would be
under normal farm conditions unless a special grazing
method is to be recommended.

3. Grazing should be done with the kind of animals expected
to be carried by farmers on this pasture cultivar. Sheep
grazing of experimental cultivars may reduce the cost but
results may not easily be transferred to predict cattle
performance and effects of grazing on the cultivar.

4. Comparisons should be made with standard cultivars in
replicated grazing experiments over several years.

5. Observational on-farm grazing trials in cooperation with
extension forage and animal science specialists can be
useful in evaluating persistence, reseeding, and other
characteristics. Also, these trials may be useful in
convincing the extension specialist that the cultivar is
good and should be promoted. This method is commonly used
by private companies as it is low-cost and offers the
advantage of promoting the cultivar.

87

SUMMARY

Do we always need animal grazing data before release of a
pasture cultivar?

1. Cutlivars of species new to the area or from exotic
germplasm quite different from existing cultivars or
selected for improved nutritive quality should always be
subjected to grazing by livestock before release to the
public .

2. It can be argued that there is a lesser need for grazing
data if the new cultivar was selected for pest resistance,
is a well-established pasture species, has no anti-quality
problems, and plant morphology has not been changed. The
danger with this approach is that in selection for one
trait another may have been altered and so affect animal
performance. Thus, grazing of potential cultivars before
release is the safest approach to avoid a potential
problem.

REFERENCE

Wheeler, J.
1981.

L. , and Mochrie, R. D.

Forage evaluation: concepts and techniques.
CSIRO, East Melbroune, Australia and American
Forage and Grassland Council, Lexington, Kentucky.

88

Panel Discussion; Data Required Before Releasing Forages.

What Kind and How Much?

STATE AGRICULTURAL EXPERIMENT STATION POLICIES
W. C. Godley
Clemson University

Dr. Bouton asked that I address the topic "Data Required Before
Releasing Forage Cultivars for Grazing - What Kind and How
Much?", from an experiment station administrator’s viewpoint.
Rather than present only my own thoughts and ideas or the policy
of the South Carolina Agricultural Experiment Station, I chose
to get input from my colleagues in the Southern Region. To
accomplish this, a questionnaire that could be answered in most
cases by a "yes" or "no" was developed. The 15 questions were
designed to get a broad view of the policies and procedures
involved in releasing cultivars, germ plasm and breeding lines.
The questionnaire was mailed to the directors of the agricul-
tural experiment stations in the 13 southeastern states. All
of them responded but due to their particular situations, did
not answer all questions completely. A summary of the infor-
mation obtained from the questionnaire is the basis for my
comments .

Formal policies for release of germplasm exist in all but two
of the southern experiment stations surveyed; only two do not
have a formal policy regarding the release of breeding lines
developed by the experiment station; while all but one have
a formal policy for the release of cultivars. Within the
southern states, however, the policies are implemented a bit
differently. In Arkansas, for example, each release is handled
in a manner consistent with the agricultural experiment station
mission. The kind of germplasm (i.e., plant species) determines
the exact process of release. In Louisiana, release is re-
quested by the plant breeder through the department to the
director. An ad-hoc committee is appointed by the director
to review the data and to make recommendations. If the com-
mittee recommends release, the director prepares a release
statement and appropriate publicity. Oklahoma, on the other
hand, has a rather standard, but unwritten, policy.

Most of the experiment stations have a mechanism for the free
exchange of germplasm in both the private (64%) and public

89

(85%) sectors. Four stations, however, will not freely release
germplasm among breeders in the private sector while two will
not exchange germplasm among breeders in the public sector.

At six stations the free exchange is curtailed in the private
sector and at two stations the exchange is curtailed in the
public sector during some stage of development.

In Alabama, the exchange is curtailed when the line begins
to look very promising and is breeding true for a trait. In
Kentucky, germplasm may be released similar to cultivars but
requirements are less stringent. Louisiana curtails exchange
just prior to release of variety, while Mississippi curtails
the exchange near the level of development suitable for
varietal or germplasm release. In North Carolina, exchanges
with the private sector are made as formal germplasm releases.
Within the public sector, breeders may freely exchange mate-
rial at any stage of development, with their counterparts in
other public agencies. In Oklahoma, free exchange occurs
after official release, except for rare "exclusive" releases.

In Tennessee, advanced breeding lines are not exchanged with
the private sector.

About 80% of the experiment stations have a procedure for the
exchange of cultivars in the private and public sectors. Some
of these procedures, however, are informal.

In testing experimental cultivars before release, all stations
require multiple locations within the state. Half of the
stations require out-of-state tests. All of the stations
require tests over more than one year. Only two states do
not require that the experimental cultivar be tested as a
hay/silage crop; one state does not require simulated grazing
and one state does not require in vitro analyses. All of the
states require reaction to grazing be tested, as well as
animal performance, nutrient analyses, and proximate analyses.

All of the experiment stations have a cultivar release com-
mittee which reviews release proposals and supporting infor-
mation. In determining if the cultivar merits release, all
of the states consider yield, persistence, resistance, area
of adaptation, quality measurement, and undesirable traits.

Only one state does not require a statement of intended use.

One state does not consider a plan for seed or planting stock
increase. Two states do not consider origin, breeding proce-
dure, cultivar description or uniqueness in the decision. All
of the states require superiority over available cultivars
for one or more traits. Only three stations said that they
would release a cultivar that is not superior for any trait.
Alabama would release such a cultivar if a wider gene base
was desirable. Louisiana would release one if the seed were
not available from the public or private sector, while
Mississippi would release the cultivar if the origin of the
variety adds to a wider genetic variation and decreases

90

"genetic vulnerability" of the crop as a whole. In
Mississippi, this would be an exception rather than the rule.

All of the experiment stations use a foundation seed organi-
zation for release of cultivars. In only two instances, how-
ever, is this foundation seed organization controlled by the
experiment station. Only one state would not grant exclusive
release to a private concern, while two states would not grant
non-exclusive release to a private concern. The person who
arranges for exclusive release varies by state, however. In
Alabama, the breeder arranges for release after the variety
release committee approves. In Arkansas, the researcher re-
leases the cultivar through the director with advice of legal
aides. The Florida Foundation Seed Producers, Inc. arranges
release with the IFAS Cultivar Release Committee. In Kentucky,
the seed committee of the Agronomy Department releases the
cultivar with approval by the dean of agriculture. In
Louisiana, Mississippi, Oklahoma, and Tennessee, release is
accomplished through the experiment station. In North
Carolina, the NC Agricultural Research Service develops a con-
tract or Memorandum of Agreement with a private concern. In
South Carolina, the South Carolina Foundation Seed Association
arranges release. Virginia advertises for bids. Accepted
bid must be approved by the department head and experiment
station director.

The criteria used to select the private concern receiving an
exclusive release also varies by state. In Arkansas, it may
be done by a bid process or as a sole source release, while
in Kentucky, the ability to produce and market the seed are
primary criteria. Louisiana usually selects on a bid basis.

In Mississippi, the criteria require a private concern to have
the ability, dependability, and recognized integrity to pro-
duce and supply adequate amounts of high quality seed to users
at reasonable cost. Policy of the Mississippi Agricultural
and Forestry Experiment Station is to get seed of improved
varieties to farmers at the lowest possible cost to farmers.
South Carolina relies on the SC Foundation Seed Association
to make the selection. In North Carolina, a private concern
must have the capacity to increase seed and to make a commit-
ment to provide reasonable quantities of seed to farmers at
a reasonable cost. In Oklahoma, selection is based on a
company's track record for sales, and whether the agricultural
experiment station thinks they will push the variety. In
Tennessee, company interest in the variety along with marketing
capability in the area are the main criteria. Virginia selects
the company with the most experience in producing seed of the
crop and with the best mechanism for merchandising seed in
the area of adaptation.

Only two states usually make exclusive releases of cultivars.
Seven states seldom make exclusive releases, and three states
never make exclusive releases. Among the states that do make

91

exclusive releases, various factors underlie that decision.

In Alabama, market and product development are behind this
decision, while in Arkansas, the economic potential of variety,
its potential appeal to seed producers, and value of the culti-
var to the agricultural interests of the state are prime deter-
minants. Kentucky uses exclusive releases to provide a continu-
ing supply of seed to the farmer, while Louisiana grants
exclusive release to insure that seed or variety will receive
proper promotion and get in the hands of producers in instances
where public release probably would result in no interest by
a large number of private breeders. Mississippi believes that
development, marketing and use by producers could only be
successful through exclusive release. If volume of potential
demand is insufficient to attract participation by industry
through a general release, exclusive release is usually the
only viable alternative. This principally applies to new
varieties produced from seed and not through vegetative stock.
North Carolina uses the exclusive release procedure only when
it appears to be the only or best means of providing growers
the materials developed by the NC Agricultural Research Service.
South Carolina considers exclusive release when the possi-
bility exists of the cultivar not being promoted or marketed
through normal channels. In Tennessee, exclusive release
occurs for species for which state foundation seed organizations
cannot produce seed. Virginia uses exclusive release when
this is the only method of assuring adequate seed production
and merchandising; usually for crops where seed must be pro-
duced outside the state. Texas uses exclusive release to
maximize public benefit and to assure that the cultivar gets
used .

