TEXAS AGRICULTURAL lsiPggmkNT STATION i 77%, ‘ A. pazonlink, m . CoKILeQe§$0QEIl§€ A BULLETIN NO. 665 A DECEMBER, 1944 MAINTENANCE REQUIREMENTS OF CHICKENS AND PRODUCTIVE ENERGY OF FEEDS AS RELATED TO‘ AGE G. S. Fraps Division olf Chemistry AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS GIBB GILCHRIST, President E38-145-2500-L180 [Blank Page in Original Bulletin] Diflerences in weight and sex had no effect upon the maintenance require- ‘dents of young chickens per day per 100 grams. Chickens receiving rations i h in protein had much lower maintenance requirements than those receiving tions low in protein. With rations averaging 31 per cent protein the average ‘aintenance requirements was 12.4 calories of productive energy compared till 15.8 calories per day per 100 grams with rations averaging 16.2 per cent tein. In one experiment, chickens in the period from 12 to 18 weeks had average maintenance requirement of 7.12 calories of productive energy day per 100 grams compared with an average of 13.6 calories for chickens the period of 7 to 28 days. The average maintenance requirements of the ’ ng chickens ranged from 5 to 10.8 grams of rations per day per 100 grams. fckens 6 to 18 weeks old utilize the metabolizable energy of feed for pro- action of fat and flesh equally as well as younger chickens. Hydrogenated ' onseed oil with an iodine value of 68 had a productive energy value equal ' y cottonseed oil, but the hydrogenated oil with an iodine value of 10 had a digestibility and the digested portion had about 70 per cent of the pro- ' ‘gctive energy of cottonseed oil. The weight basis was more suitable for calculating maintenance require- ckens in previous work. Differences found in the productive energy values 1' the same feed in two experiments are sometimes due to dilferences in the ‘ntenance requirements between the groups being compared. f nts of chickens up to 18 weeks old, just as it was found to be for young v CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Definitions of terms Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Method of experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maintenance requirements of chickens less than 4 weeks old . . . . . . . . . . . Efiect of individuality, weight and sex upon maintenance requirements. Relation of maintenance requirements to protein content of rations. . Maintenance requirements of chickens to age of 8 to 18 weeks . . . . . . . . . » Productive energy of the feeds with chickens to age of 7 to 19 weeks. . . ._ Productive energy experiments to the age of about 4 weeks . . . . . . . . . . . . .1; Productive energy when maintenance requirements of older chickens calculated on the surface area basis compared with calculations in weight basis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. t ‘ Efiect of variations in energy used for maintenance in the same experim upon the measurements of productive energy . . . . . . . . . . .. " u o o u l OI ‘l ~.< Acknowledgment . . . . . . . . . . . . . . . ._ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~\ ’ ._;_. ‘k AINTENANCE REQUIREMENTS OF CHICKENS AND THE EFFECT OF AGE OF CHICKENS ON THE PRODUCTIVE ENERGY OF FEEDS G. S. Fraps Chief Division of Chemistry i This publication is a part of a comprehensive investigation of the energy g alues of feeds and foods as measured by the storage of fat and flesh by growing ickens. Various aspects of the problem have been presented in previous blications. The energy values of 62 kinds of feed were measured in 192 on young growing chickens (7). Wide differences were found in the ergy values of different kinds of feeds and foods, but these differences were und to be due chiefly to differences in digestibility. The ability of the ickens to utilize the digested material from different feeds, on the average, l: usually uniform. The energy values per unit of the nutrients of many 'fferent feeds are usually within 10% of that of corn meal. Similar results ere found in experiments with rats (8). i The report discusses the variations in maintenance requirements of chickens. t also presents measurements of productive energy made with chickens appre- ably older than those used in previous work (4, 6, 7). A few experiments "th younger chickens not previously reported are included. Definitions of Terms The percentage of effective organic constituents of a feed is the sum of the rcentage of the protein, the nitrogen-free extract and the fat or ether extract ultiplied by 2.25. Crude fiber is disregarded since it is digested only to a ry small extent by chickens, while ash and water have no energy values. 