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In cooperation with the Si'RE, Pennsylvania State College / FEE ALB Ea G
DEPARTMENT BULLETIN No-1281__
Washington, D. C. ; Vv December, 1924
PB, Y
RELATIVE UTILIZATION OF ENERGY IN MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS
By
J. AUGUST FRIES, Assistant Director, WINFRED WAITE BRAMAN and DONALD C. COCHRANE, Associates in Animal Nutrition, Institute of Animal Nutrition of Pennsylvania State College
CONTENTS.
Page
General Scheme for Experiments on Milk Production . . . Apparent Digestibility of Rations by Improved Method . . . Changes in Technic The Respiratory Gases Pian of the Experiments Correction for Milker Animals The Nitrogen and Carbon Balance
Metabolizable Energy
Heat Emission The Respiration Calorimeter Heat Production Preparation of Feed and Feces Samples for Analysis . . . . Net Energy of Feed for Body Gain and Milk Production . . Methods of Analysis “* Drying-up ” Period Live Weights and Rations Effect of Advance in Lactation Composition of Feed and Feces Standing and Lying Apparent Digestibility Summary Hair and Scurf Removed by Brushing Literature Cited
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UNITED STATES DEPARTMENT OF AGRICULTURE
In Cooperation with the SET Pennsylvania State College
DEPARTMENT BULLETIN No. 1281
Washington, D. C. December 19, 1924
RELATIVE UTILIZATION OF ENERGY IN MILK PRODUCTION AND : BODY INCREASE OF DAIRY COWS
By J. Auaust FRiks, Assistant Director, WINFRED WAITE BRAMAN and DONALD C. CocHRANE, Associates in Animal Nutrition, Institute of Animal Nutrition of Pennsylvania State College
CONTENTS Page Page General scheme for experiments on milk pro- Apparent digestibility of rations by improved
GUCTION Stat eth Ra een eee ee ae 2 method. 25 5 = See ee a @hanpesmnitechnichs Wee ee 3 | ‘Lhe:respiratory gases: 2555. s- ee 14 Plan of the experiments: 222). 32s seek ce 4.) Correction formilker = -- <2 yee ee ae 14 DTTC Le Ses EY 28 eee ee ee oe es 5 | The nitrogen and carbon balamce-_______-_____- 15 LESNAR YO Reps ae: ae, ie ia a att eh lea 5-| Metabolizable energy 2.2 at eiie 2 foe 15 Digestion experiments. he. 28 ed) EVE 6 | bleatiemission ace 28 wel + gee Be 20 The respiration calorimeter____...__..-___-__-_- MaipELeat DFOGUCHION= 222 lice tees ee apes 22 Preparation of feed and feces samples for an- Net energy of feed for body gain and milk pro-
REV SISSS bee Ret OER Gy eel Se Ey Skee. Ree 8 Guction! 2227 BLE E Osert fy Reet rhe reere pe WMethods of analysist! 207 ies Br Siti Dryingaup* period. 4.25. = fe) eee Ss 28 Live weights and rations____________-___--___- 9 | Effect of advance in lactation____._.__.-..____- 30 Composition of feed and feces_____2____-____-_- 9 | (standing and lyinp >). eee eee 30 Aspparent GizestibMity=.- 222222 22= eee ak 10;s) "Summary 2.22008! Okey is Saas ee pee ee a 32 Hair and scurf removed by brushing__________ Lise) ahiteratyre Cited“ -- 205 Fe a PR ee 33 WET ee) a NE Re Bee send Ib ABDONGIK. 2 oe Soe oe Se ne 34 IVES EH ATOM ee oe bane. | as Pee ee 12
This bulletin covers the first of a series of cooperative experiments ' with the respiration calorimeter on the metabolism of dairy cows, in accordance with an agreement between the Dairy Division, Bu- reau of Animal Industry, United States Department of Agriculture, and the Institute of Animal Nutrition of the Pennsylvania State College, and as recorded in the program of work of the department for the fiscal year 1915-16. Previous work with the respiration calorimeter had been with steers, and although much remains to be done in connection with the fundamental problems of feeding for meat production, the increasing importance of the dairy industry of the United States led the late H. P. Armsby, then Director of the Institute of Animal Nutrition, to plan this series of experiments with milk cows. ‘
In connection with this report of the first experiment the general scheme as outlined by Director Armsby is given in full as follows. Although changes in experimental procedure have been made as our knowledge of the problem has increased, the project plan has been
1 To Director H. P. Armsby belongs the credit for the planning and inception of the experimental pro- gram. For the execution of the plan of experiment the responsibility rested largely with the senior writers but the success of this venture was in no small measure due to the faithful work of K. K. Jones, J. W. Park, J. E. Mensching, J. E. Isenberg, and E. W. Schmidt, and to other members of the staff of the institute, who assisted the writers in various capacities. EG staf
The writers also desire to express their appreciation to E. B. Forbes, director of the institute, for his kindly criticism and suggestions which have been invaluable in the preparation of these data for publication.
1
2 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
followed faithfully during the entire series of experiments extending over a period of seven years.
GENERAL SCHEME FOR EXPERIMENTS WITH RESPIRATION CALORIMETER ON MILK PRODUCTION
Animals to be used.—Since considerable work on cattle has already been done with the respiration calorimeter, and since cows constitute the commercial source Of milk, it would be most desirable to experiment with those animals: If, however, this is deemed impracticable, because of the difficulty involved in the satisfactory collection of the excreta of cows, necessitating the employment of watchmen at very considerable expense, it is thought that milk goats will, on the whole, be fairly satisfactory as experimental animals, at least for pre- liminary investigations. If they are used it is proposed to employ a form of metabolism cage devised by Bowes, which permits the separation and collection of the feces and urine with comparatively little oversight.
General problem.—lIt is proposed to determine the total energy of the feed con- sumed by milking animals, the losses of energy in the excreta, the expenditure of energy consequent upon the consumption of feed, and, by difference, the net energy of the feed, in the same general manner as in experiments on steers. Furthermore, however, it is proposed to determine the distribution of this net energy of the feed between the two possible forms of production, viz, fattening, or milk secretion, and the effect upon it of the quantity of the feed as well as of other factors.
Lines of experiment.—The following general lines of experimental work are outlined:
1. To determine the maintenance requirement of the dry animal.
2. Feed a moderate ration and, by means of successive respiration-calorimeter experiments, trace the variations in the distribution of net energy between milk production and body gain with advancing lactation. In this way, it is hoped to determine the quantitative relation between the two forms of production.
3. Study the effect of varying amounts of the same combination of feeding stuffs in increasing the milk production on the one hand and the body gain of the animal on the other hand.
4, Study the effect upon milk production and body gain of substituting protein for carbohydrates or vice versa in rations otherwise identical.
SCHEME FOR EXPERIMENTS WITH DAIRY COWS
Later Director Armsby prepared the following outline:
The general problem proposed is to determine in terms of energy the efficiency of the cow as a mechanism for converting feeding stuffs into milk.
The efficiency here considered is what may be called the net efficiency; that is, the percentage of the amount of feed energy supplied in excess of that required for maintenance which is recovered in the milk. The net efficiency, as thus defined, constitutes one of the factors of the economic efficiency, but the latter necessarily varies with the proportion of the total feed which is available for productive purposes. Otherwise expressed, the problem is to determine the net energy values of feeding stuffs for milk production. This problem might be attacked in two ways.
1. By the direct determination of the net energy values of single feeding stuffs by substantially the methods used in previous investigations upon beef produc- tion. This method, however, would be somewhat tedious and would involve more or less correction of the results, upon the basis of average figures, for any fattening of the animals which might occur.
2. By determining upon identical animals the relative availability of the energy of one or a few standard feed mixtures for fattening, on the one hand, and for milk production on the other, and applying the ratio thus determined to the data already available for utilization in fattening.
The second of these two methods appears to promise more immediate, even if somewhat approximate results, and is the method which it is proposed to follow.
The general plan is to make in a first season two or three respiration-calorim- eter experiments upon dry cows receiving different amounts of the standard feed mixture by a comparison of which the maintenance requirements and the net utilization in fattening by the individual animals may be determined.
Incidentally the basal katabolism of the animals as computed by a comparison of the two periods on different amounts of feed is to be compared with katabolism
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 3
as measured directly by the heat production after a longer or shorter period of fasting in order to ascertain whether it is possible to determine the basal katabo- lism of cattle by a single determination of the heat production in what corresponds to the ‘‘post-resorptive”’ state in man.
Then, in a second season, two or three respiration experiments are to be made upon the same cows when in milk at different stages of lactation and on different amounts of the standard feed mixture. From the results is to be computed the utilization of the energy remaining for milk production after the demands for maintenance and for any fattening which may occur have been allowed for on the basis of the results obtained upon that identical animal during the first season.
Circumstances beyond the control of the writers prevented taking up the experimental work in the order outlined, and the experiment here reported takes up only the second problem under the head, ‘Lines of Experiment,’ ‘Feed a moderate ration and by means of successive respiration-calorimeter experiments trace the variations in the distribution of net energy between milk production and body gain with advancing lactation. In this way it is hoped to determine the quantitative relation between the two forms of production.”
CHANGES IN TECHNIC
Before the experiments with cows could be outlined in detail a number of problems involving changes in the technic of he former steer experiments had to be studied. The main question, of course, involved a separate collection of the feces and urine in order that the digestibility of the ration might be determined. The method of milking the animal while in the respiration calorimeter and the collec- tion of the excreta in that apparatus also confronted the writers.
Various devices for the automatic separation of urine from feces in the digestion stalls were tested and discarded, and it was necessary to depend upon a watchman stationed behind the animals.
The problem of milking likewise could not be solved by any apparatus; and since reconstruction of the respiration calorimeter was out of the question, it was necessary to have a man enter the chamber to attend to the milking and to apply the necessary corrections to the ventilation and to the heat as measured.
The third problem, and perhaps the most perplexing, was to provide a means for the collection of the excreta in tte respiration calorimeter. Since in this apparatus the feces and urine can not be allowed to drop on the floor, or remain exposed to the ventilating air current, it 1s necessary to use a duct to direct the excreta into a proper receptacle. This duct must of necessity be comparatively light and comfortable for the wearer in order that the animal may lie down and get up without difficulty; it must not press upon the udder or milk veins or interfere with the milking; and it must fit closely so as not to be disarranged by the movement of the animal. One of he writers - se devised and made the ducts, a description and sketch of which ollows.
The shape and method of attachment of the duct for collecting the excreta are illustrated in Figure 1. The duct was made of heavy muslin, which was reenforced at the top edge of the side flaps along the back with leather straps, and at the lower edge by a double hem. It weighed about 1.9 kilograms, and the entire collecting apparatus, including collar and attaching straps, weighed 5.9 kilograms. At B is a ring, 8 inches in diameter and three-fourths inch wide made of steel clock spring. To this ring the upper and lower portions of the
4 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
muslin are securely fastened. From & the duct is 7 inches in diam- eter practically all the way down to the end. A second ring, 7 inches in diameter, made of a somewhat lighter clock spring, is placed about 25 inches below B at D. Attached to this latter ring are several small rings to which stays may be fastened. As indicated in the sketch, from A to Cis a slit so that A C B forms a flap of the muslin. The two side flaps are held together over the back by short
leather straps by which the openings may also be regulated to con-
form to the shape of the animal. From A to £ and down to the ring B the duct is enlarged to such shape and size that the tail, which is kept within the duct, can be raised during the voiding of the excreta. The side flaps A C B start on B about 6 inches apart and by means of these the ring and duct are held against the body at a place where they do not interfere with the defecation or movements a the animal and which permit the urine and feces to be conducted without loss.
Fic. 1—Duct in position on cow.
This duct will remain in place on the animal without using straps between the legs. The duct received a coating of linseed oil to make it waterproof. This waterproofing failed to satisfy the requirements, and in subsequent experiments a loose lining of thin waterproof “stork sheeting’? was used. With this modification the duct has been very satisfactory.
PLAN OF THE EXPERIMENTS
The general plan for the experiments with cows was the same as that followed in the experiments with steers, namely, to feed a given ration for a definite length of time, not less than three weeks, this time being divided into a preliminary feeding period and the so- called digestion period, usually of nine days’ duration, during which the aaibie excreta as well as the milk were collected for analysis. The animals were watered daily as soon as they had eaten the morn-
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 5
ing feed. The work was carried on by the aid of the respiration calorimeter, and at some time during the last 10 days of each period, the animal was placed in this apparatus so that CO,, CH,, and O, as well as the heat given off by the animal might be measured.
TABLE 1.—Amounts of feeds and dates of periods
Daily feed Dates of the periods Cow No. Period a i NG z ‘ eeding alorim- | Collection of urine Hay Grain begun | eter test and feces g. KQ. J 3. 280 4,900 Jan. 12] Jan. 14-22. (1831 ea Re PE EE one |e ee Oe II 3. 280 4.900 |r>Dece. 8 |{Mar. 8 | Mar. 10-18. Ill 3. 280 4. 900 Apr. 19 | Apr. 21-29. it 3. 364 5. 080 Feb. 9 | Feb. 11-19. (13) Ua St Ee SI oa a ke A 3. 364 5.080 |7-Dec. 8 |4Mar. 22 | Mar. 24-Apr. 1. III 3. 364 5. 080 May 3} May 5-13. 579__ { I 3.730 | 5.590 Van o4 |fFeb. 23 | Feb. 25-Mar. 4. NT iter TEA WaT ue ar Te II 3. 730 5. 590 2 wa RAG 0; |e apiaialo.
ANIMALS
The subjects of this experiment were of quiet disposition and fair productive capacity. The choice of these particular individuals was determined in large part by the fact that they were free from tuber- culosis, the general presence of this disease having been discovered in the college herd not long before the beginning of this research. After the conclusion of the tests here reported these cows also became tuber- culous, and were sacrificed before the maintenance requirements could be determined. The three cows were numbered 579, 615, and 631 and are so designated throughout this bulletin.
Cow No. 579 was a grade of seven-eighths Guernsey blood, born November 7, 1911. Her first calf was dropped on October 5, 1914, and her second on November 25, 1915. She was not bred after the second calving.
Cow No. 615 was also a grade of fifteen-sixteenths Guernsey blood, born October 22, 1912. She aborted with her first calf May 1, 1915, and with her second calf (a 2-months fetus) February 20, 1916.
Cow No. 631 was a grade Jersey, bought with age and breedin unknown, and supposed to have been dropped in 1906. She calve April 11, 1915, and was due to calve again about May 27, 1916.
RATIONS
All the animals were fed rations consisting of the same feeding stuffs mixed in the same proportions throughout the experiment. The quantity for each animal was adjusted so as to be sufficient at the outset to support milk production but not to cause any consider- able gain of body tissue, and remained unchanged throughout the experiment. It was anticipated that as the milk production decreased with advance in the period of lactation the surplus feed would be utilized for body gain in place of milk, thus affording a means of comparing the relative utilization of the feed for the two purposes. To insure complete consumption a minimum ratio of hay to grain was fed. The ration fed was identical with that in use at the same time in the dairy husbandry department of the college, the grain mixture being composed of wheat bran, yellow corn meal, ground
ppp ee eee eee eee eee
6 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
oats, and old-process linseed meal, all of good quality. The hay was average quality alfalfa grown in Colorado, nicely cured, fairly uniform in color, and contained a normal proportion of leaves.