Only two states do not receive royalties or payment when they
make an exclusive release to a private concern and only three
states report that they receive no royalties or payments for
a non-exclusive release. On the other hand, only one state
receives royalties or payments when the cultivar is released
through a foundation seed organization.

In summary, the agricultural experiment stations in the
southern region require that experimental forage cultivars
be tested at multiple locations within the state and in
multiple years before they are released. Testing includes
reaction to grazing, animal performance, nutrient analysis,
proximate analysis, and in most cases, performance as hay/silage,
simulated grazing and in vitro analysis. Factors considered
in release of forage cultivars at all stations are yield,
persistence, resistance, area of adaptions and undesirable
traits. Other factors considered by at least 75% of the states
are origin, breeding procedure, cultivar description, statement
on intended use, uniqueness, and plan for seed/stock increase.

92

COMPOSITION AND RUMINAL AVAILABILITY OF SULFUR IN COOL-SEASON
GRASSES

B. P. Glenn and D. G. Ely

U. S. Department of Agriculture and University of Kentucky

The availability of sulfur (S) from forages consumed by the
ruminant is dependent on forage S, ruminal S and the
interactions with nitrogen (N) compounds in the forage and
rumen. Supplementation to tall fescue with elemental S
increased total S digestibility, retention and abomasal
protein S recovery by wethers (Glenn and Ely, 1981a and
1981b) . Supplementation with nitrate N tended to reduce N and
S retentions and increase abomasal nonprotein S recovery.

These data suggest the total S to total N ratio in forages may
not be as important in defining ruminal degradability as are
relative amounts of different forms of forage S and N. The
objective of the studies summarized herein was to measure
effects of forage composition on ruminal availability of
forage S.

Tall fescue (Festuca arundinacea Schreb.) and orchardgrass
(Dactylis glomerata L.) were fertilized with 3 rates of N (0,
100 and 300 kg/ha) and 2 rates of S (0 and 150 kg/ha) in a
randomized complete block design with 4 replications per
treatment. Forage N and S composition and ruminal N and S
disappearance from forages were measured in samples obtained
at 5 dates from April 17 to June 27 (Glenn £t al. , 1980) .
Nitrogen fertilization increased total N, nonprotein N and
protein N content (mg/g forage) of both grasses. In spite of
similar total N concentrations, nonprotein N content was
higher for tall fescue than orchardgrass. Protein N was
higher for orchardgrass than tall fescue. Nitrogen
fertilization reduced total S and nonprotein S concentrations
(mg/g forage) and increased protein S content of both grasses.
Sulfur fertilization increased all forage S components.
Nonprotein S concentrations tended to be higher in tall fescue
but protein S was higher in orchardgrass compared with tall
fescue. Total N content was negatively correlated with
nonprotein S content (tall fescue r = -.53; orchardgrass, r =
-.31; P<.001). Nonprotein S content was negatively correlated
with nonprotein N content (tall fescue, r = -.27;

93

Table 1. — Disappearance of Forage Sulfur (%)

Item

Fertilizer treatment

ON-OS

0N-150S

300N-OS

300N-150S

SE

Sulfur

Tall fescue

Soluble

68.7

76.0

37.4

56.8

1.3

Insoluble

14.4

10.9

37.0

25.0

1.8

Total, 24

hr

83.1

86.8

74.4

81.8

Orchardgrass

Soluble

64.9

71.3

26.0

43.0

1.3

Insoluble

20.0

17.3

42.5

32.1

1.8

Total, 24

hr

84.9

88.6

68.5

75.1

orchardgrass, r = -.53; P<.01). Total nonprotein amino acid
concentration was greater in fescue while total hydrolyzable
amino acid content was greater in orchardgrass. Orchardgrass
may utilize available S and N for plant protein synthesis more
effectively than tall fescue due to either different nutrient
requirements or more efficient nutrient metabolism.

Ruminal N and S disappearance from the fertilized tall fescue
and orchardgrass was measured by the nylon bag technique in
rumen-f istulated steers. Water-soluble nutrient disappearance
was measured as the initial 0-hr nutrient loss from forages in
bags immersed in water and was correlated with loss at 6 hr
(N, r = .88.; S, r = .99). Subsequent insoluble disappearance
occurred in situ for 24 hr and was calculated as the
difference between disappearances at 24 and 0 hr. Soluble dry
matter, N and S disappearances (%) averaged 34.9, 45.3 and
59.7 for tall fescue and 27.4, 30.9 and 51.3 for orchardgrass,
respectively. Extent of forage N disappearance at 24 hr was
highest from grass fertilized with 300 kg N/ha and no S (81.1%
from tall fescue and 76.4% from orchardgrass). Large
differences in forage S disappearance were noted due to
fertilization (see table 1). Sulfur fertilization increased
extent of forage S disappearance. Extent of forage S
disappearance at 24 hr was lowest from grass fertilized with
300 kg N/ha and no S.

Soluble S disappearance from forages was negatively
correlated with total N and nonprotein N concentrations in
forage and positively correlated with total S and nonprotein
S concentrations. Greater losses of the rapidly soluble N
and S from tall fescue than orchardgrass were a result of
higher concentrations of nonprotein components in tall
fescue.

Altering ruminal solubilization of S from forage may affect
microbial uptake of the solubilized or available forage N and
S. Established tall fescue and orchardgrass plants were

94

transferred from soil and maintained hy droponically in four
nutrient solutions containing 2 rates of N (0 and 268 ppm)
and 2 rates of S (0 and 134 ppm)(Glenn et al., 1981c).

Changes in forage N and S components were similar to those
seen in the field study. Solutions were treated with S-35
and labeled grass was harvested. Percent of the total
absorbed S-35 which was absorbed into shoots were 29.4, 78.4,
29.1 and 69.7 for tall fescue and 9.0, 60.5, 53.4 and 55.0
for orchardgrass treated with ON-OS, 0N-134S, 268N-0S and
268N-134S, respectively. Grasses were incubated in ruminal
fluid in a closed, batch system. In vitro l^S production and
percentage of grass radioactivity recovered as and

microbial protein were higher for grass treated with ON-OS
and 0N-134S compared with high N treatments. Grass S
incorporation into microbial protein was calculated according
to a modification of the equation by Walker and Nader (1968).
Rate of grass S incorporation (yg/g grass /hr) after 60 min of
incubation was 79, 117, 14 and 83 for tall fescue and 59,

100, 16 and 133 for orchardgrass. Rate of microbial protein
synthesis (yg CP/g grass/hr)(60 min) was 5447, 8059, 926,

5713 for tall fescue and 4040, 6878, 1090 and 9157 for
orchardgrass. Sulfur fertilization of cool-season grasses
may have increased total S and nonprotein S solubility and
uptake into microbial protein in the rumen. Furthermore,
levels of N fertilization used for grasses may reduce
solubility and extent of forage S disappearance and limit
microbial use of S for protein synthesis.

Further research is needed to define forage protein and
carbohydrate fractions that will predict efficiency of use of
forage S and N in the gut to improve ruminant production from
high dietary forage inputs.

REFERENCES

Glenn, B. P., and Ely, D. G.

1981a. Effect of tall fescue supplementation with

sulfur, nitrate and starch on abomasal and plasma
amino acids in the ovine. Nutr. Rep. Inti.
24:323.

1981b. Sulfur, nitrate and starch supplementation of
tall fescue for the ovine. J. Anim. Sci.

53:1135.

Glenn, B. P.; Ely, D. G.; and Glenn, S.

1980. Ruminal availability of tall fescue sulfur. J.
Anim. Sci. 51 (Suppl. 1):238. (Abstract)

Glenn, B. P.; Ely, D. G. ; Glenn, S.; and Bush, L. P.

1981. Availability of tall fescue sulfur for ini vitro
incorporation into microbial protein. J. Anim.
Sci. 53 (Suppl. 1):38. (Abstract)

Walker, D. J., and Nader, C. J.

1968. Method for measuring microbial growth in rumen
content. Appl. Microbiol. 16:1124.

95

KOCHIA — FORAGE OR WEED?

L. M. Rommann

Oklahoma State University

Kochia scoparia is a warm season annual forb best adapted to
the drier areas of the Great Plains states from North Dakota
through Texas. It is considered as serious weed pest in both
rowcrop and small grain cropland but it has also been used for
grazing (after small grain harvest) or an emergency hay crop
in years of grain failure. These uses have been common for
over 50 years.

A 1947 report from South Dakota State University showed first
cutting kochia to be adequate for wintering beef heifer
calves. They gained .95 lbs per day on kochia compared to 1.8
lbs per day on alfalfa hay. Feeding second cutting kochia
caused the heifers to lose weight.

