VI B R.AFLY OF THE UNIVERSITY: OF ILLINOIS' G30.7 WGb cop - 2. AGRICULTURE NOT/CE: Return or renew all Library Materials! The Minimum Fee for each Lost Book is $50.00. The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Then, mutilation, and underlining of books ^^ nary action and may result in dismissal from the Un To renew call Telephone Center, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN L161 0-1096 UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN NO. 283 A TECHNICAL STUDY OF THE MAINTENANCE AND FATTENING OF SHEEP AND THEIR UTILIZATION OF ALFALFA HAY BY H. H. MITCHELL, W. G. KAMMLADE, AND T. S. HAMILTON URBANA, ILLINOIS, DECEMBER, 1926 WHILE the methods of study and the results secured in this in- vestigation are mainly of a technical nature, the sheep raiser will be directly interested in several of the facts established: 1. The feeding of alfalfa hay alone was continued for 133 days with six sheep and 308 days with six others, with no apparent indica- tions of harmful effects. 2. Sixteen percent of the gain in live weight was due to "fill." 3. A comparison of the results secured in this investigation with the results secured in investigations with steers indicates that these two species of animals are about equal in their ability to utilize the metabolizable (or available) energy of alfalfa hay in fattening. 4. Approximately 2.3 pounds of alfalfa hay per day per 100 pounds of live weight maintained ten- to fourteen-months-old western lambs at constant weight for 133 days. Amounts greater than this must be fed to allow for growth and fattening. 5. The daily growth of wool during the fattening period contained only .015 of a pound of protein for a sheep weighing 100 pounds. 6. In the total increase in "empty" weight during fattening 60 percent of the dry matter, 34 percent of the protein, 73 percent of the fat, 47 percent of the mineral matter, and 66 percent of the gross en- ergy were added to the dressed carcass, mainly to the boneless meat. The wool grown contained 23 percent of the dry matter, 60 percent of the protein, 52 percent of the mineral matter, 6 percent of the fat, and 14 percent of the gross energy contained in the added weight. A TECHNICAL STUDY OF THE MAINTENANCE AND FATTENING OF SHEEP AND THEIR UTILIZATION OF ALFALFA HAY BY H. H. MITCHELL, W. G. KAMMLADE, and T. S. HAMILTON 1 Precise information concerning the nutritive requirements of sheep for either maintenance or fattening is difficult to find in the literature. In his book, "The Nutrition of Farm Animals," Armsby quotes a few experiments bearing on the maintenance requirement of sheep, most of which, however, were not so planned as to give the informa- tion desired by direct calculation. Slaughter results on sheep, from which the composition of gains in weight may be computed, are also few in number. The only com- plete analyses of the entire carcasses of sheep in different stages of fattening seem to be those of Lawes and Gilbert 2 published in 1859. Partial analyses of carcasses of sheep have been reported by other investigators, but such results cannot be used in the com- putation of the composition of gains in weight without the use of assumed values for the composition of the unanalyzed parts. Further- more, the question of the utilization of feed energy by fatten- ing sheep has been practically untouched except for a few computa- tions by Armsby 3 based upon the results of a series of respiration ex- periments upon two sheep by Kern and Wattenberg. The usual as- sumption that Armsby 's net energy values of feeds apply to sheep as well as to cattle seems to rest entirely upon these few computations. It was the purpose of the experiment reported in this bulletin to throw some light upon these questions relating to the nutrition of sheep. OUTLINE OF THE EXPERIMENT To simplify the calculations of the experiment and to give the re- sults a more definite significance, the ration used thruout the experi- ment was alfalfa hay alone. *H. H. MITCHELL, Chief in Animal Nutrition; W. G. KAMMLADE, Assistant Chief in Sheep Husbandry; T. S. HAMILTON, Associate in Animal Nutrition. "Armsby, H. P. The Nutrition of Farm Animals, 653. 1917. 'Armsby, H. P., and Moulton, C. R. The Animal as a Converter of Matter and Energy, 42. 1925. 