The hay was cut into inch lengths by means of a silage cutter, with the blower removed to prevent the loss of the finer leaf particles. This cut hay was spread in a uniform layer on a barn floor, and care- fully shoveled over a few times, taking special pains to distribute the
fine material with the coarse as evenly as possible. It was afterwards
transferred to large sacks and placed in a storage bin.
The hay was weighed out for 14 days at a time including the diges- tion period, and when possible for more than one animal at the same time. A sufficient quantity of the cut hay was carefully mixed on the loft floor, the quantity for each feed weighed in a metal receptacle, transferred to dust-proof cotton bags, and stored until needed.
The sample for chemical analysis was prepared from small amounts withdrawn at each weighing. When the weighing of the rations was completed this sample material was chopped finer in a meat chopper, then carefully mixed and quartered. This process of mixing an reduction was repeated until a sample of the desired size was obtained.
The sample was then taken to the laboratory for air-drying and grinding. The finely ground air-dry samples were kept in glass- stoppered jars which, as a precaution against moisture change, were sealed with soft wax.
The grain mixture consisted of:
Wheatibrant #144 peu Sarria Ot gatas sige) frags pyalae 300 (SrOWNG AOD US ak Sass Nes eink Wea ee tg a a 300 Corn mie es ee ei cag ee De OS a 300 Teinseed amen, (old process) ese os ee 2 ee 100
To each 1,000 parts of this mixture were added 2.22 parts of dairy salt. From this mixture the feeds were weighed out for the pre- liminary periods. For the digestion periods and for the five ed preceding them, the feeds were weighed out from the separate com- ponents and 5 grams of fine dairy salt were added to each of the half-
day rations. DIGESTION EXPERIMENTS
The ration of each cow remained unchanged throughout the whole investigation. The papas for cow No. 631 was 148 days; for No. 615, 157 days; and for No. 579, 82 days. i
The spacing of the digestion experiments was fixed by the time of the respiration-calorimeter tests which could be carried on only bi- weekly. During these respiration-calorimeter tests the urine and feces could not be collected separately; therefore, in this experiment, the calorimeter test was followed by a 9-day period for the separate collection of the urine and feces.
For this collection of excreta the animal was taken to the dairy barn where the excreta were collected by a man stationed behind the
animals. WEIGHING AND SAMPLING EXCRETA
Each voiding of urine was transferred to a 20-liter bottle, and of feces to a covered galvanized-iron box. At the end of each 24 hours the excreta were weighed. The urine was then well mixed and a sufficient quantity taken to the laboratory for the making up of the 9-day composite sample as well as for certain determinations made on the fresh daily sample. The aliquot weighed out daily for the
hon fer.
‘
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS vf
composite was one-twentieth of the total, and was preserved by the addition of chloroform to the storage bottle. The feces were weighed, immediately dumped on a large zinc-covered mixing board, mixed quickly, quartered, and sampled, the sample being placed in covered cans ‘uhidh were taken to the laboratory for the preparation of the composite samples. These composite samples were made up of one- fortieth of the total feces, and were kept in duplicate in covered zinc cans of about 3 liters capacity. The ld was made air-tight by a broad rubber band over the crack, and a few drops of carbon bisul- phide were added from time to time as a preservative.
WEIGHING AND SAMPLING MILK
The milk, after weighing, was well mixed by pouring from one bucket to another. A sample was preserved by the addition of 1 ~ cubic centimeter of 40 per cent formalin per liter.
The morning milk was combined with the evening milk in the pro- portion of their respective weights to form the daily sample. From these daily samples the aliquots for the composites were weighed out, one twenty-fifth of the total being so preserved. The composite samples were weighed out in duplicate. A separate portion of each of the daily milk samples was kept for nitrogen estimations. All weights of urine, feces, and milk were taken on scales weighing ac-
curately to within 5 grams. The aliquots were weighed on balances |
accurate to within 0.01 gram.
THE RESPIRATION CALORIMETER
Apparatus.—The respiration calorimeter, as its name implies, is an apparatus for the measurement of the animal respiratory products and the heat emission. This particular apparatus is an open-circuit Atwater and Rosa respiration calorimeter modified so as to be suit- able for work with cattle instead of men. A detailed description of its construction and operation has been published by Atwater and Benedict (1)? and by Armsby (2). It consists of a copper-lined cham- ber containing a comfortable stall large enough for a medium-sized cow, the animal being able to lie down or stand at will.
Gases.—The doors close tight against rubber gaskets and the ven- tilation is maintained by means of a pump which draws a constant current of air through the chamber and measures the volume at the same time. This ventilating air current is sampled and analyzed as it enters and leaves the chamber and in this way the gases added by the animal are determined.
Heat.—The heat removal and measurement are accomplished by means of a current of cold water circulating through a coil of copper tubing within the chamber. In this experiment the gas and heat measurement covered 24 hours, subdivided into two 12-hour periods.
Calorimeter period.—The cow was placed in the calorimeter cham- ber at about 1 p.m. At 6p. m. the experiment began, ending the second day following at 6 p.m. While the animal was in the respira- tion calorimeter no attempt was made to keep the urine and feces separate, and the total excreta were weighed and sampled at the end of each 24 hours.
3 Figures in italics in parenthesis refer to Literature Cited, page 33.
8 BULLETIN 1281, U. S. DEPARTMENT OF: AGRICULTURE
Tie weight—The cow was weighed just before entering the respira- tion calorimeter and immediately after leaving it at the end of the experiment.
ced and water—The animals were fed at 6 o’clock morning and evening through a lock trap which is an integral part of the apparatus. After the animal had finished the morning feed, water was offered in a specially constructed basin. The details of these operations have been described in previous publications of the Pennsylvania Institute ~ of Animal Nutrition.
Temperature.—The rectal temperature of the animal was taken with a clinical thermometer about one hour before the beginning of the experiment and also at the end of the experiment.
Milking.—The cow was milked twice daily, at 4.30 morning and evening, by the same person. ‘To accomplish this the main door of the apparatus was opened and closed while the milker stepped into and out of the apparatus. The presence of the man in the chamber necessitates a correction which has been taken into account.
Error due to opening the respiration chamber.—Since the ventila- tion current is drawn through the chamber the loss of gases due to opening the door is less than it would be were the air forced through or were it stationary at normal pressure. However, since the tem-
erature of the air in the chamber 1s usually several degrees centigrade ower than the room air, an outward flow of air naturally takes place at the opening of the doors. This loss can not be very large under these conditions; but, whatever it may be, no correction is applied and the error is carried throughout the experiment.
PREPARATION OF FEED AND FECES SAMPLES FOR ANALYSIS
A sufficient quantity of hay, grain, or feces samples to contain from 1.5 to 2 kilograms of dry matter was weighed out and placed on shallow, galvanized-iron pans and allowed to dry in a steam-heated drying-closet at from 55° to 65° C. When the samples had become thoroughly dry the pans were removed and placed on shelves in the erinding room for several days in order that the material might come to approximately normal moisture content at the room tempera- ture. Just before the grinding, the pans with the samples were weighed and the loss in weight termed “loss on air drying.” The material was then finely ground, being passed through the mill two or more times until the desired degree of fineness was obtained. This finely ground material was allowed to le exposed to the air . until cooled, then carefully mixed, transferred to glass-stoppered bottles, and sealed.
METHODS OF ANALYSIS
On the ground feed and feces samples, the usual feeding-stuff analyses were made; and the heat of combustion was determined by means of a bomb calorimeter. In general, the methods of analysis of the Association of Official Agricultural Chemists have been followed.
In the fresh feces ‘total nitrogen’? was determined by the K6énig method.
In the fresh composite urine the specific gravity, total nitrogen, and carbon were determined. For the energy determination about 5 grams of urine was weighed into a platinum capsule and dried in a
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 9
Hempel desiccator for two days; then a second charge was added and the capsule returned to the Hempel desiccator to remain until dry enough to ignite without the aid of any primingsubstance. The combus- tion in the bomb is complete when 20 atmospheres of oxygen is used.
In the daily composite milk samples of ite intermediate periods, the specific gravity and fat were determined, the latter by the Bab- cock method. Carefully calibrated bottles were used, the measured milk charges being weighed on an analytical balance. In the daily composite milk samples of the digestion and calorimeter periods total nitrogen and fat (by the Babcock method) were determined, and in the composite sample of each period determinations of specific eravity, fat, nitrogen, carbon, and energy were made.
Samples of the daily feces were analyzed for total moisture.
Since this is the first experiment ever reported in which the energy output of the milking animal was directly determined, and since the maintenance requirement of the cows was not determined, such an exhaustive study of the results is not submitted as will be possible when the data of subsequent experiments of this series shall have become available. At present, therefore, the more prominent results only will be pointed out, placing on record the experimental data with the hope that later results may shed additional light on the subject and serve to confirm the conclusions from this study.
LIVE WEIGHTS AND RATIONS
The live weights given in Table 2 are the average of nine daily weighings taken before watering and the same time of the day. At the time of weighing, small amounts of feed were sometimes noticed in the feed box; but these, with a few exceptions, were eaten after the animal had been watered. In the same table is recorded the total weight of daily feed. The feed was divided into two equal por- tions, the grain and hay being fed together at the specified hour.
TABLE 2.—Average daily weights before watering, and weights of daily rations
| Live weight | Daily feed
Cow No. | | Period Period Period | Alfalfa Grain Salt I II Iil | hay mfxture . { Kitograms | Kilograms | Kilograms | Kilograms| Kilograms| Grams Gi rn Reece at pe Po Oe VN ee oe 2 334. 3 | 360. 6 | 390. 4 | . 280 4, 900 10 ifn lis S20 Rie POR. Seed Pe eaee a ee | ee ee oe | 361.8 | 366. 1 368. 9 3. 364 5. 080 10 Gee BBS 3 Pee ee ee eS eee 367. 2 371.8 errr | 3. 730 5. 590 10
Cows 615 and 579 showed a slight tendency to gain in weight with the advance in the lactation period. Cow 631 was about dry in period II and her increase in weight is due in sey to the rapid devel- opment of the fetus at her advanced stage of pregnancy.
COMPOSITION OF FEED AND FECES
The alfalfa hay, grain mixture, and the feces of the various periods were subjected to the customary feeding-stuff analyses, as reported in Table 3. The heat of combustion was also determined, the data being computed to dry matter.
Particular attention is called to the loss of nitrogen on drying the dung by itself. This same loss also occurs in the dung-and-urine
100177—24,——2
10 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
mixture; and for that reason the nitrogen determined on the fresh material by KOnig’s method is used throughout the computations.
APPARENT DIGESTIBILITY
The detailed data used in computing the apparent digestibility of the rations will be found in the appendix. In these tables the salt has been added to the dry matter. The digestion coefficients
of the feed have been collected for comparison, and are recorded —
in Table 4. TABLE 3.—Composition of dry matter of feed and feces | } | Nitro- Pro- | , Dry Non- Total od Energy Sub- | Cow Period; mat- | Ash Bie pro- crude gen- | Ether | nitro- ie Car- per ter filo tein | bon gram
extra Eelaa ses gen
Per Per Per Per Per cent cent cent cent cent
cent cent cent cent cent | Calories oa Tiss. 970] 8.159} 14.713] 2. 698) 27. 609] 44.320] 2.501) 2.928) 2.354 45.748 4,435.77 631, II
Per Per Per Per Per
Alfalfa |} 615; § I1|p89.727| 8.217) 14.069] 2.975) 27. 465 hay___-|] 579 I
I 615 “ foo ue 8. 582} 14.625] 3.177) 27.411
} | 44.725| 2.549} 2.884] 2.251) 45.760, 4,433. 11 43.546) 2.659] 3.016] 2.340) 45. 769] 4,440. 52
87. 556; 4.471) 13.947) .400) 8.187} 68.139) 4.695) 2.465) 2. 380 46. 145) 4, 549. 46 |
86. 675| 4.384) 13.918]. 479) 8. 248] 68,093) 4. 830) 1 2. 477 2.375 46.055) 4, 548. 37 |
: 40. 499} 2.919 = 405 \ L Bs 46. 976| 4, 674. 55
18. 295, 10.707] 11. 781] 1. 208) 32. 886 22. 329 40. 540) 2. 683°5 329) 1. sos) 46. 426) 4, 612. 25
' | | | fss 940 4.370] 13.771] . 653/ 8. 008| 68. 581| 4. 580| 2.489] 2.350 46.002) 4, 544. 67 18. 163) 11. 156] 11. 275| 1.556
|
III} 17. 644) 11.279 11. 963] 1. 053] 32.976) 39.959] 2.770{°> $36/t 1. 914) 46. 423] 4, 601. 24
SS peal Tit 76 s21 10. ob 12.006] . 978/ 32. 106 42. 409 2.455 {°2 aly 1.921] 46. 954) 4, 651. 40
“ae 615, ry} 18.132 10. 043} 10.400] 2. 421| 30. 9431 43. 4951 2. 763 {"> traly 1-664) 46. 969) 4, 644. 12 || ©19) IIT] 17.776 10. 222) 11.994) 926} 33. 900 40. 535) 2. 423 {5 T83|\ 1. 919) 46. 796} 4, 627. 26
==9 | 579, T} 16. 249 10.878) 11.325 1.711] 32.853) 40. 649 2, a4 {°3 272i 1.812| 46.499] 4, 617. 21 579, rT} 16. 404, 10.389] 11.200) 2. =) 33. 102] 40. 787 ari 33) 1.792] 46. 686] 4, 608. 75
1 Average of the other two grain-mixture samples.
2 Nitrogen in fresh feces by K6nig method, computed to dry matter. In the grain mixtures the protein was obtained by multiplying protein-nitrogen by the factor 5.86, and the nonprotein nitrogenous matter by using the factor 4.7. ¢ :
Table 4 shows a very close agreement between the apparent digestibility of dry matter on a percentage basis, and also in terms of energy. Cow 579 shows an apparent digestibility of the ration approximately 2 per cent higher than the other two cows.
e organic matter appears to be about 2.5 per cent more digestible
on a percentage basis than in terms of energy. ‘This difference is
robably due to the fact that the ingredients as determined in the
sae do not have the same composition as those in the feed. This is
especially true of the crude fiber, which has a higher carbon content
in the feces than in the feed. The feces invariably show a higher energy value per gram of dry matter than the feed.
The divergence of the coefficient of digestibility of protein with cow 615, period II, from the average, is unexplained; and since it is accompanied by an abnormally low figure for nonprotein nitrogenous matter it is probably due to some error of work. Both of these figures have been omitted from the average for this animal.