1 The percentage of effective digestible nutrients of a feed is the sum of the vrcentages of digestible protein, the digestible nitrogen-free extract and the gestible ether extract multiplied by 2.25. In other words, the effective , estible nutrients is that portion of the effective organic constituents which v- n be digested by the animal. if Metabolizable energy is the energy of the food less the energy in the ex- ment, both fecal and urinary and, in case of ruminants, in gases produced \ fermentation. It includes all the energy of the food which can be used by e animal. The metabolizable energy of chicken feeds can be calculated by ethods previously developed (5). For the purpose of this work, metaboliz- '-le energy values for maintenance were obtained in calories per 100 grams by ultiplying grams of effective digestible nutrients by 4.2. When part of the a tein is retained, as in growing chickens, the metabolizable energy is higher n for maintenance experiments because the total energy content of protein l‘ higher than its metabolizable energy. Productive energy is the energy stored up as fat and protein by the chicken pm that portion of the ration eaten which exceeds the quantity used for all Fntenance purposes. The productive energy is expressed as calories per Am or per 100 grams of live weight. 6 BULLETIN NO. 665, TEXAS AGRICULTURAL EXPERIMENT STATION Y Cost of utilization of a feed is the difference between the metabol’ energy/and the productive energy of the feed. It consists of the energy g sumed in digesting and utilizing the digested nutrients and in storing the p tein and fat in the animal. If the productive energy is 72% of the PM olizable energy, the remaining 28% is considered to be the cost of utilizatio Maintenance requirement is that portion of the energy of the feed used» the life processes of the animal, including keeping the body warm, and m, ments of the body. The bodily activities consume energy, which in this -‘ is included in the energy of maintenance. \ The productive energy used for maintenance is the difference between productive energy of the quantity of food eaten and the calories of en " stored up in fat and flesh. For the work here presented it is calculated l the data secured with the corn meal ration. a The maintenance requirements in terms of productive energy were calcula according to the equation No. 1: "‘ FRG M=——~ WD In this equation, M is the maintenance requirement in calories per day ” gram, F is the grams of the ration eaten, P is the productive energy of the ra H1’ in calories per gram, G is the gain of calories in fat and flesh, W is the ave j weight of the chicken in grams during the period of the experiment, and D the period of the experiment in days. M is usually converted to calories A 100 grams, to avoid the sue of small fractions. The maintenance requiremA‘ in our experiments is usually calculated from the standard corn meal rati in which the effective digestible nutrients are considered to have the produc energy of 2. 