223 224 BULLETIN No. 283 [December, Twelve western lambs, about ten months of age at the beginning of the experiment, were placed upon a maintenance allowance of al- falfa hay on February 15, 1923. The sheep weighed close to 100 pounds per head, the variation in weight ranging from 90.5 to 104 pounds. Each sheep was fed individually and allowed 2 pounds of alfalfa hay daily regardless of its weight. After a preliminary period of three weeks, during which time the body weight became adjusted to the food intake, the maintenance experiment was considered to have started. In the course of -this experiment, which lasted 126 days, each sheep was subjected to a digestion and metabolism test of 7 days' duration, to determine the intake of digestible nutrients and metabolizable en- ergy. The feed records of this period, together with the results of the metabolism studies, permit a computation of the amount of metabol- izable energy in alfalfa hay required for the maintenance of sheep. At the end of the maintenance period 6 of the 12 sheep were slaughtered and their entire carcasses analyzed to determine the con- tent of nutrients and gross energy. The remaining 6 sheep were put upon increased amounts of alfalfa hay, permitting a certain amount of fattening. During this fattening period each of the sheep was again subjected to a digestion and metabolism trial of 10 days' duration, and at the end of 182 days, during which the sheep gained from 18 to 42 pounds in w r eight, they were slaughtered and analyzed. The results of the analysis of the fat sheep, compared with the re- sults of the analysis of the maintenance sheep, permit a calculation of the composition of the gains. The energy, protein, and ash content of these gains is a fair measure of the energy, protein, and ash required to produce them. The feed records of the fattening period, in comparison with the feed records of the maintenance period, permit a computation of the amount of alfalfa hay consumed during the fattening period above the maintenance requirement. The metabolism studies permit the computation, from these feed records, of the metabolizable energy required for maintenance and, in the fattening experiment, the con- sumption of metabolizable energy above the maintenance require- ments. A comparison of these results with the gross energy of the gains secured permit the computation of the net availability of the metabolizable energy of alfalfa hay for fattening. The alfalfa hay was sampled each day thruout the feeding tests, and was analyzed at somewhat irregular intervals, with the results show r n in Table 1. THE MAINTENANCE EXPERIMENT The pen in which the lambs were allowed to exercise was approx- imately 1 by 5 rods. Water and salt were provided ad libitum. Each lamb was fed in an individual section of a feed rack located in a shed open toward the south. The lambs wore straps about their necks, to FEED REQUIREMENTS OF SHEEP 225 which were attached number tags for identification and iron rings; the rings were used in tying the lambs in their proper section of the feed rack. Except at feeding time, the lambs were allowed the run of the open pen. The period during which the body weights of the sheep were main- tained at approximately constant level on constant feed consumption TABLE 1. CHEMICAL COMPOSITION OF THE ALFALFA HAY USED THRUOUT THE EXPERIMENTS Dry Crude N-free Ether Gross Dates sub- pro- ex- ex- Ash Crude energy stance tein tract tract fiber per gram perct. perct. perct. perct. perct. perct. small cols. Mar. 2-May 31 92 18 15 38 39 51 1.64 6.60 29.05 4 126 May 31-Julv 16 91 71 14 42 41 40 1 81 6.44 27.64 3 978 July 16-Sept. 10 92.89 17.56 38.07 2.24 6.81 28.21 4 192 Sept. 10-Oct. 9 93.43 17 02 42.38 2.27 8.91 22.85 4 125 Oct. 9-Nov. 12 94 41 14.84 41 72 2 04 7.40 28.41 4 112 Nov. 12-Jan. 7 93.33 15.50 37.83 1.64 6.88 31.48 4 161 Average for mainten- ance experiment 92.0 15.1 40 1 1.7 6.5 28.6 4 077 Average for fattening experiment 93.4 16.3 39.4 2.0 7.3 28.4 4 155 lasted from March 5 to July 9, a total of 126 days. On July 9 six of the sheep were placed upon increased amounts of alfalfa hay. How- ever, since it was not convenient to slaughter the remaining 6 animals on this date, they were held over for a week on the same intake of feed, so that the maintenance trial with these sheep lasted for 133 days. The weekly weights of the 12 sheep in the maintenance experi- ment are given in Table 2. The interpretation of these results is some- what complicated by the fact that it was found