AR Gs pe
| Organic matter | LL Se ee Cow : | Dry In . No. Period | matter Dr terms of Protein | energy matter (calo- ries) | Per cent| Per cent| Per cent| Per cent | ee a | 67.93 | 69.51 66.67 | 73.47 1H fgg Ona ese | 66.80 | 68.59] 65.93 73.19 631__| 11) fh eee 67.52 | 69.26 | 66.75 | 72.45 True aver- | BPO ee 67.42 | 69.12 | 66.45 | 73.04 ESBS ee One ae Give 1) 68750" |) 65499 72526 1S BR Coren eee 67.90 | 69.26 | 66.84 | 176.09 615 TGS eee Gf250 We G8595 cls G6462 4 12542 Js | True aver- | ave-t eas. 67.53 | 68.91 66.48 | 72.34 | TAA GAOL BS 69.65 | 71.20 | 68.88 | 75.38 Pes! Meee ee 69.09 | 70.47 | 68.32 75.47 579__ . True aver- agers 2.55 69.37 | 70.84-| 68.57 | 75.43
1
with other forms of production, or as an excretory product.
‘MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS
11
TABLE 4.—Digestion coefficients (apparent digestibility—feed minus feces)
Omitted from the average.
|
Nitro- Total | Non- | Crude Ether - | igen-free nitro- | Carbon |protein fiber | extract extract gen | | | { | ! | Per ih Ee cent| Per cent| Per cent| Per cent) Per cent 70.80 | 34.20.) 77.77 | 75.36 | 74.06 | 67.19 Go. 520i Se O48 We WOlGn | aisle | OO “66239 79.77 Beet ee OSs ewos 2a. veloc 67.14 72.39 | 33.19 | 77.47 | 76.24 | 72.18 66. 91 75. 66 | 33. 91 76.15 (heey bsiel ESBS aS" 66. 38 147.97 | 38.09 | 76.18 | 77.24 | 73.50 | 67.14 S216 S106 lwo | 79.24 | 70.19 66. 94 | 1 78.91 |. 349863) 76.58 | 78.41 72. 41 66. 82 65.36 | 38.08 | 78.89| 79.85 | 74.99| 69.24 62.64 | 36.01 78.34 | 79.78 | 74.55 68. 57 64.00 | 37.05 | 78.62 | 79.81 | 74.77 68. 90
In Table 5 the figures for the urine represent the average for nine days, except with cows 631 and 579, period I, in which cases the average includes but eight days because of an accident to some of the samples.
HAIR AND SCURF. REMOVED BY BRUSHING
The daily growth and loss of hair plus the epithelial offal, or dandruff, may be considered either as a gain of substance together
Since in
the dairy cow this material is not a desired product, is not accumula- tive on the animal, and can not, like protein and fat, be again meta- bolized as a nutrient either in or out of the animal body, it has seemed wisest to treat it as an excretum. The quantity and com- position of this daily loss are found in Table 6.
MILK
The quantity and composition of the milk are given in Table 7.
TABLE 5.—Average daily excretion of nitrogen, carbon, and energy in urine
Cow No.
Period
|
as Dry
Weight raaitcr! Grams Grams 6, 540. 6 586 7, 536. 0 626 7,141.7 530 6,131.8 §12 6, 860. 4 500 6, 970. 0 393 6, 867. 5 544 7, 685. 1 492
Total | A Organic nitro- | aoe. matter as gen? | energy Grams Grams Calories 105. 41 | 163. 58 1, 583.8 132,33 |. 177. 25: | 51600 117. 98 | 154. 55 Pasty 94.98 | 138.82 1, 323. 4 96. 53 146.47 | 1,409.2 99.70 | 150.55} 1,406.3 101.88 | 151.63 | 1,487.2 112. 14 163.15 1,611.3
1 The dry matter was computed from the charges of urine which were dried sufficiently for the com-
bustion in the bomb calorimeter, but not absolutely iry
7 Average of the total nitrogen in the daily urine.
They are, roughly, 5 per cent high.
12 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
TABLE 6.—Daily weight of hair and scurf removed by brushing
! Dry : Organic Cow No. Period ranieoe Nitrogen} Carbon | matter
| as energy
Grams Grams Grams Calories i 26. 3 1. 88 10. 33 | 110. 08 PS) bis A Oe Ea) TEE eee Re, LE ROOR eee ies es SPU eee ah | II 18.7 1. 34 7. 34 ieePl (ees Ill 22. 4 1. 60 8. 80 93. 75 I PPG 2. 02 9.99 107. 53 TAGS eth a pepe as Peis 37 las Sania Pade t nda ih SS Sabadell a Neh bas 3 | II 20. 6 1. 84 9.06 97. 59 III 18.8 1. 67 8. 27 89. 06 579 { I 16. 5 1. 29 6. 59 70. 24 ~ SST Str a tt igen pang Sar ERT RE BIR BS Til?) | 206 1.61 8. 23 87. 70
Total dry matter not fat has been computed according to the formula:
+0.14
sp. gr.—1.0000 | per cent fat 1000 5 4
To this the addition of the fat gives the total dry matter in the milk.
METHANE
The combustible gases eaeapms from the animal were determined in a continuous sample of air from the respiration-calorimeter cham- ber, which was first freed from carbon dioxide and water and then passed through a combustion tube, where by means of red-hot plati- nized kaolin the combustible gases were oxidized. The water and carbon dioxide thus formed were absorbed and weighed and from the weight of the carbon dioxide the methane was computed. The water determination, because of the long tubes and many rubber connections in the apparatus, is not considered so accurate as that of the carbon dioxide. The grams of methane per 100 grams of digestible carbohydrates (feed minus feces) have been computed, and ieee together with the other values for methane are recorded in
able 8.
In view of the fact that methane is a product of fermentation, the total quantity in the separate periods as well as the amount per 100 erams of digested carbohydrates was found to be remarkably uniform. The average amount per 100 grams of digestible carbohydrates for the eight periods of this experiment was 5.02 grams, whereas 4.5 is the general average from a large number of experiments made here and in Europe. The average amount of methane per day for the eight periods was 191.84 grams, or 267.6 liters under standard conditions.
TABLE 7.—Amount, composition, and energy value of the daily milk
| | | t | Specific | Fat Dry Crude Total gravity | matter ash nitrogen
Total | Energy carbon value
Cow No. |} Period | Weigh
| : Grams Grams | Grams Grams Grams Grams Grams Calories S 3. ab
631 I | 5,902.5} 1.0332 | 335. 3 900. 7 | 4 38. 3 483.9 5, 378. 2 =. 2 ior Il 812.8 1. 0354 43.3 125. 1 7.8 6.8 70. 1 784, 1 T 97,227. 2 |i 21. 03828 334.6 | 1,004.6 | 46. 7 44. 6 542.4 6, 020. 0 015... TL |}: 7272.8 |xewd..0384 | 352.7 | 1,040.7 | 47.8 47.1 556. 7 6, 278. 7 III | 7,195.0 1. 0332 | 343.2} 1,018.8 | 46. 7 46.3 550. 8 6, 157.0 579 I| 8,371.1] 1.0330 401.8 | 1,184.5 53.8 49.2 630.6 | 7,023.6 ents II | 8,096.7 | 1.0331 | 383.0] 1,140.8 51.7 49. 4 598.3 | 6,749.5
|
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 13
TABLE 8.—Daily production of methane
: CH, computed from com- Combustible gases bustible gaseous carbon Cow No. Period Per 100 CO2 by | Carbon grams | Energy com- equiva- Total | digestible} equiv- bustion alent carbo- alent hydrates Gram .Grams Grams Grams Calories | I 540. 45 147. 38 196. 94 5.36 | 2, 627. 97 Golem eee, 02S ORE A hin ea! ike II 518. 77 141. 46 189. 04 5. 23 25522500 Til 497. 61 135. 70 181. 32 5. 02 2, 419. 53 I 494. 50 134. 85 180. 20 4, 84 2, 404. 59 Gi eee SO pe ok me be al Leh IL 497. 69 135. 72 181. 36 4.81 2, 420. 07 Iil 505. 37 137. 82 184. 15 4.96 2, 457. 30 579 { I 574. 20 156. 58 209. 23 4.90 | 2,791.96 GeCGEI Lhe tie ee II 583. 08 159. 00 212. 47 5.06 | 2,835. 20
APPARENT DIGESTIBILTIY OF RATIONS BY IMPROVED METHOD
The digestible portion of a feeding stuff is that portion which in passing through the aliméntary tract is resorbed, and thereby becomes available for the maintenance of the functions of the ease
ecause of the difficulty of determining true digestibility, however, it has been customary to ascribe to a feed a much higher digestibility than it really has; for, by using the prevailing method of computation which assumes that feed constituents minus feces constituents equal digestible constituents, a part of the feed which is neither resorbable nor useful is included with the digestible. It is a well-known fact that ordinary feeding stuffs for cattle contain ingredients which would be altogether useless for the support of the vital functions of the animal organisms were it not for the presence and activity of microorganisms in the alimentary tract. though because of such activity, a certain amount of material is converted into substances useful to the body, a considerable part of the original feed substance is changed into forms which can not support the physiological require- ments of the animal. It has been customary to consider these useless substances as digestible matter. This gives too high a figure for es eae digestibility. Since the quantity of methane and its equi- valent energy can be determined, and since the heat of fermentation of the organisms which liberate the methane can be estimated with a fair degree of accuracy, it is possible to exclude these factors from considerations of apparent digestibility, thus arriving at a closer approximation of true digestibility.
n Table 5 only the visible portions of the excreta have been con- _ sidered. However, the excreted useless portion of the feed contains gases as well assolids. It is therefore consistent to include the useless gases with the feces and compute the digestibility as has been sug- gested (Fries) (3) by using the following values: Methane, equivalent to 13,344 calories per gram; ratio of methane to carbon dioxid in the products of fermentation in the alimentary tract, 1 to 3.2 by volume; and heat of fermentation equal to 2,000 calories pat gram of carbon dioxide produced. The apparent digestibility thus computed will approach the metabolizable and the net values, and hence will be a more accurate expression of nutritive value than will a figure derived, -as usual, by a method which fails to consider the important factor of gaseous losses.
14 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
Since in the work reported methane is quantitatively determined, whereas the values for carbon dioxide and heat of fermentation are estimated, the digestibility of the rations in this experiment has been computed, (1) on the usual basis of feed constituents minus feces constituents, (2) by considering methane as indigestible, and (8) by taking account also of loss of feed energy through the heat of fermenta-
tion. The digestion coefficients as computed by the three methods _
can be compared by reference to Table 9. In the preparation of Table 9 the factors used and the method of computation were as follows: 1 liter of methane—0.7168 grams. 1 liter of carbon dioxide—1.9652 grams.
Ratio of methane to carbon dioxide (in fermentation gases) 1: 3.2. Scheme of computation:
Grams methane ______ liters methane ______ liters of carbon dioxide equivalent to the carbon dioxide of fermentation, or grams methane X 17,546—calories due to fermentation _________-_ grams carbon dioxide
eae ae yey energy equivalent (calories).
TABLE 9.—Apparent digestibility of dry matter. interms of energy, computed by three different methods
Coefficients computed by | Dry matter digested per day as three methods energy—
3 . : CHsg and Esti- Cow No. Period eee ee eatin SARS : z fermenta-| Method 1} Method 3! heat of minus added ti feces | to feces ee Go added tion to feces Per cent | Per cent | Percent | Calories Calories Calories Terris 66. 67 58. 57 47.92 | 21,642.0} 15, 558.4 3, 455. 6 Gai a es A Pe tO Pla os at 65. 93 58. 14 47.89 | 21,338.0/ 15, 498.6 3, 316. 9 |i y Rae 8 66. 75 59. 24 49. 35 21, 488. 7 15, 887. 6 3, 181.5 | eee 65. 99 58. 81 49. 38 22, 114.0 16, 547.6 3, 161.8 OlOte as 5 os ee Se bi) Fee 66. 84 59. 60 50.07 | 22,331.0| 16, 728.9 3, 182. 2 16 0 fo 66. 62 59. 25 49.56 | 22,207.0| 16,519.6 3, 231.1 579 { ey 8 od 68. 83 61. 23 51. 25 25, 303. 6 18, 840. 5 a, Omla2 en ee ie See EES ee 68. 32 60. 61 50.48 | 25,135.9 | 18, 572.7 3, 728. 0
In Table 9 are found side by side two columns (the sixth and seventh from the left) giving the dry matter digested per day ex- pressed in terms of energy and computed according to the old and new methods, also one column giving the daily estimated heat of fermentation for each period. Comparing methods 1 and 3 the digestible dry matter, as energy, is from 16.61 to 18.75 per cent less when the nonusable energy of methane and of heat of fermen- tation is classed with that left in the feces.
THE RESPIRATORY GASES
The respiratory products and gases from all sources are mixed in the outcoming air. The methane as determined comes presumably from a single source; but the carbon dioxide comes from various sources and can not be separated according to origin, the total carbon dioxide therefore representing the metabolism of the cow, of the bacteria of her alimentary tract, and of the man engaged in milking.
CORRECTION FOR MILKER
In respiration-calorimeter experiments with milking cows it is necessary that a man enter the apparatus to do the milking; hence a correction must be applied to the heat emission, and to the water and carbon dioxide as measured. A determination made at the
Pa en
.
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 15
institute of the carbon dioxide given off by the man engaged in milk- ing in the calorimeter gave 1.0275 grams carbon dioxide per minute for a man weighing 66 kilograms. ‘This amount of CO, indicates that the milking of a cow by an experienced milker can be classed as light work in so far as represented by the output of energy and car- bon dioxide. The corrections for the milker which have been used are 0.04327 Calorie, 0.01557 gram CO., and 0.02231 gram H,O per minute per kilogram of body weight. These values were obtained from the average figures recorded by Atwater and Benedict (4) for two men doing work usually for eight hours per day, described as ‘‘more or less severe,’ and as ‘‘reasonable and not at all excessive”’ by reducing their values to correspond to the carbon dioxide found by an actual determination for the man while milking. Twice it was necessary during the calorimeter experiments for a man to enter the calorimeter chamber for a period of less than a minute. ‘This time has been added to the milker’s time and the same correction applied. The total carbon leaving the animal as carbon dioxide is given in
Table 10. THE NITROGEN AND CARBON BALANCE
In order to determine the metabolizable energy it is necessary to correct the urine for gain or loss of nitrogen in the body, hence the need of computing the nitrogen balance. Further, in order to com- pute the percentage recovery of the feed matter and energy in the milk, the gain or loss of body protein and fat must first be determined. This is made possible by having the income and outgo of nitrogen and carbon balanced. From the nitrogen and carbon balances the corresponding gain or loss of protein, fat, and energy are computed. The results of such a balance of nitrogen and carbon are found in Table 11.. The data for the income and outgo of dry matter and the balance of water per day and per head will be found in Tables IV to
VI of the appendix. METABOLIZABLE ENERGY
According to the writers’ definition of metabolism—the total of the chemical changes which the constituents of the resorbed feed undergo in‘the course of their utilization and their conversion into excretory products—metabolizable matter and energy could, generally speaking, pense not only the feed but also such tissues of the body as may be katabolized. However, in connection with studies deal- ing with the principles underlying animal feeding, it is necessary to use the term metabolizable in a more restricted sense.