Texas Tech (Lubbock) research found kochia production going
from 1.5 tons per acre on May 29 to 5.0 T./A on July 14 with a
corresponding drop in crude protein from 25% to 13%. Yields
of irrigated kochia at the Clovis, New Mexico Plains Branch
Station of 12.5 tons per acre have been produced by H.D{
Fuehring, NMSU. Water and N were not limiting factors. Pro-
tein levels ranged from 9.3% in June to 6.9% in August. These
yield data indicate that 30 to 60 lbs of N are required for
one ton of dry matter production.

Oxalate content in kochia appears to be about 7.0%. Oxalate
can crystallize in the liver and kidneys of animals restricted
to a diet of kochia for 60-90 days. Death has been reported
within 60 days. Changing the diet appears to alleviate the
problem.

Alleleopathy to subsequent crops is apparently significant.

At Clovis, sorghum following kochia yielded only 1600 lbs per
acre when irrigated six times. According to Fuehring, the
sorghum plants showed water deficiency stress within a short
time after irrigation. Wheat yields were also reduced. The

96

al leleopathic compound(s) are leachable from the soil within
one year.

In western Oklahoma, kochia has long been recognized as weed
in cropped areas but it has also been used for grazing in dry
areas after wheat harvest. It has been tried as a planted
forage crop in eastern Oklahoma (40"-50" rainfall area). Mod-
erate success was achieved by one producer in 1980, a very dry
summer. In 1981, this producer and several others had no suc-
cess.

As kochia becomes more mature it may become unacceptable to
grazing animals. R.L. Dalymple, Noble Foundation, Ardmore,

Ok. used kochia as one forage species in an alternating graz-
ing program in 1982. Gains were good during the first two
grazing cycles but in August the animals refused to eat
kochia. This resulted in a weight loss of more than three
pounds per animal per day.

We at OSU do not recommend kochia as a planted forage crop.

If it is available, it can be used for grazing or hay. Other
forages can be more dependable under the same fertility pro-
gram with fewer potential animal health problems.

REFERENCES

Baker, L. 0.

1974. Growth and water use efficiency of seven annual

plant species. Proc. W. Soc. Weed Sci . (Abstract)
27:73-74.

Coxworth, E. C. M.; Bell, 0. B.; and Ashford, R.

1968. Preliminary evaluation of Russian thistle, kochia,
and garden atriplex as potential high protein con-
tent seed crops for semiarid areas. Canad. J.
Plant Sci. 49:427-434.

Erickson, E. L.

1947. Forage from kochia. I. Some plant characteris-
tics and forage production. S. Dak. Agr. Exp.

Sta. Bull. 384.

Sherrod, L. B.

1971. Nutrituve value of kochia schoparia. I. Yield

and chemical composition at three stages of matur-
ity. Agron. J. 63:343-344.

97

NO-TILL FORAGE ESTABLISHMENT

Harlan E. White

Virginia Polytechnic Institute and State University

Alfalfa acreage is increasing in Virginia. One of the primary
concerns in establishing new stands of alfalfa and other
forages is the threat of soil erosion while the new seeding is
becoming established in a well -til led seedbed. Resulting ruts
and gullies damage equipment and are dangerous to equipment
operators. In addition to conserving soil, no-till seedings
conserve moisture already present in the seedbed. This, plus
the dramatic reduction in water run-off, improves the water
supply for the new seedlings. Less time and fuel are required
to seed using no-till methods and rocks remain below the soil
surface. Technology is now available to successfully establish
forages without the need fop tillage and preparation, of a fine
seedbed.

The new no-till procedures are becoming widely accepted by
Virginia producers. A survey conducted in the fall of 1982
indicated that 82 sod seeders were available in that state,

80% of which were purchased during 1982. Aoproximately 2200
acres of alfalfa and 2300 acres of tall grass - clover were
were seeded during 1982, which was the first season following
the introduction of the no-till procedures.

NO-TILL REQUIREMENTS

Basic to successfully establishing new stands of forages by
no-till methods is an understanding of the requirements for
the procedure. Several "musts" are:

1. Living competition must be eliminated.

2. Heavy thatch and plant growth tall enough to shade the
soil surface must be removed.

3. The seedling must be orotected against a wide spectrum of
i nsects .

4. Seed must be Dlaced in the soil but no deeper than one
i nch .

5. Soil fertility must be medium to high with a dH of 6. 4-6. 7.

98

BASIC PROCEDURE

Removal of existing plant growth is accomplished by grazing
and/or mowing. Elimination of competition from growing plants
is dependent primarily upon herbicides. The following general
"recipe" is a guideline to follow:

Apply 2,4-D if broadleaf weeds are present. After at least 10-
14 days, apply Paraquat plus surfactant. Wait 14-20 days and
make another application of Paraquat. Seed 15 lb of inoculated
alfalfa seed per acre plus 10 lb of 10 G or 7 lb of 15 G
granular Furadan per acre in the row with the seed.

INSECTICIDE

Furadan is a necessary part of the management package in order
to protect the alfalfa seedling from insects. The specific
insects or complex of them involved are not known and will
vary with location and time of year. The granular form
of Furadan must be placed into the soil in the row with the
seed in order to meet label requi rements . It is desirable to
place the seed and Furadan in separate boxes on the seeder.
However, Furadan can be mixed with the seed in the seedbox and
separation will not occur as the seeder travels across the
field. If the seeder being used has an agitator in the seed-
box, separation of the Furadan is likely to occur. To prevent
this separation, disengage the agitator.

FITTING INTO THE FORAGE SYSTEM

There are many different situations in forage systems where
no-till alfalfa or other forage species can fit. In most
cases, seeding as part of a normal crop rotation will aid in
assuring adequate soil fertility and pH. There is concern that
some producers may attempt to seed alfalfa in areas with
shallow soils whose fertility and pH are too low to produce
high yielding alfalfa. If soil fertility and/or pH is low,
fertilizer and/or lime should be applied at least six months
prior to seeding. Alfalfa should not be seeded into an old
alfalfa stand. The field should not have had alfalfa growing
in it for at least two years prior to seeding.

SEEDING IN SOD

No-till seeding into a perennial pasture or hay sod can be done
effectively in either spring or fall using some variation of
the "recipe". Of particular concern when seeding into a sod,
especially in spring, is the lack of residual weed control.
Herbicides used to suppress the sod do not control weeds that

99

germinate later and compete with the new alfalfa seedlings.
Another concern is that occasionally Paraquat may not effec-
tively suppress orchardgrass sods in spring. Unless the sod
is primarily tall fescue, it is usually best to make the no-
till seeding in August rather than in spring. Two applications
of Paraquat on tall fescue after growth begins in spring are
effective in suppressing the sod, permitting alfalfa to become
established.

Fall seeding offers the advantage of less weed competition but
insect pressure and soil moisture stress are usually greater
than for spring seedings. An alternative to seeding into sod
in spring is to graze or harvest hay until late July, then
spray with two applications of Paraquat and sod-seed by mid-
August. Other alternatives are to graze the sod in spring or
take a spring hay cutting. Then spray the mowed or grazed sod
with 1 qt. of Paraquat per acre and sod-seed a summer annual
such as sorghum-sudangrass , millet, or perhaps grain sorghum-
soybeans. After the summer annual is harvested for forage in
early August, allow 4-8 inches of regrowth, apply 1-2 pt. of
Paraquat per acre, and then seed no-till. Any regrowth by the
summer annual grass or growth from weeds after the forage crop
is seeded should be mowed if it reaches a height of 6-8 inches.

SEEDING INTO SMALL GRAIN

There are several ways to successfully seed alfalfa or other
forages no-till into a small grain crop in the spring. One
method is to spray the small grain with 1-2 pts. of Paraquat
per acre when growth is 4-6 inches tall, then seed the alfalfa.
The small grain will make regrowth which must be mowed when
5-6 inches tall to prevent smothering the alfalfa seedlings.

Forages may also be seeded without tillage into standing (8-
10 inches tall) small grain prior to harvesting for silage.

Rye harvested for silage in the boot stage will normally
produce regrowth which must be mowed when 4-6 inches tall to
reduce comoetition to the alfalfa seedlings. Barley and
wheat cut at the dough stage will produce very little regrowth.

Forages may also be seeded into small grain stubble after a
silage or grain harvest. If the silage harvest was made prior
to dough stage, wait 5-10 days for regrowth to develop, then
apply 1 pt. of Paraquat per acre to burn back the regrowth
and kill weed seedlings. If the harvest was made at dough
stage or later, apply 1 pt. of Paraquat per acre immediately
and seed the alfalfa. Since grain harvest is quite late in
the spring, waiting until early August to spray with 1-2 pints
of Paraquat per acre and then seeding may be best. Volunteer
small grain must be mowed after the seeding if it reaches a
height of 5-7 inches. Another option is to apply Paraquat
and seed a summer annual grass by the no-till method after
the small grain crop is removed. The forage is then seeded

100

in August following the summer annual as discussed earlier.
SEEDING AFTER CORN

No-till planting of forages may also be successful in fields
planted to corn the previous season. Preferably, the field
would be planted to a small grain cover crop in the fall, but
this is not absolutely necessary. Caution should be taken that
residues from herbicides applied for the corn are not present
in the spring. When the intention is to seed no-till in the
spring following corn, short residual herbicides such as
Bladex and Dual or Lasso should be used on the corn. The
seeding can be done in mid-March but Paraquat may not be
needed at that early date if the seedbed is free of weeds.