necessary on May 1, when the maintenance trial was only about half complete, to shear the sheep, because of the increasingly warm weather. Tho the body weights were thus reduced by amounts varying from 4 to 9 pounds, there seemed to be no tendency for the sheared sheep to increase in weight on the same amount of feed. The blank spaces in the table represent those periods during which the sheep were in the metabolism crates. The metabolism periods were of 7 days' duration, the sheep being handled in groups of three, since only three metabolism crates were available. The crates used were modeled after those which E. B. Forbes used in his numerous nutrition experiments on swine. In ap- plying these crates to metabolism work on sheep, it was found advis- able to increase the size of the windows and to put a window on each side of the crate, so that the sheep could see each other during the trial. 226 BULLETIN No. 283 [December, TABLE 2. WEEKLY WEIGHTS OP SHEEP DURING MAINTENANCE EXPERIMENT (All weights in pounds) Sheep No. . . 142 143 144 145 146 147 148 149 150 151 152 153 1923 Mar. 5 98 9?! 92 95 101 99 89 97 91 92 91 95 Mar. 12.... Mar. 19.... Mar. 26.... Apr. 2 96 98 97 96 91 92 94 94 92 92 94 93 97 98 99 96 101 100 101 103 96 97 98 101 89 89 90 91 96 97 99 98 90 91 92 93 90 93 94 93 90 92 94 94 94 93 94 93 Apr. 9 96 94 91 96 99 99 88 97 92 94 92 94 Apr. 16 Apr. 23 May I 1 May 7 102 97 96 97 95 86 95 95 89 10(f 98 95 94 104 102 93 92 102 100 95 93 93 92 88 85 104 101 94 92 97 95 88 87 97 96 89 88 97 97 97 89 95 95 97 89 May 14. . . . May 21 92 89 84 81 86 83 '86 '85 '87 86 93 87 89 85 90 87 87 87 May 28. .. . June 4 93 91 85 82 88 84 93 90 90 86 92 88 88 83 89 88 87 83 June 11. . . . June 18 June 25 .... July 2 July 9 July 16. . . . 88 93 98 87 91 85 81 83 87 78 83 8? 83 84 88 82 84 86 90 94 87 90 87 87 91 84 88 82 89 91 93 89 91 80 83 84 79 81 76 89 89 93 87 88 83 83 88 80 83 78 84 85 86 81 84 78 86 86 89 84 85 84 86 87 83 85 Fleece weights. . 6.5 7.0 6.0 4.0 9.0 7.5 6.5 7.0 7.25 7.0 7.0 7.0 *A11 sheep were sheared on May 1, except the last three, which were sheared on May 7. The weights on the date of shearing and on all subsequent dates are ex- clusive of the weights of the fleece removed. TABLE 3. COEFFICIENTS OF DIGESTIBILITY OF ALFALFA HAY FED AS A MAINTENANCE RATION Sheep No. Dry substance Crude protein N-free extract Ether extract Crude fiber 142. . perct. 55.6 perct. 67.4 perct. 72 A perct. 8.6 perct. 20.0 143 58.7 68.2 75.1 9.2 26.7 144 57.3 67.5 70.9 7.2 30.3 145. . 55.7 68.9 68.5 12.0 30.8 146 58.2 68.3 71.7 27.4 34.1 147 59.5 68.4 72.7 26.4 36.5 148 53.2 64.5 70.7 41.1 19.3 149 57.2 68.0 71.9 34.3 28.7 150 54.8 65.3 69.1 45.5 25.7 151 51.8 67.9 69.0 13.0 20.2 152 53.3 67.0 70.9 3.0 22.5 153 51.8 66.4 69.6 0.0 20.3 Average 55.6 67.3 71.0 19.0 26.3 1926'} FEED REQUIREMENTS OF SHEEP 227 Under these conditions they were much more tractable. Another mod- ification of the Forbes crate was the substitution of a copper wire screen of fine mesh for the cloth used by Forbes to retain the feces. This screen seemed to be much more easily washed in the small vol- umes of water advisable for this work than was the cloth originally rec- ommended. Altho these copper screens will tarnish in time, there is no reason for believing that the composition of the urine draining thru them is appreciably changed. During the metabolism test the sheep re- ceived the same amount of alfalfa hay as they had been consuming for a number of weeks and the alfalfa hay was approximately of the same quality. The detailed results of the digestion and metabolism experiments are given in the Appendix. A summary of the coefficients of digesti- bility computed in the ordinary fashion is given in Table 3. The in- dividual coefficients are fairly constant among themselves with the ex- ception of the coefficients for crude fat (ether extract). The small amount of ether extract in alfalfa hay and the large amount in the in- testinal secretions renders an accurate estimate of the digestibility of the ether extract of alfalfa hay difficult, if not impossible. There was no refused feed in any of these digestion trials. An estimate of the metabolizable energy of the alfalfa hay was rendered possible by the fact that the urine, as well as the feces, was ^collected, and that the energy content of feed and excreta was directly determined in the bomb calorimeter. The nitrogen