TABLE 10.—Total carbon dioxide | leaving the animal
As measured Man milking
Cor-
Cow No. Period rected
oe Capen aS CO: Carbon | Energy | carbon
Grams Grams Grams Grams | Calories Grams I 5, 169. 81 1, 409. 80 13.8 3. 87 39. 50 1, 405. 93 Vo hh Sale eg See a ee Sg ee II 5, 529. 05 TOOT ae 10i5 il 3) ial 31.7 1, 504. 66 TOR Celts air cop est Sicha beatey? ye- 40) 9 execs aml bategeyree eae (ee ae 1, 589. 40 1 5, 165. 51 1, 408. 63 18.9 5. 29 53. 97 1, 403. 34 GU as ea yn Mee II 5, 353. 07 1, 459. 78 20. 5 5. 74 58. 54 1, 454. 04 : Ill 5, 469. 35 1, 491. 49 21.9 6. 14 62. 55 1, 485. 35 579 { I 5, 951. 13 1, 622. 87 19.3 5. 41 55. 12 1, 617. 46 ~T ii iaaidasesicidie Wiese en Bae ee II 5, 857. 07 1, 597. 22 220 6. 36 64. 82 1, 590. 86
1 Corrected for carbon dioxide outgo of man entering the colorimeter to milk the cow 2 Factor C in COs, 0.2727.
/
16 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
TABLE 11.—Income and ouigo of nitrogen and carbon per day and per head
| |
Cow 631, period I Cow 631, period II | Cow 631, period IIT Nitrogen | Carbon | Nitrogen Carbon | Nitrogen | Carbon | } S } 2) eo |} | © 2) | © | = o | ig ° gif o = S = oe) Les ilics S = DES = S = S be S iid Ba i ge 2 =) 2 = cS is = 3 2 =) > | 5 Ad od & Bil ee ie ST oH ow & Lo | 45.1 26 }
Alfalfa hay____------- $5.41... 2 1,335. 0)-._..--| 84.9)... [1,346 7)2 oe ee 1,355. Sho! Composite grain__.__ 10 Se fee 7? Mir | sina i} ssp. mmm 1. Soa OL et pCi | 1, ie ee efnsed teed = 25 72 Us) siete hy Be pate 25 s2_ 29 Ctipey ee Bie Ss ee ees Bes @: Geonts i 10.2 LUT ET ee. “aial PO 49 Gira se O87. 41. bo. AL 2s . 100:3 vA a 1, 079.8 i A We eae 105. 4). | 163.6)______ Ee OSes re Ce Aol 353 "154.6 os SPs Pe 7 ae | pple rl Papi ris eee Bee: : Tl Le ee. . 2h) pois =~. 5 | Mead mae 433. Dia" Tip acienal ale ee ee eee wae i 2 eT Ee TTS ee SO oe [Pee Meepry, iy BA 4if enlist aA Shears bor ns oF) Te 21 RP RRE ea Pearce Ce eee Pas eres [cr @> memerl ped fae) | 135.7 Garhen-doside 2+ 7} 2 457.4 Stee Fee 11, 409. 8!_.____- tae fh 533) A SOU 8) 822 2 pe 2282 (ete /1, 589. 4 Difference_.....-....- 4. One| ebewnee }~ 16:2\ -, 60)... eee | 291. 9}... iL | pa 318.2 195. 2; 195. 2:3, 318. 63, 318.6 196.1 196. ar 305. 8 3,305.8 194.1) 194.13, 296. 73, 296. 7 I i 1 i I Cow 615, period I Cow 615, period IT Cow 615, period III | | / Nitrogen Carbon Nitrogen | Carbon | Nitrogen Carbon BA Tsp Rat Psat Pip: (Ove eOUaE: Seer Id sts Z, Bf Bolo of eq elB) b Bl Beeb Bi] Sob Biles So = = Se Le = = = = = = |e] oOo} & } oye poy 4 Oc iresq) ears 3 fons ten opera of oer’. mpenipd ape |Gms.| Gms.| Gms. | Gms. | Gms.| Gms.| Gms. Gms. Gms. Gms.| Gms. | Gms. Jad TUT 1 5 lee tee | Se ae Bos: ede Bee PS 2 6 beg ae 19-2 *? 1 SoG 2 = Composite grain___.- 109. 6|___.-- 2, 052. 4). = -.2 fad: 3 (2. 027. Si. =. 1OB: Teo === 012. 3} 4 Se ee ee ee Ey iy - (aaa ae | j fig: y's 520. ee. Se ee eat 1,125.1 Mane 22 55) toes TS BE Vs GSO Le tae &:. 3. | eee (MSR Sites 146.5 ..._. 99. 7.2.1.2 150.6 DS - Paes ee ee Oj. Fi) y(t | Re a cy. aeests Cy Renee 1S) eee 8.3 i oh ot iad pa a a2) 622 2) Sek ae Oe et 2 ae a eee wr ee 1 ase ie fj Ries SES cape) ee oe ie ty | Serer ees rere ag | Se oot Lo ere SERRE: Pee ae ae ee? | a | ey OPS IP Ge | bea eee se Se Be, et 137.8 Carbon dioxide..._._|...__- [ae [er veed '1, 408. 6)... _- $5.4.858.3 pie. BS TA i eee Be is ABs 1,491.5 Dilferpnee == | a4 EN OAT Be Ae Pi Tyas oy EB
SS OC
| 197.2) 197. 213, 426.9 3, 426.9, 197.4) 197. 4.3, 428.13, 428.1 207.4 207. 43, 464.13, 464.1 | | } | | i |
Cow 579, period I Cow 579, period IT
Nitrogen | Carbon Nitrogen | Carbon
Income | Outgo | Income | Outgo Income | Outgo | Income |
/ | ' /
aCe DG. 5 fa hee ee (PDS Beh ee oe (8 7 LL ee Composite grain. ___- 2102 beet |: eRe Be pe ee 219 6 Er eure rai Ce Rl ee ees pare re have ae 54.0)) oe 0 a oy ace 1, 180.7 Pirate Se er ee eo 150-6 ee 1k Ss el eee 163. 2 Wires 3 a hee sk 1.3) pai US jg 2 eee eee $26 Eee 8&2 LT! iN? Sieur | ap enegSD ¢ 49.21. #2. I (i tia ee eS eee 598. 3 Lee jain epee seem lel ep sey bare open ane ey te ep — Seen) ag G3 bette LT 2 ri) eee Ci ee eee eee (Pee ee ae. et 10, fl 2 See, OMe wes, Sel (Pomc ae ee 159. 0 Carbon dioxide___-___ [5 Ce Te ee Seay Geo i eee eee 1, 597. 2 Bpitewericey 67 Ps ig oy | eee ee ae oY | We 2 ee: LBs ae 55.9
215. 9 | 215. 9 3, 757. 0 3, 757. 0 | 221. 2 221.2! 3,762.5) 3,762.5
The sum of the daily excretions represents a definite amount of energy, and this energy in the last analysis represents feed energy. Hence it is the difference between the gross energy of the feed and
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 17
of the corresponding excretions which alone can be of use to the animal. !
In other words this difference is the portion of the feed energ which can become useful for maintenance (in the more inclusive sense) work, growth, or other constructive metabolism. It is to this difference that the term ‘‘metabolizable energy”? has been given. In the literature this portion of the feed has been variously ce, nated, as available energy (as distinguishable from net available energy), fuel value, physiological heat value, etc. From what has been said it must not be inferred that all this difference, or metaboliza- ble energy of the feed, can be utilized for maintenance (in the nar- rower sense) or production; rather, it is understood that some of this energy must be utilized in the work of digesting the feed, and forming and eliminating the excreta.
Table II shows a somewhat unusual case of a loss of nitrogen ac- companied by a gain of carbon (cow 631, periods J and II). Invall the other experimental periods nitrogen and carbon were either
ained or lost together. This is discussed more fully under gain or fost of body protein and fat. )
The end products of protein destruction in the body contain chemical energy, and in order to eliminate the nitrogen factor in the computation of metabolizable energy the animal body is computed to nitrogen equilibrium by the application of a correction for the gain or loss of body nitrogen. ‘The factor used for this correction is that proposed by Rubner and referred to by Armsby (5); namely 7.45 Calories per gram of nitrogen. This energy is added in the case of gain, and subtracted in the case of nitrogen loss. Thus, a con- siderable part of the gross energy of the feed protein can not be utilized by the organism. This correction of the energy for the daily gain or loss of body nitrogen is found in Table 12:
TABLE 12.—Correction for gain or loss of body nitrogen
Cow | Pe- |Nitrogen| Correc- | Cow Pe- |Nitrogen| Correc- Cow Pe- |Nitrogen| Correc- No. |riod}| gain tion | No. riod} gain tion No. riod} gain tion Grams | Calories Grams | Calories Grams .| Calories I —4,0 —29.8 | I +3.4 > +25.3 579 { if +9.5 +70. 8 a Bee II —6.0 —A44,7 || 615___-_- II — 1:2 A ISESBSOA) Of RER-S-= II +1.8 +13.4 | Tit | +19.3 | -+143.8 || TIT —7.1|; —52.9
GAIN OR LOSS OF BODY PROTEIN AND FAT
Since the glycogen supply of the body does not fluctuate materially under normal conditions of feeding, changes in the nitrogen and carbon of the body may be ascribed to changes in the protein and fat content without appreciable error. From the nitrogen and car- bon balances it is therefore possible to compute the gain or loss of body protein and fat. Whether nitrogen is gained or lost it is con- sidered to be accompanied by such an amount of carbon as is con- tained in an equivalent amount of protein. Thus the gain or loss in fat can be computed from the carbon balance only after the car- ben content of the gain or loss of protein has been set aside. From this it follows that in case there is a utilization of a part of the non- nitrogenous fraction of katabolizing tissue protein the amount so utilized is not accounted for and constitutes an error in the compu-
100177—24,——3
18 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
tation. The gain or loss of body protein and fat, computed from the nitrogen and carbon balances, and their equivalents in energy are given in Table 13.
TaBLeE 13.—Daily gain (+) or loss (—) of body protein, fat, and energy
Energy Cow No. Period | Protein | Fat Protein | Fat | Sum | | Grams | Grams | Calories | Calories | Calories I} 240! +37.7| —136.8] +358.2| +291.4 TS) LSA i i a cae SERRE a Ii] —36.0| +407.2| —205.2 |+3,868.4 | +3, 663.2 {WL | +115.8 |} +337.2 | +-660.1 |-+13, 203.4 | +3, 863.5 I} +204) 440.6) +116.3 | +385.7|) 502.0 (5 acl fp RE ede dues ok ai < II G12) 7126 | 41.0 | 119.7 |. —160.7 it IIL} 42.6) 42.9) —242.8) —407.5| —650.3 579 { I] +57.0} +6.3 | +324.9 |) +59.8 +384.7 anne an nnn nnn nnn anne nnn nana I} +108) +658! “+61-6 | }
+625.1| +686.7
The factors used in the computation of the nitrogen and carbon balances, as found in Table 11, to the corresponding amounts of protein, fat, and energy, recorded in Table 12, are the following: Grams of nitrogen multiplied by 6 equals body protein. The average per cent of carbon accepted for protein is 52.54 per cent: hence the number of grams of protein was multiplied by 0.5254 to get the number of grams of carbon in the protein. To compute carbon to fat the number of grams of carbon was multiplied by the factor 1.31, which corresponds practically to an average of 76.5 per cent of carbon in animal fat. The energy equivalents for protein and fat were con- sidered to be 5.7 and 9.5 Calories per gram, respectively.
COMPUTATION OF METABOLIZABLE ENERGY
The milk of the cow may be considered in the same light as body gain, in which case the energy of the excreta must be corrected for the potential energy of the milk protein. On the other hand it may be considered as a product in a sense apart from the body which, being neither body gain nor an excretum, is not involved in the computation of metabolizable energy. Although a column setting forth the metabolizable energy according to the first view, that is, considering the milk as body gain, is given, considering it as a product entirely apart from body gain is assumed to be the correct view for this class of experiments.
In Table 14 are found the results obtained by using the following three methods of computation:
No. 1. Gross energy of the feed minus the chemical energy of feces, urine, brushings, and methane, the nitrogenous outgo being corrected to body nitrogen equilibrium, ignoring the milk.
No. 2. The same as No. 1 except that the heat oi fermentation is treated as an excretum.
No. 3. The same as No. 2 except that the milk is treated as body gain. ~ In Table 14 the values for the gross energy of the feed and of the feces are obtained from the digestibility tables in the appendix. The other values needed in the computation are recorded in preced- ing tables. A comparison of the metabolizable energy as deter- mined by the three methods of computation shows the amount metabolizable according to method 2 to be from 17.28 to 19.92 per
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS
19
cent less than according to method 1, and that the amount by method 3
is reduced by about 2 per cent additional.
Reckoned as per cent
of the digestible, however, the metabolizable energy, according to methods 2 and 38, will show higher figures than by method 1.