Be sure the seedbed is free of even very small weeds before
deciding not to apply Paraquat.

101

TECHNIQUES USING ELECTRONIC COMMUNICATIONS

Clement E. Ward
Oklahoma State University

Those of us in extension have an opportunity to utilize modern
communications and computer technology in our extension pro-
grams. Many of us are experiencing a period of tight budgets
and often travel and printing funds are among the first areas
targeted for reduction when belt tightening occurs. Yet, ex-
tension faces increasing accountability pressure to be more
effective. Electronic extension delivery is one means of reach-
ing more people at less cost than some of the more traditional
means, namely printed extension reports and county level meet-
ings. This does not mean printed materials and county meetings
will be replaced entirely, only reduced or conducted differently.

My experience with electronic communications and computer tech-
nology comes largely from work with electronic marketing of
agricultural commodities. Let me mention electronic marketing
briefly. Electronic marketing involves using modern communica-
tions and data processing technology to market agricultural
commodities , The objective is to create a centralized trading
arena where all potential buyers and sellers can compete and
finalize trades. Buyers and sellers use telephones or computer
terminals to communicate with others in the market. Commodities
are sold based on description, often by an unbiased or impartial
third person. Thus, commodities frequently remain on the farm
until the sale is completed and an acceptable price established.

The concept of electronic marketing is not new. Electronic
marketing was first commercialized in 1961 when the Ontario
Pork Producers Marketing Board began marketing slaughter hogs
by teletype auction. The first commercial electronic market in
the U.S. was a telephone auction for feeder pigs, begun by MFA
Livestock Marketing Cooperative in Marshall, Missouri in 1965.

The first application of computer marketing was in 1975. Plains
Cotton Cooperative Association of Lubbock, Texas began marketing
cotton over a computer network called TELCOT. Another applica-
tion of electronic marketing uses video communications techno-
logy. The first commercial video auction began in Montana for

102

feeder cattle in 1976.

Now, how can we use the same electronic communications and com-
puter technology in our extension programing that is used in
marketing? I will discuss three broad types of electronic
technology similar to three broad categories of electronic mar-
keting. First, telephones; second, video tape and television;
and third, computers.

USING TELEPHONES IN EXTENSION DELIVERY

All of us use the telephone in our extension programs for one-
to-one contact with clientele. However, two offshoots can be
especially useful. First is the conference telephone for tele-
lecture or teleconference meetings and the second is the code-
a-phone .

A conference telephone connection enables several people at one
end of the connection to talk with several people at the other
end of the connection. Individuals may each have a phone and
be in separate locations or a group of people may use speakers
and microphones with just one phone at each end of the
connection .

An example of a telelecture as I use the term is when I am in
my office and presenting extension information with an off-cam-
pus group at one location. An example of a teleconference as
I use the term, is when I am in my office meeting with two or
more off-campus groups at two or more locations. OSU agricul-
tural economists regularly use teleconferences in presenting
livestock and grain outlook and policy information. Telelec-
tures or teleconferences usually need to be supplemented with
overhead transparencies, slides, video tapes, or on-site demon-
strations to be most effective. They are cost effective for
small groups in distant locations from the campus or when you
want to present the same material to several groups in several
locations .

A code-a-phone is similar to a telephone answering service
which all of us are familar with. At OSU we also use code-a-
phones for livestock and grain outlook information. An audio
tape recording is made and when clientele dial a specific phone
number (it can be a regular long distance number or an 800 or a
900 long distance number) the audio tape is played automatic-
ally. This is particularly useful for keeping clientele in-
formed on things that require periodic updates. An example for
agronomists might be to use it in conjunction with plant path-
ologists and entomologists regarding insect and disease alerts
and prevention or management solutions. It may be useful in
terms of seed or fertilization rates, varieties and other fac-
tors given changing weather and economic conditions.

103

USING VIDEO TAPE AND TELEVISION IN EXTENSION DELIVERY

All of us probably have developed slide-tape sets in our exten-
sion work. While useful, slide-tape sets have limitations.

Video tapes often overcome some of those limitations. Video
tapes can be made with or without a great deal of planning and
preparation. For example, you may have a specific crop field
day in your state. Since several people cannot attend, selec-
ted segments of the program could be video taped while they are
being presented and the tapes made available to groups of per-
sons who did not attend. Even among those who are present,
some participants comment that they would like to see or hear
a given presentation again. Video tapes enable them to do that.

Planned video tapes may be made without the live audience and
then the tapes can be used in an educational role. These tapes
may require more preparation. Video tapes are especially use-
ful because of the voice and visual editing capabilities. Video
can be an important adjunct to a telelecture or a teleconference
meeting as well as in-person meetings or conferences. Video
tapes may also be edited for TV, either farm or news programs
or educational television.

Two economists at OSU used talk-back television to conduct an
in-service training session for county extension directors.
Talk-back television enables viewers at several locations to
watch on television those conducting the program. In our ex-
perience, the studio where the in-service program originated
had two cameras. One was in front of us enabling us to use
the blackboard or flipcharts. A second was overhead, and
pointed toward the desktop to focus on papers, worksheets, dem-
onstrations, or other materials on the desk or table. Slides,
video tapes, or demonstrations, also can be used with this
type of presentation. Dedicated phone lines enable participants
to talk to the person or persons conducting the program or to
people at other receiving locations. Our experience was mixed.
We came away believing in the usefulness of talkback television,
but we found that a practice session is desirable in order to
effectively make use of visual aids.

Some states make effective use of educational television. Aud-
ience numbers are smaller compared to commercial television but
time is more available. Therefore, specialists have an oppor-
tunity to delve fairly deeply into a given subject area which
they cannot normally do in 1^-3 minutes time for personal inter-
views or video tapes on commercial television.

Video tape equipment, talk-back television and educational tel-
evision have a high fixed cost. However, if costs are measured
in terms of persons reached, their cost effectiveness can be
argued convincingly.

104

USING COMPUTERS IN EXTENSION DELIVERY

This is truly the age of computers and we need to make the best
possible use of this available technology. Already, many states
have micro-computers in all their county extension offices.

While part of the reason for this is for office management,
there are a number of other potential uses for us as state
specialists. One use is electronic mail. We can instantly
send written information to area and county extension staff and
thereby keep them up to date. We can send tabular and graphic
material as well as word charts from which they can make over-
head transparencies for telelectures and teleconference meetings.
By combining electronic mail and word processing, we can tailor
extension information to whatever part of the state or specific
commodity is appropriate. For example, variety tests may be
tailored to specific parts of the state based on the annual
precipitation levels and soil types.

In a similar manner, state specialists can receive reports from
farmers and extension staff by electronic mail. For example,
area or county extension staff might report such things as
planting or harvesting progress, and rainfall and pasture cond-
itions. We then can use such information in timely educational
programs. Such timeliness may enable us to identify the teach-
able moment and capitalize on it.

Perhaps because of my economic bias, one of the greatest advan-
tages of micro-computers is their usefulness in making more
accurate, timely, complex, and complete management decisions.
Complex interdisciplinary decision models can be developed and
made readily available to teach producers fundamental agronomic
and economic principles. You can probably think of better ap-
plications than I can, but three examples of decision aids
might include: (1) studying the interrelationship between
weather, soil type, and other factors to determine the desir-
ability of low-till versus conventional planting; (2) studying
the relationships between planting time, weather, soil type,
and of selected plant varieties to fertilizers, to determine
optimum fertilization amounts and timing; and (3) studying the
trade-off between possible insect and disease damage and yield
loss versus cost of control measures, to determine the type and
amount of insect control for various crops.

CONCLUSIONS

Modern communication and computer technology is changing the
role of extension. No longer can we continue doing what has
worked well for us in the past. Our clientele is becoming more
sophisticated and demanding more from extension, despite not
providing us with many resources as in the past. The challenge
is clear, we must adapt our extension programs and delivery
systems to the technology or lose clientele support.

105

COMPUTERIZED HAY MARKETING

Gerrit W. Cuperus
Oklahoma State University

Alfalfa is the only major crop in the United States with no
organized marketing system. In Oklahoma, alfalfa is commonly
grown for stables and dairies throughout Oklahoma and surround-
ing states. A large proportion of Oklahoma alfalfa is raised
and sold to other producers. This transaction has histori-
cally been a risky and often non-profitable undertaking for
both buyers and sellers. Growers have often had insufficient
information about potential buyers, their hay needs, and how
much they are willing to pay. Buyers lack information about
where and how much hay is for sale, its quality and how much
growers want for it. Thus, a more efficient marketing system
would result in (1) better information for both buyers and
seller on hay demands and supplies, and (2) better market in-
formation on hay prices based on quality factors. Haymarket, a
computerized alfalfa marketing system, is designed to bring
buyers and sellers together.