content of the urine was also determined for the purpose of obtaining a determination of the nitrogen balances. By means of the nitrogen balance the metabol- izable energy of the hay can be corrected for protein stored in the body or protein catabolized from the body. 1 In Table 4 the various stages in the computation of the metabolizable energy of the alfalfa hay are given. The methane output of the sheep was computed from the amount of digestible carbohydrates consumed, Armsby's factor of 4.5 grams of methane per 100 grams of digestible carbohydrates being used. From this table it will be seen that the average percentage of the gross en- ergy of the alfalfa hay that was metabolizable was 42.9, a figure agree- ing closely with that obtained by Armsby in experiments on steers, ref- erence to which will be made later. The metabolizable energy was computed to be 1.69 therms per pound of digestible organic matter, a figure somewhat larger than the average figure Armsby gives for roughages, namely, 1.588 therms. During the maintenance experiment only small amounts of feed were refused, less than 2 percent of the feed offered in all cases. The refused feed consisted mainly of small pieces of stem, but on account 1 Armsby, H. P., and Fries, J. A. U. S. Dept. of Agr. Bur. of Anira. Indus., Bui. 101, 31. 1908. 228 BULLETIN No. 283 [December, h I rg aboli 8 CO CN CN CD CO CO OS OS lO OS i. i ." COCOCO t^-t^-00 COOCO CO be si < S 8 5 G a ? os o o oo 56 os as o o oor^t^- os - O C fc ... ... ... . oj i-H CN CN i-Hi-li-l rH gjj I >O CO CO OS 00 CO CO CN OS i-H lO 00 OS ^ I CO CO (NIC 1 * ^H OS OS CN 'a g co oo co oscoco oo * t- O os oo 00 H- +? ?~ CN O t^- CO i I i OOOt^- CO i I C^ i I Q I CN o Tf ^H o co * o * 3 Fooo ooo ooo OO^H o t, >-. -7 C S S.2^ 03 ^+ + 4- I ++ + i -r-r-r -r ^ 'S ^ fl 22 o ^ **?* 2 r* ^^ ^o '^ co ^^ *o CNI ^^ co co co co ^^ Q 2 M ~ .OOOOCO CO^C^ CNtO OOOS OC !*- FrtirtiTti *** COCOCO COCOi-H CO M4 4> Oj CO * 00 O rt* ^H lO CD 00 1C OS OS O_ J3 I 1-1 I-H CN I-H I-H (M I-H ,-H CN CN CN CN ^ 8 CN CN CN 00 00 00 O g rt^w wCpcpcp y?^?^? cpcpcp icioto cp . O Q CO t^ O 1C 00 * rf< b- CN * i-H o aj~H"S. WCOOOO OO3O CNbT}< CN^CN CD bCoS'S ^ *-? rv * co r*- co co co t^ co co co CD co co co .a 8 " COCOCO OSO5OS '*rf>^ 00 00 00 00 00 00 OO 00 00 b- l~- t> 00 j-j i~ i- i~ !COiO IO>OO lOiC^O *O S ta 01 g c "8 s s ^^ ^ ^ OOOSO^HCNCO C ^^ T^ ^^ ^^ ^ ^n ^^ ^* iO *O *O ^O *j O 229 of the small amount of such refused feed thruout the test, the compo- sition of the feed consumed was practically the same as the average composition of the alfalfa hay offered. A summary of the more important results of the experiment rel- ative to the feed requirements for maintenance are given in Table 5. TABLE 5. AVERAGE RESULTS OF THE MAINTENANCE EXPERIMENT Data for sheep slaughtered at end of experiment Sheep No 142 143 146 148 150 151 Days on experiment 133 133 133 133 133 133 Average live weight Ibs. 90 8 to*. 82.7 Ibs. 86.8 Ibs. 82.6 Ibs. 84.0 Ibs. 84.6 Total feed offered 266.0 266.0 267.4 266.0 266.0 266.0 Total feed refused 5.9 3.7 5.0 3.8 1.4 3.4 Total feed consumed 260.1 262.3 262.4 262.2 264.6 262.6 Average daily feed consumed 1.96 1.97 1.97 1.97 1.98 1.97 Feed consumed per day per 100 pounds live weight: Computed by weight ratio 2 16 2 38 2.27 2 38 2 36 2.30 Computed by surface ratio 2.10 2.24 2.16 2.24 2.22 2.23 Metabolizable energy per day per 100 pounds weight Computed by weight ratio cals. 1 697 cals. 2 007 cals. 1 914 cals. 1 862 cals. 1 959 cals. 1 772 Computed by surface ratio 1 650 I 888 1 821 1 752 1 843 1 671 Data for sheep fattened at end of experiment Average Sheep No 144 145 147 149 152 153 of 12 sheep Days on experiment 126 126 126 126 126 126 Ibs. Ibs. Ibs. Ibs. Ibs. Ibs. Ibs. Average live weight 84 7 89 3 90 89 4 86 4 85 4 Total feed offered 252.0 252.0 254.8 252 252.0 252.0 Total feed refused 1.0 0.0 .6 .5 3.3 2.4 Total feed consumed 251 252 254 2 251 5 247 8 249 6 Average daily feed consumed 1.99 2.00 2.02 1 99 1.97 1.98 Feed consumed per day per 100 pounds live weight Computed by weight ratio 2.35 2.24 2.24 2.23 2.28 2.32 2.295 Computed by surface ratio .... 2.22 2.16 2.17 2.14 2.17 2.20 2.185 Metabolizable energy per day per 100 pounds weight cals. cals. cals. cals. cals. mix. cals. Computed by weight ratio. . . . 1 925 1 735 1 806 I 798 1 665 1 707 1 820 Computed by surface ratio. . . . 