TABLE 14 (Part 1).—Data incident to computation of metabolizable energy
| Chemical energy Cow No. Period 7 | Heat of Feces | Urine Bask Methane} fermen- 8 tation | : | A B ; Calories Calories | Calories | Calories | Calories I}; 10,820.6 | 1,583.8 110.1 | 2,628.0] 3,455.6 OSG t. eBee egy) tye II |. 11,026.0 | 1,691.1 | 78.3 2, 522.5 | 3,316.9 III} 10,702.9} 1,431.8 93.7 | 2,419.5] 3,181.5 if I} 11,397.3 | 1,323.4 107.5 | 2,404.6 3. 161.8 Gliese re ee TE} 22, O76. 7 | 325.400: 37) 87.6 | 2,420.1 3, 182. 2 | ‘| TEE AD, Ades | 89.1 | 2,457.3 | 3,231.1 579 { I! 11,459.0 1, 487.2 70. 2 2,792.0 | 3,671.2 BYP ELIE R TES Bat eate? IL | 11, 655.5 | 1,611.3 | 87.7 | 2,835.2] 3,728.0 | Energy of excreta (corrected) Meta Gross Cow No. | Period | ehereyi0lii as ma pape ae ee | | feed | Method 1 | Method 2 Method 3 | Method 1 | all Ea | Calories | Calories | Calories | Calories Calories | I | 32,4626 15,1127] 18,568.3| 18,853.3| 17,349.9 ra v2t CLES tee 2 RES a II | 32,3640 | 15, 273.2 18, 590. 1 | 18, 640. 8 17, 090. 8 | Til 32, 191. 6 | 14, 791.7 17, 973. 2 17, 973. 2 17, 399. 9 | I 33 igs ges 15, 258. 1 18, 420. 2 18, (O21 18, 253. 2 G15! a tyne | II 33) 407.8 | 14, 975.7 18, 138. 0 18, 57. 1 18, 432. 1 | Iit Bap Sooee: | WpsO2o.1 18, 256. 2 18, 601.8 18, 307. 2 579 if I 36, 762.6 | 15, 879.2 e 550. 4 19, 916.9 20, 883. 4 Sei tains poe i II | 36,791.4 | 16, 203. 1 | 2 931.1 | 20, 299.0 | 20, 588.3
: TaBLe 15.—Comparison of two methods of computation
| Corrections to excre- | tory energy for | protein | | Body | gain or Milk loss | | | Calories | Calories | —29.8 +285. 0 ee a +50. 7 +143.8 |} (Dry) |} +25.3 +331. 9 —8.9 +360. 1 | 50. 95) 2 een +70. 8 +366. 5 +13.4 +367. 9 bolizable energy Method 2| Method 3 Calories Calories 13, 894. 3 13, 609. 3 13, 773.9 ES, (Zee 14, 218. 4 14, 218. 4 15, 091.1 14, 759. 2 15, 269. 8 14, 890. 7 15, 076. 1 14, 730. 5 lity 24222 16, 845. 7
16, 860.3 | 16,492. 4
of metabolizable energy
Cow No. 73 ek Bee ae Se a Average Les See ae oe Ra ee ye ee ee es ih; See Babe SS cau ren iee Average
|
|
| Usual method | Improved method | | : : Pendent Totalenergy | Digesti- Totalenergy | Digesti- ble ble | | energy | | energy | Digesti- Metabo-| metabo- | Digesti: | Metabo- | metabo- | ble lizable | lizable! ble 2 lizable 3 | pees 4 | Percent | Percent | Per cent | Per cent | Percent | Per cent f I 66. 67 53. 44 80. 16 | 47. 92 42. 80 | 89. 31 mel IL | 65. 93 52. 81 80. 10 | 47. 89 | 42. 56 | 88. 87 i Ill 66. 75 54. 05 80. 97 | 49. 35 44.17 89. 50 | 66. 45 53.43 | 80.41| 48.39| 43.18 | 89. 23 | I} 65.99}; 5447| 8254| 49.38] 45.03| 91.19 aes GR 66. 84 55.15 | 82. 51 | 50. 07 45. 62 | 91.11 | III 66. 62 54. 92 82. 44 | 49. 56 | 45. 23 91. 26 | 66.48) 5485| 82.50) 49.67| 45.29] 91.19 | I} 68.83) 56.80) 8252] 51.25| 46.82 91. 36 ati tT | i | 68. 32 55. 96 81. 91 50. 48 45. 83 90. 79 68.58; 56.38; 8222| 50.86| 46.33 91. 08
1 From ‘‘ Metabolizable energy,’’ method-1, Table 14, and ‘‘ Digested Calories,’’ method 1, Table 9. 2 From Table 9, method 3. 3 From ‘‘ Metabolizable energy,’’ method 2, Table 14, and ‘‘ Gross energy of feed,’’ Table 14.
4 From ‘‘ Metabolizable energy,’’ method 2, Table 14, and ‘‘ Digested Calories,’’ method 3, Table 9.
20 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
Since the energy of the digestible nutrients is determined by sub- tracting from the gross energy of the feed the energy of the unused residue from the same, then all factors whatsoever of unused residuum should be consistently accounted for in this computation and that of metabolizable energy as well; and, in view of the fact that this is a departure from the customary usage, the usual method—based upon
feed constituents minus feces constituents—as well as the improved method—considering also other excreta—has been used. That the ©
heat of fermentation does not belong either to the digestible or to the metabolizable portion seems clear, the only question being as to the accuracy of the basis for its estimation. ~
The metabolizable energy computed as per cent of the digestible (method 1, compare with the usual, and method 2 with the improved conception of digestibility) are reported in Table 15. This table shows a close agreement from period to period, and also among the
different animals. HEAT EMISSION
The heat given off by the animal while in the respiration calo- rimeter is removed from the apparatus in a current of water, in water vapor, in excreta, and in milk, and the sum of the heat thus removed corrected for the introduction of feed and water as well as for the man engaged in milking, is the total heat emission. Under the heading “radiation,” etc., in Table 16 is included all the heat except that removed as latent heat of water vapor, and in the last column the heat by radiation is expressed in per cent of the total. This heat emission, however, is not necessarily identical with the total heat production of the ration fed, but must be corrected for change in live weight of the animal and for any change in the body temperature. This correction has the effect of rendering the data representative of the body in such condition as at the beginning of the experiment.
TABLE 16.—Heat emission per day and animal
alas Latent | By radi- | | Radiation aie
= x | pie heat of Total | ation, etc., Cow No. | Period | pacer water heat | in per cent
vapor of total
Calories Calories Calories Per cent { I 7, 359. 6 4, 487.6 11, 847. 2 62, 12 SOULS see Rats Ss eB oe ee s II OU, 2 4,451.6 12, 201. 8 | 63. 52 i. ee 9, 265. 4 4, 164 13, 430. 1 68. 99 1 7, 843.3 3, 870.8 11, 714.1 | 66. 96 UG ee 5 Se es hres ae ee NIE Sa II §, 619. 2 3,577.9]. 12,197. 1 70. 66 Ill 8, 871.8 3, 019.2 |} 12,391.0 71. 60 579 if Ji G, 450.8 4, 204.5 13, 655. 3 | 69. 21 igi ona creat amin Sila Susie + Satan a naa i\ II 9, 386. 5 3, 861. 7 13, 248. 2 70, 85
INFLUENCE OF BODY TEMPERATURE
The temperature of the body of the animals was taken daily at the rectum, by means of the usual clinical thermometer. During the feeding in the barn this temperature was always taken at the same hour, but during the calorimeter experiment could not be taken at the same hour of the day as at the end without destroying the equi- librium of the apparatus. Also at this time it had not been learned that the thermometer must be inserted to a depth of at least 6
inches in order to obtain correct readings, as Kriss (6) has subse-
—_——
ua tee,
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 21
uently shown to be necessary. Further, the writers are not sure that the rather sudden temperature changes recorded indicate cor- rectly the temperature changes of the whole body. In view of these uncertainties the small variations, a few tenths of 1 degree Fahren- heit, while in the calorimeter are of doubtful significance; and, there- fore, in this experiment no corrections have been made for these apparent changes in body temperature.
CHANGES IN LIVE WEIGHT DURING THE CALORIMETER EXPERIMENT
Between the time of entering and leaving the respiration calo- rimeter there is frequently a considerable change in the live weight of the animal. This change is due especially to variation in the amount of water consumed; also, to an important extent, to irregu- larity in the voiding of excreta; and, further, to actual gain or loss of body substance.
TABLE 17.—Changes in live weight of the cow while in the calorimeter
Period I Period II Period III
Gain | Loss Gain | Loss Gain | Loss Cow 631: Grams | Grams Grams Grams Grams Grams ALO ee 2258 Roce eee eh de Pk bee | ASE894. 2s brb8oud: |=. 5+ = 2 ee | 10, 536.2 Dry matter irregularity— He SAEs AE RIA ERAN Bie OF EA A ETD 66. OF LAR 2 9 he TER 8 ee 2 Doe WE XCTOUS § oo = 22 Se ee] Cy i 1, 33255) [hoo got = 614.14 do ESET TIL RN En al lees gn a aN PNR gy he adc 36.0 fis see es pgs een, Pees Dees SV Ay A eee AQ? 23 | 325 Sateen) eee Balan Coe ttre a as Nad hg ee ge ei: Nal ee ia a iE ete oA ay 5 9 A 9,469.1 ie Sos 18, 984.2 | 18,984.2 | 7,325.4 | 7,325.4 10, 586.2 | 10, 536.2 Cow 615: | | Wraten-ce cel type ee ee ee ee eh eh ee ae AS 85128) 12 9 F-. - SOO) Blea eee ee 17, 546.5 Dry matter irregularity— [it oes Se goat i SVE TS Os 0 oe eee ae eee Pe igs eee BS. Sa peers lp Pe ey4aa5 decteetse ee 31.7 HEXCT OPA Ee ee ee ee YE we hy [hee here CSOT eee G17. S4. S Toten ee ek Sree 2 A” See A a SWE 72D | eee 42.6 icity Ae ee ee 2) ROE 4! Se Tee FY ia |e Se See ere PA at ee | 42.9 Balarice te26— beit AS ei eee. 2 dw 42.9902, | 22 — Sans 22378. Seles 17,045: 9) eee 13, 855.3 | 13,855.3 | 3,314.8 | 3,314.8 | 17,663.7 | 17, 663.7 Cow 579: NUP ely Aeeetcd ena. Ee MER Cora REE o ed gee (ieee ZONED? Oe ork woe eb) 7, O86) 4 ee aa ee Dry matter irregularity— : Sree Hae tL exepiseay es SOR ON 63.5 4s oe ee ee Wim crcieeee rents eel. Ere TREO es PE be 2 8 Ay at Pepa | Es ee TOUCH fe oe eee ete LEER ee EMO eee eee 1058 (22 ee en a ina ee ne Posi Dee es seca 6528. [28520 SE ed eee 2 EAPUGSG (72a eR tie ET ao ee ee i EO-OG1e GUS sve ore 163417 ie oe Se a eee
Ec Saal bre ae eet caer ee ee = | 20, 772.9 20; 772.9: | 12, 086-4 |17;086.4,).- 22.22 | epee ==
| i
As already explained, during the calorimeter period the animal is assumed to have the same body temperature at the beginning and at the end of the experiment, so that no correction was made for change of temperature; but a heat correction is necessary for the change in live weight. Hence the character and quantity of this change must be determined, and a balance of the live weight of the animal has therefore been computed, which shows the total daily change in live weight due to various irregularities of excretion, etc., and the gain or loss of body tissue while the animal was in the calo- rimeter. The various items which enter into such a computation and the balances are given in Table 17. For the daily gain or loss of body protein and fat, the average figures as determined for the whole experimental period have been used, but the water is the
22 BULLETIN 1281, U..S. DEPARTMENT OF AGRICULTURE
actual water balance from the calorimeter period. The dry matter representing irregularity in the excreta and production of milk is the difference between the daily average for the experimental period and the amount produced during the calorimeter period.
The daily balances for the different periods and animals show a great variation, ranging from +7.2 kilograms to —19.1 kilograms change in live weight. This clearly demonstrates the unreliability of live weight as a measure in exact experiments, and the necessity, — in work in which live weights must be used, of basing conclusions on an average of several successive daily weights. A single weighing may happen to be correct, but, on the other hand, according to the above figures, it may be decidedly wrong, especially when intended to measure the gain or loss of body tissue.
HEAT PRODUCTION
To correct the heat emission for the change in live weight, in computing the heat production at a constant weight, the following factors for specific heat have been used: Water equals 1, dry matter equals 0.4, body protein and fat equals 0.3 and 0.66, respectively, the last two being estimated values as used by Armsby and Fries. The heat correction for the body gain or loss in live weight as thus computed is found in Table 18, which also gives the daily heat production.
The corrections for change in live weight are considerable, ranging as they do from +132.1 to —419.7 Calories.
COMPUTED HEAT PRODUCTION
For various reasons it is desirable to compute the heat production of an animal (indirect calorimetry) from the results of the gas and dry-matter analyses. Making this computation for a milking cow, under varying conditions, is a new people and one which requires discussion.
TABLE 18.—Correction for change in live weight, and daily heat production
Body loss (—) or gain (+) Daily heat Irregular ay j empera- - Cow No. | Period excretion i viareidi@ een . of dry | ference | 42 | Emission | FTOdUC- Water Protein Fat matter (corrected) tion (cor- rected) Grams Grams Grams Grams SC; Calories | Calories Calories — 166.0 I —18, 894. 2 —24.0 +37. 7 +. 1578.6 20. 53 —383.3 11, 847.2 11, 463. 9 631 Il +5, 585. 7 —36.0 +407. 2 +1 eat 5 20. 79 +132. 1 12, 201.8 12, 333.9 III |—10, 536. 2 +115. 8 -+-337. 2 +614. 1 21. 02 —210.9 13, 480. 1 13, 219. 2 —3.5 I |-13, 851.8 | +20.4| +40.6 { were \ 20.68 | —278.6| 11,714.1 | 11,435.5 é Th NS —44, 5 y 615 II | —3, 250. 5 (fer? 12.6 4941.0 \ 20. 59 59. 8 12, 197.1 12, 1387.3 —31.7 III |—17, 546.5 —42.6 —42.9 +617.8 20. 68 —358. 8 12, 391.0 12, 032. 2 | 1 |—20,772.9 | - +57.0 46.3 Heian 20.52 | —419.7 | 13, 655.3 | 13, 235.6 579 a II |—17, 086. 4 +10. 8 +65. 8 { ave 8 20. 99 | —352.0 13, 248. 2 12, 896. 2 ; | 1 Milk. 2 Excreta.
A milking cow may be maintaining her body tissue; she may lose or gain both body protein and fat, or she may lose one and gain the other. These different conditions of body loss or gain require appropriately differing consideration.
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 23
Thus, for example, starting with the assumption that the energy
of the feed minus the energy of the excreta equals the metabolizable energy then with an animal in nutritive equilibrium the total heat production (Table 19) equals the metabolizable energy. In case the animal gains body tissue the energy of the excreta is thereby lowered, the metabolizable energy is greater than the total heat production, and in computing the heat production, a correction for the chemical energy of the body gain must be subtracted from the metabolizable. Should the animal lose body tissue, then the heat production and the energy of the excreta are thereby increased by the energy equivalent of the tissue lost, and in computing the heat production the chemical energy of the body loss must be added to the metabolizable. ' It may be assumed that in the case of a cow receiving sufficient energy in her feed for maintenance, and also to supply the greater portion of the energy of the milk, any loss of body tissue goes to support the milk production, and that therefore the energy of this loss has been transferred to the milk. This transformation of body tissue into milk involves but a small loss of energy. Since the amount of this loss is not known to the writers, it has been omitted in the computation. Desiring at this time only to compare the total heat production as measured with the computed heat production, the heat of fermentation has also been ignored.
The computed heat production per day and head has been calcu- lated in accordance with the foregoing methods and the results given in Table 19.