78 calories per gram (4). i‘ The productive energy is calculated by the equation No. 2: MWD+G P=————— F .P is the calories of productive energy per gram of the ration, and M is i maintenance requirement "per day per gram secured from the corn meal rati‘ fed at the same time and under the same conditions as the rations whose p ductive energy is being calculated. The other symbols correspond to L given for equation No. 1. i’ hlethods f The method of experiment has been fully described (4, 6, 7). The o”; chickens were fed a corn meal ration for approximately one week and t’ divided into groups of equal weight, usually of 6 chickens each. The di F“ bilities of the rations fed were measured by means of the chickens left 0' The chickens in one group were killed, prepared for analysis (10) and anal for protein and fat, and the others were fed the experimental rations individu A in battery brooders. At the end of the experimental period, the chic - A r! ‘l f ,. F MAINTENANCE REQUIREMENTS OF CHICKENS 7 were killed and analyzed for protein and fat. The gains in energy were cal- culated from the composition of the chickens at the beginning and at the end f of the experiment. The consumption of feed was ascertained for each chicken. ‘In the first series of experiments (4) the corn meal ration was limited for one group to about half the amount eaten by another group fed unlimited amounts. lBy substitution of the data from the two groups in two equations No. 1 ‘and algebraic solution, the values for the unknowns M, maintenance, and P, pro- ductive energy, were ascertained. In subsequent experiments (6, 7) the corn meal was partly replaced by other feeds in order to compare their productive energy values, while the maintenance requirements were calculated from the data of the corn meal ration fed to another group at the same time. Maintenance Requirements of Chickens Less Than 4 Weeks Old g Little work has been reported on the exact measurement of the maintenance a requirements of chickens, other than reported by us incidental to the determi- lnation of the productive energy of rations and feeds. It may be calculated gfrom the work of Titus (18) that laying White Leghorn pullets require 42 igrams of feed per day per kilogram of body weight. According to the work lof Brody, Fork and Kemster (2) laying hens require 46.5 grams of feed per ‘rday per kilogram. The basal heat production of chickens, according to Mitchell ;and Haines (16) depends on their ages and may range from 146 calories per E-kilogram per day for chickens 5 days old, to 62 calories per kilogram per day lfor cockerels weighing 2728 grams. Barrot, et al. (1) have also reported data ‘don the basal metabolism of chickens. Fraps and Carlyle (4) report as the laverage of a number of experiments that the maintenance requirements are 13.4 calories of productive energy per day per 100 grams during periods of 21 to 42 days for chickens weighing approximately 100 to 500 grams at the end of the period. This was equivalent to 74.8 grams of the feed mixture used, per day per kilogram. Fraps and Carlyle (6) also reported productive energy for maintenance ranging from 10.50 to 16.30 and averaging 12.49 calories r iper day per 100 grams in 20 tests, and (7) from 9.40 to 20.58 with an average ~ lof 14.12 calories per day per 100 grams in 51 experiments and an average of {I360 for 70 experiments. If the ration has the quantity of a productive lenergy of 1.9 calories per gram, the quantity required for maintenance of {chickens up to the age of about 4 weeks ranged from 50 to 108 grams, with an laverage of 72 grams of feed per day per kilogram live weight. On account of Ethe wide range of maintenance requirements, from 9.42 to 20.48 calories per iday per 100 grams, the data was studied further with respect to the factors kwhich might influence the maintenance requirements. The corn meal ration fed to ascertain the maintenance requirements was not Elthe same in all the experiments, but followed the same general pattern. The corn meal ration used in 13 experiments marked A in Table 2 contained, in percentages, corn meal 59.8, wheat gray shorts 16.3, dried skim milk 10.0, yeast 6.0, alfalfa leaf meal 4.0, oyster shell 1.5, tricalcium phosphate 1.0, salt 1.0, cod liver oil 0.2 and manganese sulphate 0.2 6,75, and contained 16 per nt protein. Another corn meal ration marked B in Table 3 contained 10 per ent casein in place of 10 per cent of the corn meal in the above ration but was l 8 BULLETIN NO. 665, TEXAS