1 819 1 673 1 749 1 725 1 585 1 619 1 733 The final requirements have been expressed in terms of feed consumed and metabolizable energy used per 100 pounds live weight, and have been computed from the actual experimental results both by the simple weight ratio and by the surface ratio, that is, the ratio of the two- thirds power of the body weight. Since the average weight of the sheep was fairly close to 100 pounds in all cases, the results of the two methods of computation are closely similar. The amount of alfalfa 230 BULLETIN No. 283 [December, o > T 1 i i &; oo ic o o t~- oo-* O3 O~(MOO 00 o C75 .4; 1C CO I-H COCO Oi (~- CD 1C t>- ( ^ t- < CO rH_ (N rH C5 ^ 000 CO s~** ^^ OO ^C '' ^IC t s O^ 1 1 O5 cc O5 CO O CO Tt< ICI>CO (M CC >C CO i-H co Ji 5 * co I-H ic 1C O5 CO CD 1C CD (M OO l ^ CO r-^ (N rH -_x2x o Ci so 03 O5 O5 CO (N OS O5 ^~^ T^ co ^f '^^co i >O 00 33 00 I 1 CO -sa * co c t^ 00 CO CO (N CD (N t^ CO ci ^^ cs. r OO CO 00 CO ^^ 1C 00 CO '-^l> 1C CO oc co 00 Tf O O5 CO Oi I-H t^ (N <*! * CO rH _f[ 3* COCO rH -* * OOl^CD 00 O (M t> ^ CO 1-1 C^S X i-H 1C "* CO CO ' * O5 00 CO '-"^03 O ^C CO 00 ^ CO Oi rH i-H rH T(H CO O O5 i 1 1C Oi rH g ^ COCO rH 1C CO * i-H OO 00 COOSCO^ 1> CO O Ol LC i-H ^""^ OS OO O ' ^ 1C < 5" 00 CO 14 <>5 oo 1C O rH O CO 00-* C 00 l> rH ,_( ^ co CO i-H 00 00 CO C^ (N rH t-S~ (N 1 1 CO w ^ CD O i ' N C^ 1C i4 t"~ * OO co r-4_ CO rH t-~_x M 11 o 2 2 0) "2 43 s r _. bb 3 g -9 a; III i 3 a a? 3 c . ' O} o ^ O *^ a * *_! 6 a, D g 02 1, '53 1 8 1! 1 11 111 Hi 1 !! II !! I oo w^o P^QM o 1926] FEED REQUIREMENTS OF SHEEP 231 hay required per day per 100 pounds live weight, by the 12 sheep, av- eraged 2.295 pounds computed by the weight ratio, and 2.185 pounds computed by the surface ratio. The individual variations from the average figures were very slight. From the individual figures relative to the amount of alfalfa hay required for 100 pounds live weight, from the average gross energy value of the alfalfa hay fed thruout the test, and from the individual percentages of the gross energy which were computed to have been metabolized by the individual sheep, individual values for the metabolizable energy required per day per 100 pounds live weight were obtained. These values averaged 1,820 calories com- puted by the weight ratio, and 1,733 calories computed by the surface ratio. From several live-weight experiments on sheep, Armsby 1 com- putes their metabolizable energy requirement for maintenance to be 1,624 calories, a figure closely approximating our average of 1,733 cal- ories computed in the same fashion. The figures from these live-weight experiments average distinctly higher (23 percent) than similar re- sults computed from respiration experiments, probably because of a greater degree of muscular activity in the experimental animals. The computed requirements of this experiment, and of other live-weight ex- periments, obviously refer to what Armsby has called "economic main- tenance," rather than to "physiological maintenance," the latter term representing a condition of absolute quiet. A summary of the most important slaughter data on the 6 sheep that were killed at the end of the maintenance trial will be found in Table 6. The average dressing percentage of these sheep, on the basis of the chilled carcasses, was 47.23, which is appreciably below the av- erage for sheep in market condition. The shrinkage averaged 2.85 percent, while the cold dressed carcasses contained an average of 75 percent of boneless meat. The contents of the alimentary tract aver- aged 16.7 percent of the live weight, varying from 14.1 to 22.0 percent. The sheep were killed on the morning of July 16 and had received their last feed at about 10 a. m. on the preceding day. The chemical analysis of the carcasses of the sheep was made upon two individual samples, a composite sample of the dressed carcass, and an offal sample, and upon two composite samples for the entire group, namely, the hide and the wool. In preparing the carcass compos- ite sample, the dressed carcass was cut up by the butcher into bones and boneless meat, the separation being as complete as could be made readily with a knife. These two fractions of the carcass were weighed separately and ground finely in a power sausage mill. They were then mixed separately, quartered down, and a convenient composite sample made by combining the ground bone and ground meat in the same pro- portion by weight in which they occurred in the carcass. The offal lr The Nutrition of Farm Animals, 294. 