TABLE 19.—Computed heat production (indirect calorimetry)
Period I Period II Period III Intake Outgo Intake Outgo Intake Outgo Cow 631: Calories Calories Calories Calories Calories Calories Heedaecs tt nb ern Me ae R2PABZHG Meee Ss ete 32,3040) eens eae S251 91 Gnl ees ree ee Mpces ue eet iil ee Re oe OPS20 Gy mente mem aa: 1026.01, | beni naam 10, 702. 9 Urine (uncorrected) ---__--|----_------- LOSo TO Seen aan GOT ee ce Be use 1, 431.7 IVES EN amie ree ch een [eee aye ZOO AON eens eee DOLLA OT tee. See 2, 419. 5 IBrushingssees ces ae ieee Sees NOE OU See ee eee sway Ree en eT ees 93. 7 WMilkanee ie ess) SUE io bdliee aha ELS Ds Ocean | ets ue tee TEEPE OREN ia VA eee ae Body protein______.------- Lo ite el Pee eee 205 52) | eas et ee eee 660. 1 IB Odwalabenr arte eine ef ye oe akites 7-15] (bin Se en S808 4. Ise ee 3, 203. 4 Balance seeker ee Sk alae MN oh ey oe DY eNO ee Seek ae 125985 Si eee eee 13, 680. 3 ot ale ee tits Sip Sika 32, 599. 4 32, 599. 4 32, 569. 2 32, 569. 2 32, 191. 6 32, 191.6 Cow 615: WCU se ee es ota oe AL ee SOP OUI Sy Peep ee SoH AO TSN fae ees SOOO L aos eee WCCESE eet eek eh ine cen ssi AE CES MSO FeO os a LIN OTGsi, bose ee 1253 Wirine (uncorrected) 2S 262|4.2 2.50. USA fd oes a Sie oe L409 2) Sas ace eee s 1, 406. 3 Methane siete Ae ey peek a ZPAOE Ore ee ZeAD lial eer eee ons 2, 457.3 IBEUSHIN PSone LOND ome = we O756. hobs umes 89. 1 NU ete paeeney te ire re OMe a Lk G8 O20 500 eee tala ate es GR 2(8o i eee ee eee 6, 157.0 BOG Ve DIOL nes = Soa ss ey ae See ek 116.3 Aly (QO) joxePSe Se oe 0 242) Bil ie Soe ee BoOdyriat=eset ss. Wee. eo 5 | actoeoes ui oe Ee 385. 7 51 A A (a pl ae ca 807.5) |eoeere eee Balan Cease ramen tts SS Ace Thi L565 5s ngs WDE I8642) (eo ee eee 12, 747.6 HE OUaeete Mee Lae wine ded 33, 511.3 33, 511.3 33, 568. 5 33, 568. 5 33, 982. 6 33, 982. 6 Cow 579 Headmasters Saye ool SONMLOZ. OF eee eee es LARIAT Uae: Sa ace aD Mall epee UT fea EE ol HGCES a teat Ny PECe Mey teers tee T4595 Ob pes os Sea ae Lh 65605) ) 2. 5 eae Sel eee 2 peed Urine (uncorrected) _._____].-_-___-__-- WEA Dil a Me er L612 3) ee e.6 5s ee ee Wiehhanelscreb AIEEC2 ole we go 332 iki 2hTOZ Oe: eee oe PPR fy Al Pe eee oe ARE LOGS SBS THSWINES 223 o yee 5 Cee OVS AO |e oh a LE Ba Ge a oe tk te OU a eee VEN Kerth eee ee ef we TH OZSO Eee arene ae Ge GAGs St eee Te ae Body protein e220 tse B2AO) luvs te tay ee. as GING ipee. ole oe SOGCVALAU SAS shee hee ne woe ee a OO es ape nile 62bur ce 2 Sue She ee eee Walance (setts ly eee eee TS 5453 9) SLL 2 As Yael 015) fi sigs! bee eas OD aS A Ae MOUs eee WL 36, 762. 6 36, 762. 6 36, 791. 4 36, 791. 4 |------------]------------
24 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
_ The heat production as computed and as measured by the respira- tion calorimeter is arranged for comparison in Table 20. The com- puted is also expressed in per cent of the observed.
THE OBSERVED AND COMPUTED HEAT PRODUCTION
The fairly close agreement between the computed and the observed heat production may be taken as a measure of the degree of accuracy to be expected from experiments on milk cows in a respiration chamber, using a bomb calorimeter for determining the energy of feed and excreta. :
In period III, cow 631, the heat measurement was adversely affected by the presence of an excess of air in the absorber water, and hence the heat for certain periods of time could not be measured. From the other main portion of the day the total heat for the 24 hours was computed by applying to the missing smaller sections the average heat per minute, as observed during standing and lying. This, of course, increases the possibility of error. However, the comparison with the computed heat production proves it to have been very small.
It will be noted that the computed heat production is, in seven cases out of eight, not more than 3.5 per cent greater than the ob- served heat production. In the nature of the case, this difference covers a considerable number and diversity of errors, all presumably slight. It appears that the true value lies above the observed, and that the computed values are therefore less in excess of the actual than is suggested by a statement of the computed as per cent of the observed. In the opinion of the writers the determination of heat production by indirect calorimetry is sufficiently accurate for pur- poses of research in the feeding of farm animals.
TABLE 20.—Observed and computed heat production
Heat production Computed
. ad in per Cow No. Period eantink Observed | Computed} observed Calories Calories Per cent u 11, 463. 9 11, 720. 5 102. 24 GS Re RPE AS le ee ee ee eS ee eS II 12, 333.9 12, 598.8 102. 15 Ill 13, 219. 2 13, 680.3 103. 49 I 11, 435. 5 1 756.5 102. 80 (Ls ES SS NU So Ss ES rN MO SSIES Wm 9 1) 0) ene, MR RE 2) | Il 12, 137.3 12, 286. 2 101. 23 Ill 12, 032. 2 12, 747.6 105, 95 579 { I 13, 235. 6 13, 545.9 102. 34 pieeeger eT cit GS Ca TS Tk DATES Le II 12, 896. 2 13, 165. 5 102. 09
NET ENERGY OF FEED FOR BODY GAIN AND MILK PRODUCTION
Before taking up the question of standing and lying it is desirable to determine the percentage utilization of the available metabolizable energy for body gain and also for milk production, using the computed heat values.* Cow 631 offers an excellent opportunity for such a comparative study. She was in full milk during one period, was almost dry in the second, and fully dry in the third period, whereas the ration remained the same throughout all the periods. This animal was standing during less time than she was lying, but the
4 In the following computations the data for the observed heat production have not been used, but are reserved pending the solution of a problem as to method of use.
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 25
ratio of time standing to time lying was about the same during each of the three periods.
THE MAINTENANCE REQUIREMENT
On account of unavoidable circumstances, it was impossible to determine the maintenance requirements of the experimental subjects. It was necessary, therefore, to assume these requirements on the basis of published averages. Lately Hills (7), from his extensive long-time practical maintenance experiments, reached the conclusion that Armsby’s and Kckles’s standards for maintenance of cattle per 1,000 pounds live weight are essentially correct. The maintenance requirements of the three cows therefore have been computed according to Armsby’s standard; they are based upon the live weight of each period for cow 631, and on the average live weight for cows 615 and 579. The results thus computed expressed in weight of dry matter of the feed, and its equivalent in metabolizable energy computed according to both the usual and improved methods, are given in Table 21.
TABLE 21.—Computed maintenance requirements of the subjects of the experiment
reported Metabolizable Feed dry eae energy Average | Digesti- Net SU ROS by Cow No. Period live ble true energy weight | protein Grain | Alfalfa | Usual | _2™
; proved mixture hay method | method
Kilograms| Grams Therms | Grams Grams Calories | Calories
I 334 185 4. 88 2, 132 1,445 } 8, 609.9 6, 895. 1
Gol == Se AE, aie II 360 195 5. 13 2, 236 1,523 | 8,935.2 7, 201.1 iil 390 205 5.40]. 2,364 1,600 | 9, 644.3 7, 880.9
I 196 5. 17 2, 259 1,532 | 9, 299.5 7, 688. 6
LOS Se ctw ayer II 366 196 5.17 2, 259 1,532 | 9,410.5 7, 785. 1 Til 196 5.17 2, 259 1,532 | 9,373.5 Gon
579 { I \ 370 { 198 5. 22 2, 282 1,545 | 9,785.8 8, 065. 5 BED te hg ean ae II 198 5. 22 2, 282 1,545 | 9, 524.8 7, 800. 1
In order that the continuity of the computations may be main- tained Table 22 has been inserted to show the influence of the cor- rection for body gain or loss on the availability of the metabolizable energy for milk production.
TABLE 22.—Influence of correction for gain or loss by the body on availability of the metabolizable energy for milk production
Energy correction for Energy available for body gain milk production Cow No. Period Usual Improved Usual Improved
method method method method
Calories Calories Calories Calories I +444, 4 +363. 2 8, 295. 6 6, 636. 0 "ERAS ey NS =a eu +7, 353.6 | +6, 009.1 802. 0 563. 7 Taba ScrulesS coa dh all Se a hall eke La 9k ne I | +1, 007. 7 +823. 5 7, 946. 0 6, 579. 3 PONG ERE Sip Rs AST T ALE NED ee ea yet dat II —160. 7 —160. 7 9: 173: 3 7,616. 5 Iil — 650. 3 —650. 3 9, 584. 0 8, 007. 3 579 I +772. 3 +631. 1 10, 325. 3 8, 515. 6 Masse weet re Eras GATE ATTIGe F II |} +1,378.5 | +1, 126.5 9, 685. 0 7, 933. 7
26 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
METABOLIZABLE ENERGY AVAILABLE FOR PRODUCTION
If the metabolizable energy of the feed required for maintenance is subtracted from the total metabolizable energy in the feed, the amount available for production is obtained. These values as well as those of the actual milk production and the body gain in calories are recorded in Table 23.
Having the above data the computation of the percentage utiliza- - -
tion and the net energy of the feed for the different types of produc- tion can be made.
TABLE 23.—Metabolizable energy available for milk production and body gain
Available for pro- Actual production
duction Cow No. Period Usual Improved NTs eae method method Milk Body gain
Calories Calories Calories Calories I 8, 740. 0 6, 999. 2 5, 378. 2 +221. 4 GOI IS racer ok Ea BAe sul ge fev he aa BN II 8, 155. 6 6, 572. 8 784. 1 +3, 663. 2 III Up aE GEOR YA hd pee ee ee +3, 863. 5 if 8, 953. 7 7, 402.8 6, 020. 0 +502. 0 GUD RP RS. oe ee a ee 8 Il 9, 012. 6 7, 455. 8 6, 278. 7 —160. 7 Til 8, 933. 7 Useeri 6, 157. 0 — 650. 3 579 { I 11, 097. 6 9, 146. 7 7, 023. 6 +384. 7 ean as es ee eae Sar cl II 11, 063. 5 9, 060. 2 6, 749. 5 +686. 7
NET ENERGY FOR BODY INCREASE
In period III cow 631 was dry, and gained body substance equiva- lent to 3,863.5 Calories. If this amount of gain is divided by the amount of available metabolizable energy, according to the two methods of computing it, the following results are obtained:
see =49.815 per cent utilization (usual method). aera 60.961 per cent utilization (improved method).
Since the body gain expressed in calories (assuming that there is no milk production) represents the net energy of the difference between the total feed eaten and the amount needed for maintenance, the net energy for body production per kilogram dry matter of feed mixture is obtained by dividing the calories of body gain by the difference between gross intake of feed and the maintenance require- ment.
Thus: 7,151.0—3,963.6=3,187.4 grams of feed mixture; and 3,863.5 Calories
(body gain) +3.1874 kilograms (gross intake minus the maintenance requirement) =1.2121 Therms net energy per kilogram dry matter of feed for body increase.
NET ENERGY FOR MILK PRODUCTION
Turning now to period I, the milk production of cow 631 was equivalent to 5,378.2 Calories, and at the same time the body gain was equivalent to 221.4 Calories.
The utilization of the metabolizable energy available for production was 49.815 per cent according to the usual method, or 60.961 per cent according to the improved method of computation. Using these percentages a correction for the 221.4 Calories gain by the body is obtained. Therefore, 221.4+0.4982 =444.4 Calories, and 221.4+ 0.6096 =363.2 Calories, respectively. Deducting these values from
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS AS
the two sets of metabolizable calories available, the total meta- bolizable energy available for milk production is obtained.
8,740.0 usual method. 6,999.2 improved method. 444.4 363.2
Difference, 8,295.6 Calories. 6,636.0 Calories.
These two values represent the amount of metabolizable energy available for milk production. Dividing the milk yield by these values the following figures are obtained:
5,378.2 X 100 8295.6 or 5,378.2 X 100 6636.0 To obtain the net energy value of the feed for milk production it is necessary first to correct the maintenance requirement so as to include the body gain and then subtract this amount from the total feed eaten. Thus, in period I, cow 631, the maintenance requirement including the body gain will be, using the old method, according to the proportion; maintenance metabolizable: maintenance metaboliza- ble + 221.4+49.815 :: weight of maintenance ration: X. .X =dry matter of feed. Thus 8,609.9 : 9054.38 :: 3577: X. X=3,761.8 grams of feed. as ration 7,208.4—3,761.8=3,446.6 grams of feed mixture for production of MILK, Dividing the milk calories by this amount the net energy of the feed for milk production per kilogram dry matter of the feed is obtained.
Thus 5378.2+3.4466= 1.5604 therms of net energy for milk production.
=64.832 per cent utilization (usual method),
=81.046 per cent utilization (improved method).
Hor ibGdyimercases 24 Ob) Us bel AS 1.2121 Therms of net energy. Hor milks production. 26... 7s 22 6 Bid 1.5604 TIER RRO peer ee aes Bier Be ap a ae 0.3483 = 22.32 per cent.
In this connection it is of interest to note that Hansson (8) from a very large number of long-time practical group experiments with milking cows has obtained for the individual grain barley, which is the standard for the feed-unit system, a net energy value for body increase equal to 1.650 Therms per kilogram of grain containing 14.5 per cent moisture, and for milk production a net energy value of 2.100 Therms, a difference of 21.5 per cent.
This shows a remarkably close agreement for the percentage difference between net energy for body increase and net energy for milk production, as found by different experimenters, especially when the extremely different methods of experimentation by means of which the results were obtained are considered.
It must be borne in mind, however, that in these experiments the maintenance requirement was computed from published averages and not determined for the cow referred to above.
Having thus determined the net energy value of the feed for body gain from the dry period of the one cow, by applying this value to the other cows, the percentage utilization of the metabolizable energy available for milk production may be computed in the manner
reviously described. The results of such computations are recorded in Table 24.
28 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
It will be noted in connection with the data presented in Table 24 that in summarizing the results of these experiments the net energy values given for milk production are based upon the results obtained with cow 631.
It is not impossible, therefore, that the proximity of parturition in the latter period contributed a confusing influence in the computation of the net energy value for body increase. Judgment as to this — possibility must await further evidence.
Since such a material difference has been found to exist between the two kinds of production values, it is desired for the present to call attention to them by using the terms, ‘“‘ Net energy value of feed for body. gain” and “‘ Net energy value of feed for milk production.”
TABLE 24.—Percentage utilization of metabolizable energy available for milk pro- duction and the net energy value for milk production
Utilization for milk production antckaal f nterv: Cow No. Pea) eta nuTES between | Usual | Improved periods method method Per cent Per cent Therms Days 631 I 64. 83 81. 05 1. 560 56 = ST aS aa Ea eS eee st Il 97.76 139. 10 2. 322 42 III Dry Dry 75. 76 91. 51 1.776 615_ --.---.---------------------------------- II 68. 44 82. 43 1. 699 \ 42 Ill 64. 24 76. 89 1. 589 LF 71) see eee GP BES Ee eee AS Sines See ee 28 SSE I} 68. 02 82. 48 1. 739 42 II 69. 69 85. 08 1. (au
Such distinction is in keeping with what Armsby has said on the subject of milk production, and with the practice of some present- day Scandinavian investigators.