The Oklahoma Alfalfa Hay and Seed Association (OAH&SA) is the
sponsoring organization for Haymarket. Haymarket is designed
to serve two purposes: (1) Locator Service and (2) First
Evaluation. From the Haymarket information, buyers will know
the location of alfalfa and its relative quality. An un-
biased third party grader will visually grade the alfalfa for
maturity (3 catagories), foreign material (type and amount),
and color (4 catagories). Random core samples are also taken
for percent crude protein and moisture. The visual evaluation
attempts to answer some of the questions a buyer would ask over
the phone. All graders must be approved by the OAH&SA Board
of Directors and complete training once/year.

Information currently mailed to over 500 potential buyers
includes: grower name, address, and phone numbers, harvest
package, cutting, tons, percent protein and moisture, sample
date, foreign matter (type and amount), maturity, color, and

106

comments. Information will also be available in a dial-up
basis by potential buyers using a computer terminal. Cost for
growers is $ 1 0/ 1 ot (1 cutting off 1 field) plus $6 for chemical
analysis.

Receptivity from both buyers and sellers has been extremely
favorable. Both buyers and sellers see opportunity to reduce
their costs and increase profitable marketing. Potential
benefits to producers could be as high as $10/ton.

107

EFFECT OF FERTILIZER APPLICATION AND GRAZING MANAGEMENT ON
GRAZED NEW ZEALAND HILL COUNTRY

M. Greg Lambert and David A. Clark

Grasslands Division, DSIR, New Zealand

INTRODUCTION

Approximately 13 million ha, or 50%, of New Zealand's area is
pastoral, supporting populations of 2.9 million dairy cattle,

5 million beef cattle, and 70 million sheep. Some 70% of
export income is from sale of agricultural, horticultural, and
silvicultural products, and 85% of this is from wool, meat, and
dairy products.

About 4.5 million ha is classed as hill country (Brougham and
Grant 1976), including land with soils from volcanic to sedi-
mentary origin, annual rainfall from 350 to 2,500 mm, and
altitude from sea level to 1,000 m. Pastures in hill country
are "permanent," are grazed year-round, and emphasis is on
minimum use of conserved feed. Primary limitations to pasture
production are water supply in the warm season, and soil N
supply at all times other than during drought. Irrigation is
rarely practiced; the major N input to the pastoral N cycle is
N fixation by legumes, and fertilizer N is generally used only
to boost pasture growth to overcome seasonal feed deficiencies.

In hill country, farm income is generated mainly from sales of
wool (43%) , sheep (29%) , and beef cattle (24%) (NZMWBES 1983) .

Profitability per hectare is a major determinant in making
management decisions. Increases in per hectare productivity
and profitability are sought through attention to fertilizer
application regime, stocking rate, grazing management, genetic
merit of livestock, introduction of superior pasture cultivars/
species, and control of brush weeds.

The trial described here was initiated to investigate
influences of two of the above variables, fertilizer
application and grazing management, on low fertility, "moist"
hill country in the North Island of New Zealand.

108

EXPERIMENTAL PROCEDURES

The trial is in progress currently, although with modified
experimental treatments, at "Ballantrae, " a hill country
research area of Grasslands Division, DSIR, located near
Palmerston North at latitude 40°S, and 125-350 m altitude.
Average annual rainfall is about 1,280 mm, relatively evenly
distributed, and average (max. + min./2) 1.2 m air temperature
is 16.1°C in February and 7.2°C in July. Soils are derived
from Tertiary sediments.

Ninety-nine ha of dissected hill country was divided into 10
f armlets. Treatments were two fertilizer levels (LF = 11 kg P
ha-^ yr“l as superphosphate, HF = 57 kg P ha-^- yr“l plus lime)
and three grazing managements [rotationally grazed Angus
breeding cows (RGC) ; rotationally grazed breeding ewes (RGS) ;
set stocked ewes (SSS) ] , in factorial arrangement with
replication (3X) of SSS at both fertilizer levels. Legume
(white, red, and subterranean clovers, and big trefoil) seed
was oversown in order to ensure a responsive pasture legume
component. Only small amounts of fertilizer had been applied
in previous years, and soil available P status was very low.

RGC and RGS animals were allocated a new area of pasture three
times each week; rotation length was longest in winter (55-
70 days) and shortest in spring (21-25 days) . "Set stocking"
was continuous grazing at constant stocking rate throughout
the year, apart from natural increase which occurred in all
grazing managements. Young stock were removed from all
f armlets at weaning. Stocking rate was the same across
grazing managements within each fertilizer level, and was
higher for the HF than the LF level. Stocking rate was
increased in annual increments from 6.5 (in 1975) to 12.0 (in
1981) stock units [(SU) 1 SU = 1 ewe plus lamb(s) to weaning;

1 cow plus calf to weaning = 6 SU] ha“l on LF f armlets, and
from 8.8 to 16.1 SU ha-1 on HF f armlets. Increase in stocking
rate was designed to maintain similar grazing pressure as
pasture production increased in response to treatments.

Lambert et al. (1983) give more details of experimental design
and procedure.

Measurements of pasture and soil parameters, and of animal
performance, were made during the period considered here — 1975
to 1982.

109

RESULTS AND DISCUSSION

Pastures

Pasture production, measured by a "trim technique" using
grazing exclosures, was more strongly influenced by fertilizer
application than grazing management treatments (Table 1) .
Response in the first year was only 9% in favor of HF, but
subsequently was 21-50%. This lag occurred while legumes
responded to fertilizer application, and soil N availability
was increased as a result of cycling of symbiotically fixed N
through animal excreta and pasture decay cycles. Small-plot
trials (Lambert and Grant 1980) indicated that fertilizer
level differences were due predominantly to the superphosphate
rather than the lime component of the HF regime.

Pasture production was similar on sheep-grazed treatments, but
over the 6-year period an average depression of about 9%
occurred on RGC f armlets. This was probably a consequence of
treading damage while soils were very wet in winter and early
spring. Herbage mass measurements, coupled with estimates of
animal intake, indicated that RGS pastures actually had 20%
higher growth rates in spring and early summer , or about 12%
on an annual basis, than did SSS pastures. It appeared that
the trim technique we used overestimated production in grazed
SSS pastures more than in grazed RGS pastures (Field et al.
1981) . This was probably a result of reproductive tillers
being more frequently defoliated in SSS than in RGS pastures
(Clark et al. 1982). As a consequence, the reproductive surge
which occurs during spring and early summer was depressed more
in SSS than RGS pastures.

Botanical composition was influenced by treatments (Table 1) .
HF pastures had higher ryegrass and legume and lower low-
fertility- tolerant (LFT) grass content than LF pastures. RGC
pastures were more legume- and ryegrass-dominant and had lower
LFT grass content than sheep-grazed pastures. The lower
density of the RGC pastures probably favored legume growth,
and treading damage gave ryegrass a competitive advantage over
the more susceptible LFT grasses.

Pasture structure was influenced by grazing management.

Density was reduced by rotational grazing, especially with
cattle (Table 1) , and the fewer plant parts tended to be
proportionately larger in these pastures. Vertical
distribution of biomass differed for the relatively prostrate
SSS and erect rotationally grazed pastures, e.g., 55% of
above-ground biomass was below 10 mm in SSS pastures, but only
35% in rotationally grazed pastures. This difference could
make rotationally grazed pastures more susceptible to damage
from overgrazing.

110

Table 1. — Pasture characteristics. Averages for 1975-81

Fertilizer

Management

LF HF

RGC RGS SSS

Pasture production
(kg DM ha-1 yr~l)

8910

11640

9580 10600 10390

Botanical composition (%)
Legumes

13

17

19 13 13

Ryegrass ^

18

25

28 22 18

LFT grasses

49

19

36 47 50

Pasture structure

Density (units m“2 x 10^)
Grass tiller wgt. (mg)
White clover leaf size
(cm^ leaf"-'-)

15 23 28

5.6 4.1 3.4

1.1 0.6 0.6

Low-fertility-tolerant grasses: mainly bentgrass ( Agrostis
spp.), sweet vernal ( Anthoxanthum odoratwi) , crested dogstail
(Cynosurus oristatus) .

Nutrient Cycling

N fixation, measured by the acetylene reduction method, was
approximately 30 kg N ha-^ yr--'- in 1974/75 (Grant and Lambert
1979), before treatments were imposed. In 1976/77 N fixation
had increased to 70 and 120 in sheep-grazed LF and HF pastures,
respectively, and 110 and 250 in RGC-LF and RGC-HF pastures,
respectively. Available N status of soils (to 75 mm depth) ,
assessed by a modified stress labile N (Ayanaba et al. 1976)
method in 1980, was higher in HF (69 kg N ha--'-) than LF (55 kg
N ha“l) soils. Although of low statistical significance (P =
0.25), RGC soils had a larger pool of labile N (71 kg N ha"-'-)
than soils under sheep grazing (59 kg N ha"-'-) . These values
are in accord with measured differences in N fixation. In
years 2-5 of the trial, legume content decreased at both
fertilizer levels; this appeared to be associated with an
increase in soil N availability and resultant increased
competitiveness of associated grasses.

Earthworm populations, estimated in 1979 using a formalin-
extraction method, were 24% higher in HF than LF soils,
presumably a result of increased organic cycling.