1917. 232 BULLETIN No. 283 [December, sample contained the blood, head, feet, and the viscera with the excep- tion of the kidneys, the latter being included in the carcass composite sample. After putting the head and feet thru a bone grinder, they were ground with the soft tissues in the offal sample and intimately mixed. The fresh pelts were weighed as soon as removed from the carcass and the inner surfaces were painted with a concentrated solu- tion of a sulfid depilatory. The following morning the wool was pulled TABLE 7. PEBCENTAGE COMPOSITION OF CARCASS COMPOSITES OP MAINTENANCE SHEEP Sheep No. Dry substance Crude protein Ether extract Crude ash Unac- counted for Gross energy per gram 142.. perct. 45.47 perct. 17.88 perct. 20.15 perct. 5.70 perct. 1.74 small cols. 2 980 143 43.11 18.94 15.86 5.78 2.53 2 630 146 40 80 19 00 15 09 5 72 99 2 543 148.. 47.06 17.94 22.10 5.15 1.87 3 032 150 41.37 20.13 14.37 5.79 1.08 2 508 151 48 08 17.44 23 81 5.39 1.44 3 343 Average .... 44.32 18.56 18.56 5.59 1.61 2 839 TABLE 8. PERCENTAGE COMPOSITION OF OFFAL SAMPLES OF MAINTENANCE SHEEP Sheep No. Dry sub- stance Crude protein Ether extract Crude ash Unac- counted for Gross energy per gram cr 142. . . perct. 37.04 perct. 14.19 perct. 17.57 perct. 3.61 perct. 1.67 small cols. 2 364 143 34. 88 1 14. 29 1 16. 12 1 3.01 1 1.46 2 410 1 146 31.95 14.94 13.02 2.94 1.05 2 188 148 35.64 13.75 17.78 2.49 1.62 2 679 150 34. 88 1 14. 29 1 16 . 12 1 3.01 1 1.46 2 410 1 151 34. 88 1 14. 29 1 16 . 12 l 3.01 1 1.46 2 410 1 Average.. . . 34.88 14.29 16.12 3.01 1.45 2 410 Samples of offal from Sheep Nos. 143, 150, and 151 were accidentally thrown out before they were analyzed. The average percentage composition of the offal sam- ples of Sheep Nos. 142, 146, and 148 was assumed in these cases. from the pelts, weighed for each sheep, and a sample prepared from the composite wool for the group. The skin was leached with water to remove most of the depilatory. It was then weighed, cut up into con- venient pieces, and put thru the power mill. All of the skins were composited into one sample and analyzed. The change in the water content of the skins during leaching was determined by the difference between the weight of the fresh pelts minus the wool, and the weight of the leached hides. 1926] FEED REQUIREMENTS OF SHEEP 233 All samples were preserved with exactly 1 percent of powdered thymol intimately mixed into the sample, and were kept in the refrig- erator at a low temperature until analyzed. The analytical figures were corrected for this small amount of thymol. The samples were analyzed according to the methods of the Association of Official Agri- cultural Chemists. A Parr oxygen bomb calorimeter was used to de- termine directly the gross energy of all samples. The results of these chemical analyses of the various samples are contained in Tables 7, 8, and 9, and the computed composition of the entire carcass is given in Table 10. The results in Table 10 are given TABLE 9. PERCENTAGE COMPOSITION OF COMPOSITE SKIN AND WOOL SAMPLES FROM MAINTENANCE SHEEP Sample Dry sub- stance Crude protein Ether extract Crude ash Unac- counted for Gross energy per gram Skin perct. 28.87 perct. 20.43 perct. 6.75 perct. 1.70 perct. - .01 small cals. 1 816 Wool 88.60 63.31 8.44 8.94 7.91 4 312 TABLE 10. COMPOSITION OF MAINTENANCE SHEEP ) Sheep No. Weight of sheep Dry sub- stance Crude protein Crude fat Crude ash Gross energy Total Empty kgs. kgs. kgs. kgs. kgs. kgs. therms 142 38.24 31.72 12.72 5.51 5.24 1.44 81.07 143 36.80 28.69 10.93 5.17 3.92 1.24 67.88 146 36.65 31.49 11.74 5.92 4.05 1.41 73.32 148... 33.88 28.95 12.21 5.20 . 5.29 1.19 79.95 150 34.90 28.94 10.97 5.47 3.82 1.30 67.86 151 34.90 29.54 12.39 5.21 5.47 1.27 83.55 Average 35.90 29.87 11.83 5.41 4.63 1.31 75.60 in terms of weights of the different constituents and total therms of gross energy. In Table 11 these weights of constituents are stated as percentages of the empty weight of the sheep, the gross energy being expressed in small calories per gram of empty weight. These carcasses in all cases contained a smaller percentage of fat than any of the car- casses analyzed by Lawes and Gilbert. 1 Since these analyses are of interest mainly in the computation of the gains of the fat sheep, a detailed discussion of them here is unnec- essary. 42. 