AGRICULTURAL EXPERIMENT STATION ‘l i otherwise the same. In a third series, Table _5, 20 per cent of casein replacedl 20 per cent corn meal in rations otherwise the same as the ration above. The maintenance requirements were calculated to the average weight of the chickens for the period of the experiment, usually 3 weeks. The calories of‘? productive energy consumed in the ration fed less the calories of energy stored; in the chicken give the calories of productive energy used for maintenance; and with use of the length of the feeding period and the average weight of the, ckickens, the data was converted to calories of productive energy used per day» per 100 grams of live weight. Effect of Individuality, Weight and Sex Upon Maintenance Requirements There are decided differences in the maintenance requirements of different; chickens in the same group, fed on the same ration at the same time and under l, the same conditions. In experiments with 6 groups of young chickens (4) the3 average maintenance requirements of productive energy per 100 grams per. day was 13.7 calories, the average of the maximum for each group was 14.31‘- calories, the average for the minimum was 11 .97 and the average of the standard‘ deviations of the various groups was 1.0. If all the maxima and minima are’? considered separately the variations are still wider. Ritzmen and Benedict (17) have reported variations of from 20 to 80 per cent in the basal metabolism of the same cow or steer. Winchester (19) reports variations in heat productions in laying hens as large as 40 per cent of the maximum heat production. Forbes, et al. (12) point to wide differences in) the basal metabolism of individual rats in the same group of experimental- animals. Fraps and Carlyle (4) give an average standard deviation of 1.0 L calories for 6 experiments with young chickens in which the average main-s tenance requirement was 13.5 calories per day per 100 grams. I Individual variations in maintenance requirements will usually be equalized when groups of sufficient size are fed at the same time, but this equalization- may not always occur. In such cases, differences in maintenance requirementsi; between the groups will cause differences in productive energy which may?‘ not actually be correct. i In order to ascertain the effect of diiferences in weight on maintenance re-l‘ quirements the chickens in each test were divided into three groups: (1) tho appreciably heavier than the average, (2) those approximately average i weight, and (3) those appreciably lighter in weight than the average. The maintenance requirements were then averaged for each group, and then averages? were made for all the tests. The results are given in Table 1. The average‘ difference in maintenance requirements per 100 grams between the chickens) heavier than the average and those lighter than the average is 0.8 calories, for the 17 tests; this difference is small and not statistically significant. In‘ the limits of the weights compared, the weight had no eifect on the maintenance’ requirements per day per 100 grams. Each group was divided according to sex, and the maintenance requirements” averaged for each group. All the groups were then averaged, with the results. shown in Table 1. The experiments were divided into groups, one in which: v Effect of weight V- ‘Effect ‘of sex MAINTENANCE REQUIREMENTS OF CHICKENS 9 Table 1. Average eflect of weight and sex on maintenance requirements Maintenance requirements ca]. /day/1OO gm. Number of tests, 16 I-ligh weight, average 133 gm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 14.3 Low weight, average 104 gm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15.1 Maintenance requirements 15 calories or more per day per 100 gm. Number of tests, 11 Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16. 1 Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.9 Maintenance requirements 12 calories or less per day per 100 gm. Numhbleii of tests, 9 a e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zoio '11 <19 B E’. 