These large differences in the percentage utilization of the available metabolizable energy and the net energy of the feed for milk and for body gain are evidence suggesting that, when an animal has suffi- cient feed, the dry matter of the feed does not first become body tis- sue and later milk. It is a process more direct and less expensive.
“DRYING-UP” PERIOD
In the computations to obtain the percentage utilization of the available metabolizable energy the results derived from experiments with the respiration calorimeter were applied, in each case, to the average milk and body gain for the digestion period.
It is not entirely satisfactory to study milk production in a cow which is giving less than 1 kilogram of milk in 24 hours. In period II, cow 631 though giving only 0.8 kilogram of milk per day was treated as in the other milking periods and is included in the above table. This period, however, requires a special consideration and discussion. During the drying-up period, which is represented by the data for cow 631, the percentage of daily decrease in milk pro- duction was considerable; and, since the calorimeter work was done at the beginning instead of the middle of the period, it is not a true representation of the average production during this rapid and con- tinuous decrease. If the results obtained with the respiration calori- meter are applied to the milk yield of the same day, and the body gain corrected in proportion to the milk yield and the body gain of
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 29
periods I and III, the following recomputation will give utilization and net energy values for this period which are probably more nearly correct.
The milk on the calorimeter day was 1.19 kilogram = 1,147.9 Calo- ries, a difference of 363.8 Calories from the average. This difference in milk production, based on period I, would be 363.8 + 0.6483 = 561.2 Calories (usual method) or 363.8 +0.8105=448.9 Calories (improved method) of available metabolizable energy.
But these values represent the reduction in body gain which, based on the percentages obtained in period III, would be by the usual method equal to 561.2 x 0.49815= 279.6 Calories of body gain.
In period II the gain was 3,663.2 Calories, and 3,663.2—279.6= 3,383.6 Calories corrected gain. Applying the percentage utiliza- tion previously computed we have 3,383.6 +0.49815= 6,792.3 Calo- ries (usual method), or 3,383.6 +0.60961=5,550.4 Calories (im- iat method) of available metabolizable energy which, deducted rom the total available, leaves for milk production the following:
8, 155. 6 6, 572. 8 6, 792. 3 5, 550. 4
1, 363. 3 Calories. 1, 022. 4 Calories. The corresponding percentage utilization would then be:
1, 147. 9X 100 1, 363.3
1, 147. 9X 100 1, 022. 4
The net energy for milk production can be computed as follows:
8, 935. 2 : 8, 935. 2+6, 792.3: 3.759: X. X=6, 616. 4. 7, 190. 1—6, 616. 4=573. 7 grams dry matter and 1,147.9 Calories+-0. 5737=
2. 000 Therms net energy per kilogram feed.
All these results suggest that the computed maintenance ration, at least for cow 631, period III, was too low. It had been computed in consideration of the increase in live weight of the animal; but since this increase must have been due largely to the development of the fetus, it seems possible that the increased weight on this account would represent more protoplasmic activity than the same increase of body weight apart from the fetus, the maintenance requirement, therefore, being greater. This may be true not only for period III but also for period II. In the light of other results, and the above hypothesis, it would appear that the maintenance requirement as computed for period III is about 2 per cent too low. If an allowance of 2 per cent increase in maintenance for period III is made, and the new values for body gain determined, the percentage utilization of the available metabolizable energy for milk production, with cow 631, period II, would be, computing as before, 74.91 per cent, or 98.92 per cent utilization (usual and improved methods, respectively), and the net energy for milk production 1.78 Therms per kilogram of dry matter of the ration.
Thus it is seen that a change of 2 per cent in the values for main- tenance will make the values applying to cow 631, period II, cor- respond to the other milking periods. The data as to cow 631, period II, therefore, constitute in reality a fair proof of the accuracy of the experiment as a whole, and also an indication that the main- tenance requirement of an animal in the later stage of gestation may
= 84. 20 per cent utilization (usual method).
=112. 27 per cent utilization (improved method).
30 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE
be higher than the average for the same body weight if the animal 'were not pregnant. If this is the correct interpretation, then the period in question also indicates that the estimated heat of fer- mentation used in the*‘improved method” of computing the metab- olizable energy is not far from the correct value.
The above observations as to the increased maintenance require-
ment during pregnancy in the cow are readily understood in the
light of the finding by Magnus-Levy (9) of a steady increase of oxygen requirement throughout the course of pregnancy in woman, the conclusion of Murlin (1/0) that the extra metabolism of the pregnant female dog, as related to reproduction activity, is propor- tional to the weight of the puppies at birth, and the findings of Carpenter and Murlin (17), in astudy of metabolism in three pregnant women, that the difference in heat production per hour, before and after parturition, was very nearly the same as that of the newborn infant, and that the rate of metabolism of the infant was 2.6 times that of the mother, in terms of calories per kilogram of body weight.
EFFECT OF ADVANCE IN LACTATION
Eliminating cow 631, which was studied during only one period in which milk was produced in any considerable quantity, the effect of advance in lactation on utilization of the available energy for milk production with the other two cows can be studied (Table 22).
Cow 615, whose tests extended over a period of 94 days, offers the best opportunity for study. With this cow there was a decrease in the percentage utilization of the available energy for milk produc- tion in each period. With cow 579, which had been in milk about three months at the time of the first period, there was a slight increase in percentage utilization during the second period. Hence no definite conclusion can be drawn from this experiment so far as the effect of the advance of lactation on the percentage utilization of the avail- able metabolizable energy for milk production is concerned, and the accumulation of additional data must be awaited.
STANDING AND LYING
The results of nutrition investigations, in order to be comparable, must represent certain uniform experimental conditions, any variations from which must be taken into account in the application of the con- clusions. Thus it is customary to compute the experimental results obtained with animals of different weights so as to apply to animals of standard weights, usually either 1,000 pounds or 500 kilograms live weight. Also it is understood that feeding standards apply exactly only under conditions essentially the same as those under which they have been established, which in connection with this study means comfortable stable conditions and from which it follows that allowance should be made in the application of the conclusions and of all feeding standards for any considerable departure from the basic conditions implied.
Earlier experiments on steers with the respiration calorimeter established the fact that irrespective of the et, or quantity of feed eaten there is always a large percentage difference in the amount of heat given off by the animal according to its position in regard to standing and lying. Although the animal in the course of the day in these experiments always gave off more heat per minute while standing than while lying, as the data accumulated it was noticed
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 31
that results in different periods with different kinds or quantities of feed did not agree so closely as was to be expected in consideration of the time of standing and lying and the respective rates of heat emission.
This led Armsby to collect the available data and, after a careful study of the relation of change in quantity of feed and of variation in length of time spent standing and lying to increase in heat emission due to standing, to make the following statement (/2): “It is clear, therefore, that despite the apparent uniformity of experimental conditions the metabolism of the animals was affected by influences other than the feed or the proportion of time spent standing.” That is, the total observed difference in heat emission per minute between standing and lying can not be ascribed entirely to the muscular work due to standing.
The following are some of the outstanding experimental facts as to heat emission in relation to standing and lying:
The average heat emission per minute of standing is always much greater than that per minute of lying.
Body temperature does not change with change of position.
With an increasing ration there is usually an increment in the heat emission per 24 hours of standing. There is, however, a lack of uniformity in the results, and negative differences have also been observed.
With an increase in feed there is almost invariably an increase in methane fermentation, and a part of the heat of fermentation will be included in the increment of standing.
An increase of a few kilograms in live weight does not noticeably affect the heat emission during standing.
There is no strict quantitative relation between the heat emission per minute and the length of time spent standing.
Mollgaard (13), discussing the results of standing and lying, did not find the consumption of oxygen to vary with the time spent in these positions, and Pattever that there is in the end a compensation taking place within the animal of such nature that after a longer Heriod of standing, and therefore greater fatigue, the metabolism of the animal decreases on lying down to a greater extent than after a shorter period of standing. However, experiments of the writers cover many instances in which long periods of standing do not influence the heat emission during lying to a greater extent than do shorter periods; and Mellgaard’s hypothesis does not explain the irregularities in the oxygen consumption, or the processes involved in producing such differences in heat emission as have been noticed in the calorimeter experiments.
Observations on the heat emission during lying and standing, together with the fact that at certain periods of the day the oxygen consumption ‘ of the animal does not follow the carbon-dioxide pro- duction, would seem to indicate that conclusions can not be based on short sections of the experimental day since these are not reliably ples of the whole day or of the prevailing habit of life of the animal.
hat it requires energy for an animal to lie down and to get up, and muscular energy to support and balance the body in a standing position, is self-evident, but as to the exact quantity of energy thus used the evidence at hand does not warrant a definite conclusion.
* Unpublished data of the institute.
32 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE |
As in the steer experiments so also with the cows a large percentage difference in heat emission per minute of standing and lying was observed. But since Armsby himself felt that the earlier correction, relating the total difference in heat emission to potential energy of body substance, was unsatisfactory, and since at present the causes for the difference in heat emission between the standing and lying postures are not fully understood, it has been thought advisable not | to apply a correction for standing and lying in this experiment at this time. Subsequent experiments, not yet studied, may add sufficient light to clear up this problem.
The heat emission per minute of standing and lying has been computed from the heat as measured by the calorimeter, assuming the latent heat of water vapor to be in the same ratio as the heat of radiation and conduction for standing and lying. The heat pro- duction, as computed from heat emission by making a correction for the potential energy of gain or loss of body substance, is recorded in Table 25.
TABLE 25.—Heat production standing and lying
i
Observed heat ra- | : diation and con- | Latent 4,,,, | Total production | Time | Hest Toe Cow | Pe- duction | heat of craieiia ying = No. | riod | water | standin and | | | vapor | S@ 8 | standing ! Standing) Lying | ‘Standing | Lying | ‘Standing Lying
Calories | Calories Calories Percent Calories | Calories Minutes | Calories | Calories
I} 2,983.2 43764 | 4,487.6 40.535 | 4,646.9 ea “As 10.146 6. 942
631 |) II) 3,670.0 4, 080. 1 | 4,451.6 47.354 | 5,840.6 | 6,493.3 | SA 10.935} 7.168: lr | 4,132.2) 5,138.3] 4,164.7) 44597| 58054] 7am84 7) 4s) 7.920
I} 3,771.8) 40715] 3,870.8| 48089) 5,490.2) 5,9363{ 28) 9.224) 7.035
615} | 6,153.5 2,465.7| 3,577.9| 71.300 | 86648 | 347251 Set | 0.53! 6.551 Unt | 6,260.9 . 2,610.9| 3,519.2) 7o571 8,491.2) 354.04 for} 9465 6522 ms I} 7,2828 2168.0] 42045) 77.060, 10,1994] 3,036.2\{ go § } 10.255, 6.816 UT) 6,135.4, 3,251.1) 386.7) 65.364 8,420.5] 4407 4 Song |} 10412 7.085
1 The upper figure in this column should be read as minutes lying; the lower figure as minutes standing-
SUMMARY
The net energy of the feed for body increase and for milk production as determined for one cow was: For body increase, 1.212 Therms of net energy per kilogram of dry matter of feed; for milk production, 1.560 Therms not energy per kilogram of dry matter of feed—a difference of 22.32 per cent.
The percentage utilization of the metabolizable energy available for milk production ranged from 60.13 to 75.76 per cent according to the usual method, and 73.08 to 91.51 per cent according to the improved method of computing the metabolizable energy.
The difference in the net energy values of feeds for body increase and milk production indicates that milk production takes place, normally and principally, not by the transformation of body tissue but by a more direct and a less expensive process.
The computed heat production of milking cows is, on the average, between 2 and 3 per cent higher than the observed heat production
MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 33
as measured by the calorimeter. This difference indicates the degree of accuracy which may be expected from metabolism experiments where only the respiration chamber and the bomb calorimeter are employed, as compared with results from the use of the respiration calorimeter. The presumption is that the direct measurement of heat production is less than the actual, and that the error involved in the indirect measurement of heat is therefore somewhat less than suggested by the foregoing figures.
Indirectly. the results from one cow seem to indicate that in the last stages of gestation the animal requires approximately 2 per cent more feed for maintenance than an animal of the same weight with- out a developing fetus.
The apparent digestibility of the feed, in terms of energy, was the aaa for two of the cows, and for the third approximately 2 per cent higher.
The difference in the digestibility of the feed, in terms of energy, when computed according to the usual method, as compared with the improved method, which considers all useless matter and energy in the hight of excreta, was from 16.6 to 18.8 per cent.
The percentage difference in heat emission for standing and lying as determined with cows was similar to that obtained with steers in earlier experiments.
The dry matter of the feces, notwithstanding its much higher percentage of ash and lower percentage of ether extract, has a higher energy value per gram than the dry matter of the feed.
Methane production tended conspicuously toward uniformity, and the average per day for the eight periods was 191.8 grams, or 267.6 liters of CH,.
During the drying of the feces to the air-dry condition there is a loss of about 10 per cent of the total nitrogen; hence it is necessary to determine nitrogen in the fresh material.
LITERATURE CITED
U.S. Dept. of Agr., Office of Exp. Stas. Buls. Nos. 63 and 136. (2) U.S. Dept. of Agr., Bur. Anim. Indus. Report, 1906. Am. Soc. Anim. Prod., Rept. of Proceedings 1922, pp. 33-46. U.S. Dept. of Agr., Office of Exp. Stas. Bul. No. 136, pp. 146-148. (5) U.S. Dept. of Agr., Bur. Anim. Indus. Bul. 128, p. 1138. (6) Proc. National Academy of Sciences, vol. 6, pp. 539-541 (1920). (7) Vermont Agr. Exp. Sta. Bul. No. 226, p. 182. (8) Kungl. Landtbruksakademiens Handlingar och Tidskrift, 1923. (9) Zeitschrift fiir Geburtshilfe u. Gynakologie 52 (1904), 116. (10) Proc. Am. Physiol. Soc., Amer. Journ. Physiol. 23 (1909), p. xxx11. (11) Archives of Internal Medicine 7 (1911), p. 184. (12) Jour. Agr. Research, vol. 11, No. 6, p. 467. (13) 111'* Beretning for Forségslaboratoriet, Copenhagen, 1923.