1925. and Moulton. The Animal as a Converter of Matter and Energy, 234 BULLETIN No. 283 [December, TABLE 11.- -PERCENTAGE COMPOSITION OP MAINTENANCE SHEEP ON THE BASIS OF THE EMPTY WEIGHT Sheep No. Dry sub- stance Crude protein Crude fat Crude ash Gross energy per gram 142 perct. 40.1 perct. 17 A perct. 16.5 perct. 4 5 small cals. 2 556 143 38.1 18.0 13.7 4.3 2 366 146 37.3 18.8 12.9 4.5 2 328 148 42 2 18.0 18 3 4 1 2 762 150 37.9 18.9 13.2 4.5 2 345 151 41.9 17.6 18.5 4.3 2 828 Average 39.58 18.12 15.52 4.37 2 531 TABLE 12. WEEKLY WEIGHTS OF SHEEP DURING THE FATTENING PERIOD (All weights in pounds) Sheep No 144 145 147 159 152 153 1923 July 9 84 90 91 88 85 85 July 16 85 87 91 85 83 82 July 23 91 98 98 95 91 89 July 30 89 95 93 95 92 88 Aug. 6 89 100 94 95 93 88 Aug. 13 90 100 98 97 92 89 Aug. 20 94 105 101 102 100 93 Aug. 27 92 104 99 99 95 92 Sept. 3 95 111 103 106 101 95 Sept. 10 94 106 103 105 99 96 Sept. 17 92 112 105 106 102 96 Sept. 24 97 112 104 107 102 97 Oct. 1 99 112 106 111 103 99 Oct. 8 99 117 104 111 104 100 Oct. 15 100 117 102 110 101 100 Oct. 22 105 120 107 Oct. 29 109 101 100 Nov. 5 117 106 106 Nov. 12 105 125 106 119 110 109 Nov. 19 101 125 104 119 105 104 Nov. 26 104 130 109 120 105 106 Dec. 3 104 126 110 122 106 106 Dec. 10 100 125 109 120 108 105 Dec. 17 97 121 109 121 106 104 Dec. 24 101 127 114 122 108 105 Dec. 31 98 127 115 122 109 102 Jan. 7 '... 101 130 118 127 110 104 FEED REQUIREMENTS OF SHEEP 235 THE FATTENING EXPERIMENT The fattening experiment was started on July 9, 1923, and was continued until it was evident that a majority of the 6 sheep would not put on any more weight on the experimental ration of alfalfa hay alone. In fact, when the sheep were slaughtered on January 7, 182 days after their rations were increased from the maintenance level, 3 of the sheep had been at their maximum weights for the last 8 or 10 weeks, as the weight records in Table 12 indicate. During the fattening of these sheep the attempt was made to get them to consume as much of the hay as possible, since it was realized that under the best of conditions the rate of gain would be small on a ration of roughage alone. -They were started on 3 pounds of alfalfa hay daily and this amount was raised gradually to a level of from 4 to 6 pounds. Toward the end of the experiment it was found expedient to lower these quantities because of the large amounts of refused feed. All refused feed was weighed and collected for analysis in periods cor- responding with those for which feed samples were obtained. In spite of the reduction of feed toward the end of the experiment, increasing amounts of feed were refused. It was found, however, from the chem- ical analyses of these samples of refused feed that while at first the refused feed consisted mainly of stems containing large amounts of crude fiber, towards the last, as the amounts of refused feed increased, ytheir composition approached that of the alfalfa hay offered. The total feed records for the entire fattening experiment, divided into subperiods corresponding with the intervals at which composite feed and ort samples were analyzed, are given in Table 13. In this table the estimated quantities of alfalfa hay consumed do not have any definite significance, particularly in tke later periods of the ex- periment, since the weights of refused feed included an unknown mois- ture contamination from the sheep themselves. In Table 14 the total nutrients consumed by the fattening sheep for the entire period of 182 days are given. These figures were obtained by deducting from the quantities of the chemical constituents in the alfalfa hay offered, the quantities of the chemical constituents in the hay refused. In view of the considerable amounts of alfalfa hay refused in this experiment, there was some danger that the significance of the results would be considerably impaired by the fact that the composition of the material actually consumed by the sheep might be distinctly different from the composition of the alfalfa hay offered. The percentages given in Table 15 were therefore computed, the dry substance rather than the fresh substance being used as the basis of computation. Table 15 also contains the average dry-matter composition of the alfalfa hay offered. The differences in dry-matter composition between the alfalfa 236 BULLETIN No. 283 [December, TABLE 13. FEED RECORDS FOR FATTENING SHEEP (All