6b l-ll-l QI-l the maintenance requirement was 15 calories or more, the other 12 calories or less, per day per 100 grams. As an average of 11 experiments, no differences zin maintenance requirements were shown as due to sex. This applies only to fthe young chickens studied, which were less than 30 days old. According to “iresults published by other workers, sex may cause some differences with older f chickens. According to Ritzman and Benedict (17) some factors connected with the ‘season affected the maintenance requirements of cows. The data for chickens were examined but no relation could be found between the maintenance re- lquirements and the season of the year. ' Relation of Maintenance Requirements to Protein Content of Ration In order to ascertain the relation of the maintenance requirements of the chickens to the protein contents of the ration, the data were tabulated in 4 l!gr0ups——(1) protein content less than 18%, (2) protein content 18.1 to 21%, 5(3) protein content 21.1 to 24%, and (4) protein content over 30%. The constituents of the rations have been given (6, 7). Three sets of rations differed only in the percentages of corn meal and casein. In Ration B, 10% of the corn ‘Tmeal in Ration A was replaced by 10% casein, and in Ration C, 20% corn meal lwas replaced by 20% casein. The period of experiment was 3 weeks. The data are given in Tables 2, 3, 4, and 5, and summarized in Table 6. On _ average, the maintenance requirements are related to the protein content if the ration, being high when the ration was low in protein and low when the tion was high in protein. The chickens which received rations containing over 30 per cent of protein ad an average maintenance requirementlof 12.4 calories per day per 100 grams Nth a standard deviation of 0. 8 compared with 15.9 calories with a standard deviation of 1.9 for chickens which received a ration containing less than 18% if protein. The maintenance requirements of the group receiving rations Table 2. Relation of maintenance requirements to protein in rations containing 18% or les protein Prod. energy used for _ Energy in _ _ maintenance Prod. energy Live weight Fat in chickens, Protein 1Il No. Date begun per day, of ration, at end, chickens, calories rations per 10C0 grams, Cal./gm. gm. 0 per 100 gm. % a . 1-31 December 9, 1930 . . . . . . . ..- . . . . . . .. 20.48 1.980 80.9 8.76 193.2 17.10 1—32 January 13, 1931 . . . . . . . . . . . . . . . . .. 14.91 1.984 148.1 11.11 218.5 17.06 1—33 January 13, 1931 . . . . . . . . . . . . . . . . .. 15.14 1.984 147.8 8.10 191.4 17.06 1-—34 February 11, 1931 . . . . . . . . . . . . . . . .. 15.14 1.984 139.0 14.19 242.7 17.06 5 June 1,1937 . . . . . . . . . . . . . . . . . . . . .. 14.34 1.948 156.8 9.92 195.6 17.38 37 September 23, 1,940—A . . . . . . . . . . .. 16.79 1.925 141.8 8.98 194.4 16.76 38 October 8,1940—A . . . . . . . . . . . . . . .. 16.37 1.964 139.7 10.18 205.1 16.58 42 December 17, 1940——A . . . . . . . . . . . .. 15.59 1.917 209.5 10.49 204.9 16.37 48 April 7, 1941—A . . . . . . . . . . . . . . . . .. 16.09 1.909 215.0 9.59 205.3 16.50 53 _ October 7,1941——A . . . . . . . . . . . . . . .. 15.40 1.937 132.6 8.36 195.5 16.39 54 September21,1941—A............ 15.28 1.937 210.7 11.83 224.7 16.40 56 November 13, 1941-—A... . . . . .. 17.05 1.869 157.2 9.92 208.7 16.20 57 N0vember11,1941——A... 16.85 1.894 161.5 10.33 209.5 16.45 59 January 20, 1942—A.... 17.09 1.979 154.5 8.80 188.0 1.6.20 60 February 3, 1942—A . . . . . . . . .. 16.65 1.952 154.1 10.08 205.8 15.64 62 March 3,1942—A . . . . . . . . . . . . .. 16.09 1.923 147.5 8.22 184.9 15.79 65 May 4, 1942——A . . . . . . . . . . . . . . . . .. 14.01 1.866 169.4 9.54 204.0 15.75 66 May 19, l942—A . . . . . . . . . . . . . . . . .. 12.42 1.890 176.9 12.28 226.2 15.50 Average (18) . . . . . . . . . . . . . . .. 15.87 L936 157.9 10.04 205.5 16.12 Average A (13) . . . . . . . . . . . .. 