APPENDIX
TaBLE I.—Apparent digestibility of ration—Cow 631
| |
Nitro- gen- free ex- tract
Crude fiber
| Grams | Grams
70. 80
351. 2 |2, 923.3 805.7 |1, 293.3
1,156.9 |4, 216.6 761.2 | 937.5
395. 7 |3, 279. 1 34.20) = 77.77
Or- Dry | - Pro- | matter | eee tein Period I Grams | Grams | Grams 371) eee ee Grain mixture_____- 4,290.2 4,098.4 | 598.4 Alfalfa hay___.___-- 2,918.2 2,680.1 | 429.4 | Total eaten_-|7, 218.4 |6,778.5 |1, 027.8 Reresees Bes dae! 314.8 (2,067.0 | 272.7 Digested _____ 4,903.6 |4,711.5 | 755.1 Coefficient of di- gestibility________ |} 67.93} 69.51! 73. 47 Period II Bale? 2h 10.0 Grain mixture____- 4, 247.1 |4,060.9 | 591.1 Alfalfa hay__‘_____- 2,943.0 |2,701.2| 414.1 Total eaten __|7, 200.1 |6, 762.1 /1, 005. 2 eCAS oes ke LS (2,390. 6 |2,123.9 | 269.5 Digested _____ ‘4,809. 5 |4, 638.2] 735.7 Coefficient of di- | gestibility_______- 66.80) 68.59} 73.19 Period III Salteetiyss fy ey sor 8 10.0 Grain mixture_____/4, 211.0 |4,027.0 | 579.9 Alfalfa hay________- '2, 962.3 |2,708.1 | 433.2 " Total feed of- | Ged Sse 7, 183. 3 |6, 735. 1 |1, 013. 1 Refused feed __-____| 3 20. 8 3. Feed eaten___ 7,161.0 /6, 714.3 |1,010. 1 12.27 ei 2, 326.1 |2,063.7 | 278.3 Digested _____ 4,834.9 [4,650.6 | 731.8 Coefficient of di- | gestibility________ | "6és52} (69:26he (72.45
34
20. 3 87.6
107.9 37.2
70. 7 65. 52
121.6 a)
121.1 24. 5
96. 6 79.77
350. 3 |2, 892. 0 808. 3 |1, 316.3
1, 158. 6 |4, 208.3 783.9 | 969.1
374. 7 |3, 239. 2 32. 34}; 76.97
1, 149. 2 |4, 177.9
4.0 12.5 1, 145. 2 |4, 165. 4 767.1 | 929.5
378. 1 |3, 235. 9 33.02) 77.69
Ether ex- tract
SS a a ES ee SS SS
5 76. 23
Total nitro- gen
105. 8 85. 4
191.2 49.6
67. 19
Grams | Calories
1, 979. 7 |19, 518. 1 1, 335. 0 |12, 944. 5
3, 314.7 |32, 462.6 1, 087. 4 |10, 820.6
2, 227.3 |21, 642.0 66. 67
21, 338. 0 65. 93
1, 355.8 |13, 154.2 3, 296. 7 |32, 291.8
10.2} 100.2 3, 286. 5 |32, 191.6 1, 079.8 |10, 702. 9 2, 206. 7 |21, 488.7
67.14} 66.75
MILK PRODUCIION AND BODY INCREASE OF DAIRY COWS
TABLE II.—Apparent digestibility of ration—Cow 615
35
| Nitro- Dry..| ganic | Pie | pro | Guide| gem | Nore” | nitro | 9" | nergy matter | matter tein tract | tract |’ gen Period I Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams | Calories SHEL Feces = Sok Dealt ce ORR er ee | rece penetra ee A hl oe oe Grain mixture______|/4, 447.8 |4, 249. 0 620. 3 17.8 364. 1 |3, 030. 7 208. 8 109. 6 |2, 052. 4 |20, 235. 0 Altalfathiy<s* sis 2, 993. 0 2, 748.8 | 440.4 80.8 | 826.3 |1, 326.5 74.9 87.6 |1, 369. 2 |13, 276.3 Total eaten__|7, 450. 8 |/6, 997.8 |1, 060.7 98.6 |1, 190.4 |4,357.2 | 283.7 | 197.2 |3,421.6 |33, 511.3 INGCES. Lor nee 2, 450. 3 |2, 204. 1 294. 2 24. 0 786.7 |1,039.1 | 60.2 52.2 (1515055 i 397. 3 Digested 5, 000. 5 |4, 793. 7 766. 5 74. 6 403. 7 |3, 318. 1 223. 5 145. 0 |2, 271.1 |22, 114.0 Coefficient of di- Pestibilitye.2-.-2- 67. 11 68. 50 72. 26 75. 66} 33.91 76. 15 78. 78 73. 53 66. 38 65. 99 Period II | Rel) Papp (oh Meee den poke CEST a [Sk A aa | a eae Maa erty (oa aie te ALS [Ne eden (ache beeece MP owe mem ae) ot ESE SC of Se Grain mixture______!4, 403.1 /4, 210.1 612.8 Peat 363. 2 |2, 998. 2 212. 7 109. 1 |2, 027.8 |20, 026.9 Alfalfa hay ete 2 3, 018. 4 |2, 770. 4 | 424.7 89.8 829. 0 |1, 350.0 76.9 87. 1 |1, 381. 2 |13, 380. 9 Total eaten__ Z 431.5 |6, 980.5 (1, 037.5 110.9 11, 192. 2 |4, 348. 2 289. 6 196. 2 |3, 409. 0 |33, 407.8 Weces.)- eens 2,385.1 [2,145.6 | 248.1 57.7 | 738. 1 |1, 035. 7 65. 9 52.0 |1, 120.3 |11, 076. 7 [AS a (28 Tone aa TAS hath e Digested ____- 5, 046.4 [4,834.9 | 789.4 53.2 | 454.1 |3,312.5 | 223.7} 144.2 |2, 288.7 |22 331.1 Coefficient of di- gestibility_-_.__- 67.90| 69.26 76.09] 47. 97| 38 09| 76.18} 77.24| 73.50} 67.14] 66. 84 __ Period III | | Gas meter pear ated CES ee een fate | ee ocean (ee Pee | (se See eye (gees Weal] AIRES IE Mae Gea mixture_____-_/4, 365.8 |4,175.0 | 601.2 28.5 | 349.6 |2,994.1 | 200.0! 108.7 /|2,012.3 /19, 841.1 Alfalfa hayes h Bp 038. 2 2, ieenO 444.3 96.5 832.8 |1, 323. 0 80.8 | 91.6 |1, 390.6 |13, 491.2 Total eaten__|7, 414.0 |6, 952.5 |1, 045.5 125. 0 |1, 182.4 |4, 317.1 280. 8 200. 3 |3, 402.9 (33, 332.3 Mecasece ete id. 2,404.3 |2,158.5 | 288.4 PRAY ETO aE 58.3 | 59.7 |1,125.1 Ee 1258S Digested ____- 5, 009. 7 |4, 794.0} 757.1] 102:7]| 367.3 |3,342.5 | 222.5 | 140.6 |2,277.8 |22, 207.0 Coefficient of di- gestibility_._____- 67. 57| ~ 68.95| 72.42) 82.16) 31. i 77.42} 79.24| 70.19] 66.94 66. 62 TABLE III.—Apparent digestibility of ration—Cow 579 Nitro- Dry ee Pro- ae Crude | _gen- = : eee Car Energy matter raiattae tein fon | fiber free eX-| tract gen bon ract : Period I Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams | Calories TU tS REE a Ae ae 1OFOuleee = = | en eee tetas Wd el AOE a ay Bl Llane ni ee Rs Bel heediriedecsinse |e fd 2 Grain mixture__-_-_-_- 4,820.6 |4,609.3 | 670.9 23.1 | 397.6 |3,282.5 | 232.8 | 119.4 |2,220.1 | 21,925.9 Alfalfa hays oe 3,346.8 (3,071.8 470.9 99.6 919.2 |1, 496.9 85.3 96.5 /|1, 531.5 | 14,836 7 a a SS SS } — Total eaten_-___! 8,177.4 |7, 681.1 {1,141.8 122.7 |1,316.8 |4; 779.4 318. 1 215.9 |3, 751.6 | 36,762.6 Feces] 2s sae: \2,481.8 2,211.8 | 281.1 42.5 | 815.3 |1,008.8 64.1 | 54.0 {1,154.0 | 11,459.0 Digested _____- '5, 695. 6 '5, 469.3 860. 7 80.2 | 501.5 |3,770.6 254. 0 161.9: |2, 597.6 | 25,303.6 Coefficient of i- | gestibility____.___- 69. 65 71. 20 75. 38 65.36; 38.08 78. 89 79.85) 74.99 69. 24 68. 83 Period II | | | BONES t Mera Yak > HOGG 1 eee bch mate A enateee Sela ny Sob op oh a Grain mixture______- 4,804.0 4,594.1 661.8 31.4 384.7 |3, 294.6 220.0 | 119.6 |2, 214.4 | 21,832.6 Alfalfa hay_-_._.---- 3,368.7 '3,079.6 492.7 107.0 923.4 |1, 466.9 89.6 101.6 1, 541.8 | 14,958.8 Total eaten __-|8, 182.7 |7, 673.7 I, 154. 5 138. 4 1, 308. 1 4,761.5 309. 6 221.2 3,756.2 | 36,791.4 MOCES = Has: a Fates s > le 283. 2 Sieg 837.1 |1, 031.5 62.6 56.3 1, 180.7 | 11,655.5 Digested ____-_- 5, 653. 7 |5, 407. 4 871.3 86.7 471.0 |3, 730.0 247.0 | 164.9 |2,575.5 | 25,135.9 Coefficient of di- | gestibility._._..-_- 69. an 70. 47 75. 47 62. 64 36. 01 78. 34 79. 78) 74. 55 68. 57 68. 32
36 BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE TaBLE [V.—Dry matter per day and the balance of water—Cow 631 Period I Period IL Period III Water! Wat Dry er De ater Dry Water matter tneome Outgo eines Income |} Outgo riperer | Income | Outgo Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams Alfalfa hay —..2--. 2, 918.2 74 (CL) ee eee 2, 943.0 Zt; Ole nee , 962.3 Pe bees || fr i Pe oe, Grain mixture_____- 4, 290.2 635: 0)2.4 3.2. 4, 247.1 6980/3 4,211.0 693. 0) Sears ered geeiiness 2) cide} ads ned cl See | Lee Ll ey Biss ee 15.2 = sd Cees pS ee LTP (] ea aameletel 12 TE Ss sal aR O Ss yeas eee 110,355: 6) ne CCCS er fy tis Be ae 2, 314. 2, 390. 6) 2, 326. 1) ATT ee eC ae 586.0 {77-77-77 14, 268. of Seal -+------ 9, 821.0)) “539, ait -------- 14, 337.4 Hair and brushings. 7 as ee ee 1.9 1 boar f | Seapaee ele 0.9 ap dag 5 Ps by = 1.4 SS = eet ee a O00 Fi S2ck eed 2554353 5 TE es ae O76}, Nene: |. o2 ee Correction for COsz: | ier 44 bes —14.2 7S) epee mo ges —11.4 16. Sie! sae Wone: [2-22 eee Methane-_-_-___-_- BOG OO eee es eee 189: O)E- ets | eee 18h sie eee Gar aa dioxide} 5:469..8]22-2 6 ore Fe! | nme arp | a ee a D Soe Ale ee a Waterwapor: 22.2 2) jie Sea ay $088.25] ee ee 8; OBOE oc fee 2 eee 7, 508, 2 Balance___________- Teas ae PIRPRDDI Ieee. eos ates peter ter egal encode | 10, 536.2). POtRE So} oa | RE toes, | 27, 851 5 74 (CGS eT | ees va 24, 365. 3) 24, 365. 3]_.--.._--- 21, 862. 2) 21, 862. 2 1 The balance of water has reference only to the two days spent in the respiration calorimeter. TABLE V.—Dry matter per day and the balance of water—Cow 615 Period I Period II Period III Water ! Wat Ww ia ater Dry ater Dry ater matter | Income | Outgo | ™9*tT | income | Outgo | @2%F | Income | Outgo Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams | Grams Alfalianhay = 22.0: .. 2, 993. 0 156: 0) 2c see 3, 018. 4 204; Ol 52s 3, 038. 2 O47. 0}: eS Grain mixture___-__ 4, 447.8 652.0) fee ere 4, 403.1) CGN Tak dt tad 4, 365.8 699. Qi ere ee 2. eS es | oe G40: Ol: en ee JIE ane al 203130) 0) ac Bees nes 82110: Ole ne Set ee Ee eee 2, 450. 1} 2,4 <tr ape eee se co Ns 13, 842.0{ “aly ane MSH Maa oe | ail 14, 410.4 Hatt and brushings- p Ay ( eee ae tees 8 ye 2056 |< 2 Ge} IS Sjosrees 122 Lo SA ee oes : (Glan 2 6, O8649i0 O40. 7a eB SOs Oe Riese ees tarection for COsz: 1h <:) re —19.4 7 AS: |e Saseeeere —21.1 3052). —22.5 P55 Ree = ee Methane..._-__- ABO SO] ee I ee 18t 4 ite ce ee i be Ua | RE IR NEI Sa Carbon) dioxides|'775; 16515)6 2 | eee LARS Fie || (Serene (ae oP 5; 469.4). ons eee Water vapor seei}- <5 2s] | GUGAz.6|. 0 ey a: GorsRo5 path oe eee] 6, O88. 6 RS AIANCR Ye Eee Ae el 18, 851. 8) Boe 2 8b ee cat 3: 200412 os See meys 8. 17, 546. 5) ies = ss ee 7A Ee haere PE SI | 26, 527. 6| 26, 527.6)... | 24, 330. 6| 24, 330.6]... 26, 734.7) 26, 734.7 1 The balance of water has reference only to the two days spent in the respiration calorimeter. TasBLeE VI.—Dry matier and the balance of water—Cow 579 | Period I Period II Wat Water Dry ater Drs ate matter | Income | Outgo | ™#*el | Income | Outgo Grams | Grams | Grams | Grams | Grams | Grams mulaia ny CEE 8 AP ee Pe eee ae 3, 346. 8 364. Oho pee 3, 368. 7 yA A) Fees ees. Gratnimixture:. 2-2)... 40... 2 ak. f.e 4, 820. 6 SOOO. = ae | 4,806.0) 752.0.) 22 loeeen VEEL areas Sane cre apres one nb Sietecey sien med I ection ne 45: FOO: Oeies ee eek aad 10) 400, 0°} sc coe eesee MCCBSES obi ee) UU 3 ae ee 2,481.8 = if 2, 529. Made 5a aay) ae 544.6 \ ---2----- 14, 778. 6 { 492. 6 |f--------- 14, 890. 0 GUTS DUS DNS! oe ee ss See 46-6 Joceeedencs 1.2 DOM eC cet 1.0 Lit Ss ee eh ee | Se oe Lhe ee 19184, 5518. = 2 | 7,269.5 1,440.8 [2 ee | 6,805.7 Correction for CO2 Witter es A A —19.8 Petes | oe ee —23.3 | ey ee Se ee IVS Ruane ce Rs Cb ye eee yt ee Fd STE, i eee cos 212. : ERE |p Co: € WarponiGiGxiG@s. 2325. 442-6 eee cst 21s ta Ree [he eae sa ake, his ra Dene. 6, 85701 |occtseo eee When WADOr f2c un ak ae eee ee [Ree NN eee se Pale tc Ua Yt RS ay [Sas SR 6, 832. 1 LOLS Tc ae RS SEES ye A fi actos PL iy 61 id nas ot [Pea el | 17, 0864 [o-- Seo Birt Wk se AON ae a eg oe 29, 665.3 | 29, 665.3 |........-- 28, 528.8 | 28, 528.8