weights in pounds) Sheep No 144 145 147 149 152 153 July 9 to Sept. 10, 63 days Alfalfa offered 185.5 203.0 185.5 185.5 185.5 185 5 Orts .7 .7 1.2 1.6 1.4 3.4 Consumed 184.8 202.3 184.3 183.9 184.1 182.1 Sept. 10 to Oct. 8, 28 days Alfalfa offered 126.0 154.0 126.0 126.0 126.0 98.0 Orts 5.1 4.5 12.3 4.3 8.6 7.1 Consumed 120.9 149.5 113.7 121.7 117.4 90.9 Oct. 8 to Nov. 12, 35 days Alf alf a offered 175.0 210.0 175.0 175.0 175.0 140 Orts 11.4 11.6 17.2 11.9 14.1 8.4 Consumed 163.6 198 4 157.8 163.1 160 9 131 6 Nov. 12 to Jan. 7, 56 days Alfalfa offered 224.0 280.0 224.0 224.0 224.0 168 Orts 56.7 24.6 46.1 31.2 67.8 31.9 Consumed 167.3 225 A 177.9 192.8 156.2 136.1 Total period, 182 days Alfalfa offered 710.5 847.0 710.5 710.5 710 5 591 5 Alfalfa refused 73.9 71.4 76.8 49.0 91.9 50.8 Alfalfa consumed 636.6 775.6 633.7 661 5 618 6 540 7 Alfalfa consumed, kilograms. . . (289.4) (352.6) (288.0) (300.7) (281.2) (245.8) TABLE 14. TOTAL NUTRIENTS CONSUMED BY FATTENING SHEEP Sheep No. Dry sub- stance Crude protein N-free extract Crude fat Ash Crude fiber Gross energy kgs. kgs. kgs. kgs. kgs. kgs. therms 144.. 27 5 A 49.2 119.4 6.2 22.0 78.6 1 225 145.. . 334. 2T 58.9 144.2 7.4 26.4 97.2 1 483 147.. . 272.9 47.8 117.5 6.1 21.3 80.4 1 212 149.. . 283.2 50.0 122.0 6.3 22.3 82.7 1 259 152.. . 268.2 47.8 111.6 6.1 21.4 81.4 1 192 153.. . 231.5 41.3 99.6 5.2 18.2 67.2 1 033 hay consumed and the alfalfa hay offered seem too small to be of any serious consequence in the interpretation of the feed records. During the fattening period, digestion and metabolism studies were made on each of the 6 sheep. However, the feed consumption during these periods was so variable that no confidence has been felt in the significance of the coefficients of digestibility obtained or in the observed utilization of the gross energy of the feed. 1 The coefficients computed were generally higher than those obtained during the main- *Bul. Natl. Research Council 6, pt. 2, No. 33, p. 20. 1923. 1926] FEED REQUIREMENTS OF SHEEP 237 tenance experiment, and the computed metabolizable energy consti- tuted a considerably higher percentage of the gross energy, i. e., 52 percent. It was decided, therefore, to discard the results of these studies and, in all future computations, to rely upon the analogous results ob- tained during the maintenance experiment. It has been found by other investigators that with rations consisting entirely of roughage, the quantity fed apparently has no effect upon the digestibility. 1 A summary of the more significant slaughter data on the fat sheep will be found in Table 16. The percentage of "fill" on these sheep was very much the same as that on the maintenance sheep. The interval TABLE 15. AVERAGE PERCENTAGE COMPOSITION OP ALFALFA HAY OFFERED TO AND CONSUMED BY THE FATTENING SHEEP FOR THE ENTIRE FATTENING PERIOD (Results expressed on dry basis) Sheep No. Crude protein N-free extract Crude fat Ash Crude fiber Gross energy per gram Alfalfa hay offered All '..... perct. 17.5 perct, 42.2 perct. 2.1 perct. 7.8 perct. 30.4 cals. 4.45 Alfalfa hay consumed 144. . . 17.9 43.4 2.3 8.0 28.5 4.45 145 17.6 43.1 2.2 7.9 29.1 4.44 147 17.5 43.1 2.2 7.8 29.5 4.44 149 17.7 43.1 2.2 7.9 29.2 4.45 152 17.8 41.6 2.3 8.0 30.4 4.44 153 17.8 43.0 2.2 7.9 29.0 4.46 Average 17.7 42.9 2.2 7.9 29.3 4.45 from the time of the last feeding to the time of slaughter, however, was somewhat shorter with these sheep than with the maintenance sheep. The maintenance sheep were fed once daily at approximately 10 a. m. The fat sheep were fed twice daily at approximately 8 a. m. and 4 p. m. The fat sheep were slaughtered on the morning of January 7 and had received their last feed at 4 p. m. the preceding day. The average dressing percentage of the fat sheep was 47.49, a figure very close to the average dressing percentage of the maintenance sheep, in spite of the fact that the fat sheep were in higher condition. However, the fat sheep possessed a heavier coating of wool, averaging 3.47 kilograms, as compared with 1.07 kilograms for the maintenance sheep. The average percentage of boneless meat in the cold carcass was 82.5 as compared with 75.0 for the maintenance sheep. 'Armsby. The Nutrition of Farm Animals, 613. 1917. 238 BULLETIN No. 283 [December, a s EC Q a J DC 1 u ^ , ^ PI !>. ^m H 1C I s * t^* ' ^ ^^ C 15 GO '-OS ^ i 1 03 GO -'. 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