15.82 1.920 167.0 9.89 204.4 16.19 OI NOLLVLS LNIEINIHEIJXEI "IVHHJIIIIOIHDV SVXELL ‘Q99 "ON NLLEUFIIIH Table 3. Relation of protein to maintenance requirementwProtein in ration containing 18 to 21% protein Prod. energy used for _ _ Energy in _ _ maintenance Prod. xnergy Live weight Fat in chickens, Protein in No. Date begun per day, of ration, at end, chickens, calories rations per 100 frams, CaL/gm. gm. 0 per 100 gm. % Ca . 1-38 Marchv30, 1931 . . . . . . . . . . . . . . . . . .. 9.72 1.973 284.3 12.23 228.4 19.73 1—39 April 3, 1931 . . . . . . . . . . . . . . . . . . . . .. 11.59 1.973 368.3 12.49 236.2 19.73 1-41 April 22, 1931 . . . . . . . . . . . . . . . . . . . .. 9.42 1.973 276.7 14.65 253.6 19.73 1-42 April 29, 1931 . . . . . . . . . . . . . . . . . . . .. 10.97 1.973 407.7 13.12 240.2 19.73 1~62 March 6,1934 . . . . . . . . . . . . . . . . . . .. 16.48 1.799 138.4 8.69 195.3 18.80 1-63 January 21,1935 . . . . . . . . . . . . . . . . .. 13.32 1.747 205.4 9.12 202.0 18.85 1—64 March 11, 1935 . . . . . . . . . . . . . . . . . .. 17.72 l. 46 205.3 7.24 180.4 18.78 1—66 (28 days) June 22,1936 . . . . . . . . . . .. 14.43 1.672 211.7 7.75 189.6 18.13 1 January 4, 1937 . . . . . . . .. 16.37 1.909 118.6 6.52 183.5 19.15 2 February 17, 1937 . . . . . .. 15.35 1.909 147.9 7.80 182.1 19.33 3 March 17, 1937 . . . . . . . .. 15.00 1.919 240.2 7.15 183.8 19.50 4 April 28, 1937 . . . . . . . . . . . . . . . . . . . .. 12.75 1.877 236.9 8.96 193.8 18.78 19 April 17, 1939 . . . . . . . . . . . . . . . . . . . .. 12.34 1.828 187.3 8.30 193.7 20.10 21 October 3, 1939 . . . . . . . . . . . . . . . . . .. 13.13 1.923 209.7 8.71 199.1 20.85 22 October 17, 1939 . . . . . . . . . . . . . . . . .. 12.78 1.933 199.1 9.29 203.1 20.30 25 December 12, 1939 . . . . . . . . . . . . . . .. 15.35 1.767 192.3 5.44 169.3 19.89 33 April 16, 1940 . . . . . . . . . . . . . . . . . . . .. 13.58 1.800 201.7 7.51 188.7 19.36 Average (17) . . . . . . . . . . . . . . .. 13.55 1.872 219.5 9.12 201.3 19.46 II SNHXOIHO JO SLNEIWEIHIIIDHH EIONVNHLNIVN Z1 U5 Table 4. Relation of maintenance requirements to protein in rations containing 21.1—-24% protein a . L" ' E Prod. energy ,.. used for _ _ Energy in _ _ Z maintenance Prod. energy Live weight F_at 1n chickens, Proteln 1n NO- Date begun per day, of ration, at end, chickens, calories rations g _ per 100 frams, CaL/gm. _ gm. % per 100 gm.~ % - C8 . a: O5 P‘ 1—65 April 22, 1935 . . . . . . . . . . . . . . . . . . . .. 14.05 1 991 274.3 6 50 181.8 22.13 H 6 October 19, 1937 . . . . . . . . . . . . . . . . .. 11.10 1 961 191.7 8 81 196.1 21.80 P! 7 -November 23, 1937 . . . . . . . . . . . . . . .. 10.21 1 892 167.7 8 37 192.4 21.55 >4 8 January 25, 1938 . . . . . . . . . . . . . . . . .. 10.20 1 980 209.7 8 04 190.3 22.71 (i; 9 February 22, 1938 . . . . . . . . . . . . . . . .. 12.60 1 979 216.5 6 66 183.7 22.81 10 March 22,1938 . . . . . . . . . . . . . . . . . .. 11.79 1 925 188.9 7 18 182.2 22.81 3° ' 11 May 3, 1938 . . . . . . . . . . . . . . . . . . . . .. 10.50 1 876 212.6 7 38 187.7 22.75 ' 12 May 31,1938 . . . . . . . . . . . . . . . . . . . .. 10 79 1 899 190.5 7 55 189.6 22.08 I-t 13 October 11, 1938 . . . . . . . . . . . . . . . . .. 10 78 1 909 185.2 8 14 189.2 21.40 O 15 December 20, 1938 . . . . . . ..' . . . . . . .. 10.90 1 972 178.7 8 96 195.6 21.92 E 16- January 17, 1939 . . . . . . . . . . . . . . . . .. 11.46 1 952 188.4 8 65 192.8 21.94 ,5; 17 February 14, 1939 . . . . . . . . . . . . . . . .. 11.64 1 970 176.7 8 41 195.1 22.09 Q 18 March 13, 1939 . . . . . . . . . . . . . . . . . .. 10.93 1 962 164.6 8 95 196.2 22.25 g5 30 November 5, 1940—B . . . . . . . . . . . . . . 12.19 1 838 218.0 5 50 174.8 23.55 > 41 November 19, 1940——B . . . . . . . . . . . .. 15.57 1 914 195.5 5 82 173.4 23.69 b‘ 43 January 21,1941—B . . . . . . . . . . . . . .. 13.99 1 924 219.9 6 22 173.8 22.95 m 44 February 4, 1941—B . . . . . . . . . . . . . .. 13.84 1 904 226.6 5 95 178.4 23.71 N 46 March 4, 1941—B . . . . . . . . . . . . . . . .. 13.04 1 865 212.4 6 21 177.8 23.40 n; 47 March 24, 1941—B . . . . . . . . . . . . . . . . 15.86 _ 1 950 207.3 4 75 168.6 23.54 s: 52 September 23, 1941—B . . . . . . . . . . . . 