Ill

Table 2. — Average animal production (kg/ha) during 1975-82.

Fertilizer

Management

LF

HF

RGC

RGS

SSS

Wool

53

69

— —

61

61

Lamb

liveweight

215

297

—

244

268

Calf

liveweight

220

279

250

—

Animal Production

HF sheep-grazed treatments yielded 31% more wool ha--^ and 38%
more weaned lamb liveweight ha~l than LF sheep-grazed
treatments (Table 2) . A similar difference between fertilizer
levels existed for calf production from RGC farmlets (27%) .
These increased production levels were almost entirely a
consequence of the higher stocking rates maintained on the HF
farmlets in order to ensure similar utilization of pasture
across fertilizer levels (Clark and Lambert 1982).

Wool production was not different for RGS and SSS treatments
(Table 2) . Lamb production tended to be greater from SSS
farmlets in early years of the trial, at lower stocking rates.
In 1981/82, at a much higher stocking rate than that employed
by commercial farmers, RGS farmlets had higher lamb
production.

Pasture/Animal Interface

In hill country farming, the farmer attempts to match feed
supply and animal requirement, without recourse to large
inputs of conserved feed. Figure 1 illustrates typical
pasture growth and animal requirement curves in our LF sheep-
grazed systems, if stocked at 10 SU ha-^. Mating was in early
April, lambing in September, and weaning in early January.
Comparison of the two curves indicates that animal
requirements exceeded pasture growth during mid-July to mid-
September, and growth exceeded requirements at other times.

Two large buffers operated to smooth these inequalities :

(i) Animal intake was restricted to below maintenance
during the period of low pasture growth, resulting
in weight loss. Weight gain occurred later in the
year when pasture growth rates were higher. Average
annual minimum and maximum liveweights for our
experimental animals were 46.1 and 53.3 kg for ewes,
and 406 and 473 kg for cows, i.e., an annual weight
loss of 17% and 14%, respectively, from maximum to
minimum.

112

CL

Winter Spring Summer Fall

Figure 1. — Pasture growth and animal requirements in low

fertilizer, sheep-grazed systems stocked at 10 SU ha“l.

(ii) Mean pasture availability varied throughout the

year, from about 2,500 kg DM ha“^ above ground level
during summer to about 1,100 kg DM ha--*- at the end
of winter, prior to onset of rapid spring growth.

Despite these buffers, critically low pasture availability
can occur in winter or during drought, and in order to prevent
excessive stock losses farmers use fertilizer N to boost cool-
season pasture growth, or supplement with conserved feed.
Rotational grazing through the winter makes it easier to carry
autumn-grown pasture forward to the late winter when feed
supplies are low.

Excessively high pasture availability can be a problem in wet
summers. High levels of dead and senescing plant material
limit the ability of animals to select a high-quality diet.

It is our belief that a flexible approach to grazing manage-
ment can be advantageous. During periods of low pasture
availability, growth can be enhanced by rotational grazing.

We also believe that when growth conditions are favorable, and
pasture availability reaches levels which do not restrict
animal intake, then set stocking can maintain quality of
pastures at a higher level than if rotational grazing was
implemented. This increase in quality may have to be balanced
against decreased pasture productivity. However, where major

nutrient-supply limitations to legume growth exist in grass-
legume pastures, alleviation of these limitations will
probably elicit far greater responses in animal production
than will sophistication of grazing management.

REFERENCES

Brougham, R.W., and Grant, D.A.

1976. Hill country farming in New Zealand. Hill Lands,
Proc. Itit. Symp., pp. 18-23.

Clark, D.A., and Lambert, M.G.

1982. Animal production from hill country: effect of
fertiliser and grazing management. Proc. N.Z.

Soc. Anim. Prod. 43: 173-175.

Clark, D.A.; Lambert, M.G.; and Chapman, D.F.

1982. Pasture management and hill country production.

Proc. N.Z. Grassl. Assoc. 43: 205-214.

Field, T.R.O.; Clark, D.A.; and Lambert, M.G.

1981. Modelling a hill-country sheep production system.
Proc. N.Z. Soc. Anim. Prod. 41: 90-94.

Grant, D.A., and Lambert, M.G.

1979. Nitrogen fixation in pasture. V. Unimproved

North Island hill country, "Ballantrae. " N.Z. J.
Exp. Agric. 7: 19-22.

Lambert, M.G.; Clark, D.A.; Grant, D.A.; Costall, D.A.; and
Fletcher, R.H.

1983. Influence of fertiliser and grazing management on
North Island moist hill country. 1. Herbage
accumulation. N.Z. J. Agric. Res. 26: in press.

Lambert, M.G., and Grant, D.A.

1980. Fertiliser and lime effects on some southern North
Island hill pastures. N.Z. J. Exp. Agric. 8:
223-229.

NZMWBES .

1983. Supplement to the Sheep and Beef Farm Survey 1980-
81. N.Z. Meat and Wool Boards’ Economic Service
Pub. No. 1873.

114

RECENT PROGRESS IN FORAGE PRODUCTION AND UTILIZATION IN
SCOTLAND

Thomas David Alexander Forbes
Oklahoma State University

INTRODUCTION

The production and utilization of forage, both indigenous and
sown, from hill land has been one of the most important areas
of research since the Hill Farming Research Organization was
established in 1954. Early studies examined the ecological
status of the indigenous hill vegetation, its origin and its
relationship with soil type, and with grazing and burning
managements. Since then work has been carried out on the es-
tablishment and maintenance of sown pastures, particularly the
role played by white clover, on the improvement of utilization
of hill and upland swards by grazing animals and on the ef-
fects of utilization by grazing animals on growth and produc-
tion of hill pasture, among a very large number of research
activities .

THE INDIGENOUS VEGETATION AND LIMITATIONS TO ITS PRODUCTION

Table 1 summarizes the general relationships between the soils
and the main vegetation types of the hill. The groupings are
divided on the basis of soil drainage and soil acidity, with
the emphasis on agricultural importance. On soils with a pH
above 5.3 (mull soils) the vegetation is a high grade
Agrosti s-Festuca grassland with a large number of forbs and
most importantly with white clover present. Grazing pressures
are high and nutrient turnovers and decomposition processes
are rapid. On soils between pH 4.5 and 5.0 species poor
Agrostis-Festuca grasslands are found; clover is absent, de-
composition is slower and humus tends to build up. On still
more acidic sites with pH of less than 4.5 (mor soils) shrub
or grass heath may occur depending on past burning or grazing
history. The dominant species are those that are little
grazed such as Nardus stricta and Mol ini a caerulea and humus
begins to build up as peat. On the most poorly drained sites
acid peat bogs occur.

115

Table 1. Summary of the main soil and vegetation types of
the Scottish hills.

Soi 1

pH

Vegetation type

Brown earth
freely drained

5.3 -

6.0

Agrosti s-Festuca grassland
high grade or spp. rich

Gleys

poorly drained

5.3 -

6.0

As above with wet-land spp
Carex, Juncus

Brown earth
freely drained

4.5 -

5.2

Festuca-Agrost i s grassland
low grade or spp . poor

Gleys

poorly drained

4.5 -

5.2

As above Nardus and
wet-land spp. Carex,

Juncus

Podsol s

Peaty podsol s
freely drained

4.0 -

4.5

Nardus or Deschampsia/
Festuca grass heath
or

Calluna shrub heath

Peaty gleys
poorly drained

4.0 -

4.5

Mol ini a grass heath

or

Cal 1 una/Mol i ni a heath

Deep blanket
peat

poorly drained

3.5 -

4.0

Trichophorum/Er iophorum/

Cal 1 una bog

At the highest elevations climatic factors impose overriding
limitations on herbage production, but elsewhere on the hill
the interactions between climate, altitude, soil and vegeta-
tion variously limit pasture production, and thus potential
production varies considerably from site to site. As altitude
increases, so temperatures decline and the length of the grow-
ing season is reduced. Delay to the start of growth in the
spring can be a considerable problem particularly since the
demands of the lambing and lactating ewe are at a peak.

Problems of soil wetness combined with soil acidity are of
considerable importance in determining herbage production.
Decomposition rate is largely controlled by soil acidity and

116

this may be the limiting factor to the cycling of nutrients in
the soi 1 -pi ant-animal system (Floate, 1970).

Limitations to hill land pasture production are due to five
groups of factors - climate, site, soil, vegetation and man-
agement (HFRO, 1979). Some, such as climate and site, are per-
manent; others can be corrected at a greater or lesser cost.
Most recent work has concentrated on reducing the limitations
due to soil, vegetation and management. Limitations to pas-
ture use are two-fold: where the quality of the herbage is
good, the quantity of pasture and its regrowth capabilities
are limiting; where quality is low, the extent and pattern of
pasture use is limited by the nutritional penalties to the
grazing animal. Only the acid grassland falls into the former
category; the use of all other communities is limited by the
quality of the herbage.

Much of the early work on the improvement of indigenous pas-
ture, which highlighted the shortness of the growing season of
hill pasture, together with a better understanding of the nu-
trional requirements of hill sheep led eventually to the form-
ulation of the two-pasture system (Eadie, 1970). The two-
pasture system requires that a small area of ground (1 ha/15
ewes) be reseeded and managed alongside unimproved hill
ground. The improved pasture is used to provide feed of im-
proved quality during the critical periods of lactation, pre-
mating and mating. A consequence of the provision of improved
pasture is that pasture utilization improves overall and gen-
erally allows for an increase in stock number. A certain
degree of supplementation with hay and/or concentrates is nec-
essary during late pregnancy.

As the two-pasture system continued to be developed, various
problem areas were highlighted as requiring further basic re-
search. They included the important role of clover in the im-
proved pasture and the need to maintain the clover population,
the improvement of utilization of indigenous pasture by both
cattle and sheep, and the effects of utilization by sheep and
cattle on the growth and production of improved hill pasture.

THE ROLE OF CLOVER IN IMPROVED HILL PASTURES

The availability of nitrogen is a key factor in the productiv-
ity of hill pastures. Nitrogen, unlike lime and phosphate, is
rapidly lost from the soil and thus requires repeated applica-
tion. Hill pastures are frequently difficult to reach and ap-
plication of fertilizer is becoming increasingly expensive.
Newbould and Haystead (1978) have discussed the role of white
clover in hill pasture and the biological reasons for its im-
portance. Early work indicated that the appropriate strains
of Rhizobium are not always present in all hill soils or in
sufficient numbers to form an effective symbiosis (Holding
and King, 1963; Singer, Holding and King, 1964). More recent

117

studies (HFRO Biennial Report, 1982) have examined the rela-
tionships between mycorrhiza and white clover, particularly
since phosphorus uptake is thought to be increased with effec-
tive mycorrhiza/ white clover symbiosis and since once soil
acidity has been corrected phosphorus is the nutrient most
likely to restrict clover growth. The results so far have in-
dicated that as with Rhizobium/c lover interactions some
strains may be more beneficial than others. Other basic re-
search is being carried out on the rate of nitrogen fixation
and the influence of defoliation on the rate of fixation and
on the overall nitrogen economy of the clover plant. Results
indicate that the rate of fixation is influenced by the degree
of Rhizobium/ white clover association and by the supply of
photosynthate to the roots. Post-defoliation leaves and grow-
ing shoots are priority sinks for nitrogen with most of this
nitrogen coming from already assimilated nitrogen, mainly from
stolon material. Evidence for the transfer of nitrogen from
white clover to grass is somewhat inconclusive with l^N
enrichments of grass in pure and mixed swards differing only
slightly (HFRO Biennial Report, 1982).

THE IMPROVEMENT OF UTILIZATION OF INDIGENOUS HILL PLANT COM-
MUNITIES

Investigations into the improvement of utilization of indige-
nous hill plant communities began in 1977 and the first phase,
designed to study nutrient intake, ingestive behaviour and
diet selection ended in 1980. A second phase will examine the
effect of controlled grazing on the botanical composition of
these communities, their herbage production and nutritive val-
ue, and the nutrient intake of animals grazing them (HFRO
Biennial Report, 1982). Prior to this study the only avail-
able information related to Cal 1 una-dominant heather moor
(Grant et al . , 1978; Milne et aj_. , 1979) and Agrosti s-Festuca
grassland TFadie, 1967; Nicholson, 1967).

Measurements were made on six communities-

1. Agrosti s/Festuca grassland.

2. Nardus stricta - dominant dry grass heath.

3. Mol ini a caerulea - dominant wet grass heath.

4. Cal 1 una vul gar i s - dominant heather moor.

5. Cal luna/Eriophorum/Trichophorum blanket bog.

6. Perennial ryegrass (Lolium perenne) sown pasture.

The perennial ryegrass pasture was included to act as a link
with other studies on sown swards at H.F.R.O. and elsewhere.

Detailed observations on herbage intake, diet digestibility,
intake per bite, rate of biting and grazing time were made on
cattle and sheep grazing together on the grass and grass heath
communities (Forbes, 1982). Detailed studies were made at the
same time on associations between sward structure, botanical
composition, ingestive behaviour, diet selection and herbage

118

intake. On the indigenous swards the cattle and sheep selec-
ted diets of similar organic matter digestibility except in
the spring and autumn on short swards where the sheep obtained
diets 5 to 12 units of digestibility higher than those of the
cattle. Intake per bite was found to be the major determinant
of daily herbage intake in both species, and was influenced
primarily by sward height. Where intake per bite declined due
to declining sward height, rate of biting increased (Fig. 1).

Figure 1. The relationships between intake per bite,
rates of biting and sward height (Forbes 1982).

Increases in grazing time occurred where intake per bite was
particularly low, but the response was not consistent. The
cattle responded to increases in sward bulk density by in-
creasing rate of biting; the sheep increased grazing time.

The cattle responded to an increasing leaf: stem ratio by de-
creasing rate of biting; the sheep reduced grazing time. Very
low intakes per bite in the early spring on short swards,
where the digestibility of the diet selected was low, due to a
low green to dead ratio, led to digestible organic matter in-
takes by the cattle that were barely adequate for maintenance.

119

The cattle consistently ate higher proportions of green flower
heads and stems whilst the sheep consistently ate higher
proportions of forbs. To obtain these diets the cattle grazed
the surface horizons whilst the sheep grazed the base of the
sward. On short swards in spring the cattle were unable to
avoid eating a higher proportion of dead herbage than the
sheep.

The cattle and sheep altered their ingestive behaviour in a
consistent manner across the range of swards. Changes in diet
selection varied to a greater extent within season than within
swards. The selective ability of the sheep allowed them to
maintain the nutrient concentration of their diets. The cat-
tle modified their grazing behaviour to allow them to maximize
nutrient intake, particularly in the summer months. The dif-
ferent grazing strategies of the cattle and sheep allowed them
to be complementary rather than competitive grazers in the
summer months, and since the cattle grazed the surface hor-
izons this study confirmed the value of using cattle to manage
the vegetation in the summer months at no disadvantage to them
and some large advantage to the sheep.

EFFECTS OF UTILIZATION BY GRAZING HILL SHEEP AND BEEF CATTLE
ON THE GROWTH AND PRODUCTION OF HILL PASTURE

This work was undertaken because, though cutting and intermit-
tent grazing studies have shown that temperate pasture produc-
tion can be increased by controlled grazing (Brougham, 1959
and 1960; Jameson, 1963; Davidson, 1969), net herbage accumu-
lation (NHA) appears to be remarkably insensitive to varia-
tions in grazing management (Hodgson and Wade, 1978). In most
grazing trials, the estimates of herbage production, which in
reality are estimates of net change in herbage mass over time,
are inadequate for calculation or interpretation of the dynam-
ics of herbage growth and utilization. A series of experi-
ments by Bircham (1981), and Bircham and Hodgson (in press a
and b) and others (Grant et al . , 1981; Grant et al . , in press;
Arosteguy, 1982), were conducted that examined rates of her-
bage growth, and losses due to herbage consumption and senes-
cence and decomposition, in order to determine net herbage ac-
cumulation and the efficiency of herbage utilization.

The results of four field trials have shown consistently that
rates of herbage production per ha are greatest when swards
are maintained between 1000 and 1700 kg OM/ha with rapid de-
clines at lower levels but relatively small changes above
1000-1200 kg OM/ha. Figure 2 shows the results of a series of
experiments in which simple ryegrass/white clover swards where
maintained at different herbage masses throughout the grazing
season. The relative insensitivity of net herbage production
to wide range of continuous stocking treatments is a conse-
quence of rapid adaptive changes in sward characteristics. As
herbage mass is reduced individual tiller size is reduced but

120

tiller population density increases up to levels as high as
60,000 tillers/m^- (Fig. 3). Tiller population densities are
lower on cattle-grazed compared with sheep-grazed swards lead-
ing to lower herbage growth and net production on the cattle-
grazed swards later in the season.

J I i 1 1 I 1 l_

1 2 3 4 5 6 7 8

Sward Height (cm)

1 2 3 4 5

Leaf Area Index

Figure 2. The influence of variations in herbage mass on
rates of herbage growth, senescence and net production in
swards continuously grazed by sheep. The associations between
herbage mass, sward height and leaf area index for also shown.
(Bircham and Hodgson 1982)

The results indicate that there is little advantage to be
gained in terms of net herbage production, or in production of
weaned lamb by maintaining continuously stocked swards of a
herbage mass in excess of 1200-1500 kg/OM/ha (Fig. 4). Fur-
ther work is being carried out in order to define the optima
for cattle and mixed grazing systems.

121

I/)

o

o

o

Herbage Mass (kg/ha)

Figure 3. The influence of herbage mass on tiller population
density and growth per tiller in a sward continuously grazed
by sheep. (Bircham 1981)

Figure 4. The influence of herbage mass maintained under
continuous stocking management in (a) LWG of individual lambs
and (b) lamb production per ha per day. (from Bircham 1981)

122

Growth/Main Tiller (mg/day)

REFERENCES

Arosteguy, J. C.

1982. The dynamics of herbage production and utilization
in swards grazed by cattle and sheep. Ph.D. Thesis
University of Edinburgh.

Bircham, J. S.

1981. Herbage growth and utilization under continuous

stocking management. Ph.D. Thesis. University of
Ed inburgh .

Bircham, J. S. and Hodgson, J.

1983.

Dynamics of herbage growth and senescence in a mixed
specie species temperate sward continuously grazed
by sheep. Proc Proc. 14th int. Grassld Congr.,
Lexington, USA (pp. 601603).

In press; a. The influence of sward condition on rates of
herbage growth and senescence under continuous
stocking management. Grass and Forage Science.

In press; b. The effects of change in herbage mass on

Brougham,

1959.

herbage growth and senescence in mixed swards.

Grass and Forage Science.

R. W.

The effects of frequency and intensity of grazing on
the productivity of a pasture of short rotation rye-
grass and red and white clover. New Zealand Journal
of Agricultural Research, 2, 1232-1248.

1960.

The effects of frequent hard grazings at different
times on the productivity and species yields of a
grass-clover pasture. New Zealand Journal of
Agricultural Research, 3, 125-136.

Davidson, J. L.

1969. Growth of grazed plants. Proceedings of the

Eadie, J.
1967.

Australian Grassland Conference, 2, 125-137.

The nutrition of grazing hill sheep; utilization of
hill pastures. H.F.R.0. 4th Report. 1964-1967,
38-45.

1970.

Hill sheep production systems development.

H.F.R.0. 5th Report. 1967-1970, 70-87.

Floate, M. J. S

1970.

Mineralization of nitrogen and phosphorus from or-
ganic materials of plant and animal origin and its
significance in the nutrient cycle in grazed upland
and hill soils. Journal of the British Grassland

Society, 25, 295-302.

Forbes, T. D. A.

1982. Ingestive behaviour and diet selection in grazing
cattle and sheep. Ph.D. Thesis. University of
Edinburgh.

Grant, Sheila A., Barthram, G. T., Lamb, W. I. C. and Milne,
J. A. 1978. Effect of season and level of grazing on the
utilization of heather by sheep. I. Responses of
the sward. Journal of the British Grassland Soci-

123

ety, 33, 289-300.

Grant, S. A., King, J. , Barthram, G. T. and Torvell, L.

1981; a. Components of regrowth in grazed and cut Lol ium
perenne swards. Grass and Forage Science 36, 155-
168^

1981; b. Responses of tiller populations to variation in

grazing management in continuously stocked swards as
affected by time of year. In Wright C.E. ed.

Plant Physiology and Herbage Production Occa-
sional Symposium No. 13, 81-84, British Grass-
land Society, Hurley.

Hill Farming Research Organization

1979. Science and Hill Farming. Hill Farming Research
Organization, Penicuik, pp. 136-148.

1981. Hill Farming Research Organization Biennial Report
1979-81.

Hodgson, J. and Wade, M. H.

1978. Grazing management and herbage production. Proceed-
ings of the British Grassland Society Winter Meet-
ing, 1978, pp .

1.1-1.12.

Holding, A. J. and King, J.

1963. The effectiveness of indigenous populations of
Rhizobium trifolii in relation to soil factors.
Plants and Soils 18, 191-198.

Jameson, D. A.

1963. Responses of individual plants to harvesting. The
Botanical Review, 29, 552-594.

Milne, J. A., Bagley, L. and Grant, Sheila A.

1979. Effect of season and level of utilization of heather
by sheep. 2. Diet selection and intake by sheep.
Grass and Forage Science, 34, 45-53.

Newbould, P. and Haystead, A.

1978. Trifolium repens (White clover): its role, estab-
lishment and maintenance in hill pastures.

H.F.R.O. 7th Report 1974-1977, 49-68.

Nicholson, I. A.

1967. The grazing animal in vegetational control.

H.F.R.O. 4™ Report, 1964-1967, 46-50.

Singer, M., Holding, A. J. and King, J.

1964. The response of Trifolium repens to inocula contain-
ing varying proportions of effective and ineffective
Rhizobia. Transactions of the 8^b International
Congress of Soil Science., Bucharest, 3, 1021-1025.

ACKNOWLEDGMENTS

I would like to thank all the members of the Hill Farming

Research Organization for their help and advice during the

course of my stay there and particularly the director Mr. John

Eadie, Dr. John Hodgson, Miss S. A. Grant, Mr. R. H. Armstrong

and Mr. M. M. Beattie.

124

CONTRIBUTORS

Bashaw, E. C. , research geneticist. Crop Genetics and

Improvement Research Unit, Agricultural Research Service,
U.S. Department of Agriculture, Room 337A, Soil and Crop
Sciences Department, Texas A&M University, College
Station, TX 77843

Burson, Byron L., research geneticist. Forage Improvement
Research Unit, Agricultural Research Service, U.S.
Department of Agriculture, P.0. Box 748, Temple, TX 76301

Burton, Glenn W. , research geneticist. Forage and Turf Research
Unit, Agricultural Research Service, U.S. Department of
Agriculture, Georgia Coastal Plain Experiment Station,
Tifton, GA 31793

Caddel, J. L., associate professor. Agronomy Department,
Oklahoma State University, Stillwater, OK 74078

Clark, David A., research animal scientist. Grassland Division,
Department of Scientific and Industrial Research, Private
Bag, Palmerston North, New Zealand

Coleman, S. W. , research animal scientist. Beef Cattle Research
Unit, Agricultural Research Service, U.S. Department of
Agriculture, P.0. Box 1199, El Reno, OK 73036

Cuperus , Gerrit W. , IPM specialist. Entomology Department,
Oklahoma State University, Stillwater, OK 74078

Ely, D. G., professor. Animal Science Department, University of
Kentucky, Lexington, KY 40506

Forbes, Thomas David Alexander, research associate. Animal

Science Department, Oklahoma State University, El Reno, OK
73036

Forwood, J. R. , research agronomist. Crop Production Research
Unit, Agricultural Research Service, U.S. Department of
Agriculture, Department of Agronomy, University of
Missouri, Columbia, MO 65211

Glenn, B. P. , research animal scientist. Ruminant Nutrition

Laboratory, Agricultural Research Service, U.S. Department
of Agriculture, Building 200, BARC-East, Beltsville, MD
20705

Godley, W. C., director. Agricultural Experiment Station,
Clemson University, Clemson, SC 29631

Hoveland, Carl S., professor. Agronomy Department, University
of Georgia, Athens, GA 30602

Johns, C. W. , graduate assistant. Soil and Crop Sciences

Department, Texas A&M University, College Station, TX
77843

125

Jordan, Wayne R. , assistant professor, Temple-Blackland

Research Center, Texas A&M University, Temple, TX 76501
Knight, William E. , supervisory research agronomist. Forage
Research Unit, Crop Science Research Laboratory,
Agricultural Research Service, U.S. Department of
Agriculture, P.0. Box 272, Mississippi State, MS 39762
Lambert, M. Greg, research agronomist. Grasslands Division,

Department of Scientific and Industrial Research, Private
Bag, Palmerston North, New Zealand
Lippke, H. , associate professor, Texas A&M University,
Agricultural Research Station, Angleton, TX 77515
McMurphy, W. E. , professor. Agronomy Department, Oklahoma State
University, Stillwater, OK 74078
Martz, F. A., professor. Dairy Science Department, University
of Missouri, Columbia, MO 65211
Matches, A. G. , professor, Texas Tech University, Lubbock, TX
79406 (formerly with the Agricultural Research Service,
U.S. Department of Agriculture)

Monson, Warren G. , research agronomist. Forage and Turf
Research Unit, Agricultural Research Service, U.S.
Department of Agriculture, Georgia Coastal Plain
Experiment Station, Tifton, GA 31793
Pederson, Gary A., research geneticist, Forage Research Unit,
Crop Science Research Laboratory, Agricultural Research
Service, U.S. Department of Agriculture, Box 272,
Mississippi State, MS 39762

Rommann, L. M. , professor. Agronomy Department, Oklahoma State
University, Stillwater, OK 74078
Santelmann, P. W. , head, Agronomy Department, Oklahoma State
University, Stillwater, OK 74078
Sims, P. L., research leader. Southern Great Plains Field

Station, Agricultural Research Service, U.S. department of
Agriculture, Woodward, OK 73801
Sleper, D. A., associate professor. Department of Agronomy,
University of Missouri, Columbia, MO 65211
Taliaferro, C. M. , professor. Agronomy Department, Oklahoma
State University, Stillwater, OK 74078
Totusek, Robert, head. Animal Science Department, Oklahoma
State University, Stillwater, OK 74078
Voigt, Paul W. , supervisory research geneticist. Forage

Improvement Research Unit, Agricultural Research Service,
U.S. Department of Agriculture, P.0. Box 748, Temple, TX
76501

Ward, Clement E. , associate professor. Department of

Agricultural Services, Oklahoma State University,
Stillwater, OK 74078

White, Harlan E. , extension specialist. Department of Agronomy,
Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061

126

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