13.49 1 900 202.8 6 56 179.9 22.87 a 55 October 10, 1941—B . . . . . . . . . . . . . .. 12.99 1 863 217.0 6 99 185.2 23.38 g 61 February 16, 1942——B . . . . . . . . . . . . . 15.47 1 888 184.4 4 36 158.3 23.09 63 March 30, 1942——B . . . . . . . . . . . . . . . . 15.52 1 875 229.4 5 09 166.1 23.08 E Average (23) . . . . . . . . . . . . . . .. 12.56 1 921 202.6 7 00 183.0 22.68 m I-l Average B (10) . . . . . . . . . . . . 14.20 1 892 211.3 5 75 173.6 23.33 E O Z Table 5. Relation ol’ maintenance requirements to protein in ration containing over 30% protein Prod. energy used for Energy in ' _ maintenance Prod. energy Live weight Fat in chickens, Protein 1n No. Date begun per day, of ration, at end, chickens, calories rations per 1%) grams, Cal./gm. gm. o - per 100 gm. % a . 23 October 31,1939—C . . . . . . . . . . . . . .. 12.93 1.878 215.6 4.99 171.5 30.71 24 November 28, 1939—~C . . . . . . . . . . . . . 12.45 1.798 188.5 4.46 164.3 30.26 26 January 1, 1940—C . . . . . . . . . . . . . . .. 12.76 1.871 210.6 5.35 166.1 31.61 27 January 23, 1940——C . . . . . . . . . . . . . .. 13.73 1.911 181.6 4.25 160.7 31.38 28 February 6, 1940—C . . . . . . . . . . . . . .. ll .89 1.926 213.9 4.68 166.3 31.26 29 February 20, 1940—C . . . . . . . . . . . . . . 13.01 1.889 196.2 4.39 159.2 30.77 30 March 5,1940—C . . . . . . . . . . . . . . . .. 13.06 1 .896 171.8 3.67 155.4 30.81 31 March 19, 1940—C . . . . . . . . . . . . . . .. 11.75 1.884 207.7 4.83 170.6 30.74 32 April 2. 1940—C. . .. . . . . . . . . . . .. 11.73 1.892 236.5 4.91 167.8 31.80 34 April 30, 1940——-C.. . . . . . . . . . . .. 12.62 1.825 203.8 4.07 165.7 30.15 35 May 14,194(}—C... . . . . . . . . . . .. 10.87 1.816 224.2 4.81 167.0 31.24 36 May 28,1940—C . . . . . . . . . . . . . . . . .. 11.46 1.885 194.0 4.87 166.5 30.80 Average C (12) . . . . . . . . . . . . .. 12.36 1.873 203.7 4.61 165.1 30. SNEDIOIHO cIO SLNEIWGIHIIIDHH EIONVNHLNIVH 14 BULLETIN NO. 665, TEXAS AGRICULTURAL EXPERIMENT STATION Table 6. and fat content of chickens Relation of protein content of ration to maintenance requirements, live we Protein Protein Protein Prote less than 18. 1 to 21 .1 to over 8 % 21 % 24% 307 Number of comparisons averaged . . . . . . . . . .. 18 17 23 Maintenance requirements, calories of pro- A ductive energy per day per 100 gm. . Average . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15.8 13.6 12.6 .~ Maximum . . . . . . . . . . . . . . . . . . . . . . . . .. 20.5 17.7 15.9 .‘ Minimum . . . . . . . . . . . . . . . . . . . . . . . . .. 12.4 9.4 10.2 . ; Standard deviation . . . . . . . . . . . . . . . . . . 1 .7 2.5 2.0 O. 1 Live weight at end, gm . . . . . . . . . . . . . . . . . . . .. 157.9 219.5 202.6 .2033? Fat in chickens, per cent . . . . . . . . . . . . . 10.0 9.1 7.0 4.6 Protein in ration, average per cent.. . . . 16.2 19.5 22.7 Groups on rations in which casein replace corn meal but otherwise the same. Protein in ration, per cent . . . . . . . . . . . . 16.2 . . . . . . . . . . 23 .3 Number averaged . . . . . . . . . . . . . . . . . . . 15 . . . . . . . . . . 10 Average maintenance requirement. . . . . 15.8 . . . . . . . . . . 14.2 containing 30% protein were uniformly low, while those receiving aratii containing less than 18% protein were uniformly high with the exception I experiment 66, in which it was lower than the others. The maintenance requirements of the two intermediate groups, where ~_ rations contained 18 to 21 and 21 to 24% protein, averaged 13.6, and 12i calories per day per 100 grams, and were thus between the high and y The maintenance requirements were, however, mo, variable in these intermediate groups than in the groups which received W’ rations containing 30% protein, the standard deviations being 2.45 and 1. Y‘; respectively. The maintenance requirements in the group receiving 18-21 protein ranged from 9 .42 to 17 .72 calories per day and 100 grams, and for w" The ran low protein rations. receiving 21-24% protein it ranged from 10.20 to 15.86 calories. of maintenance requirements in the two intermediate groups overlaps l, maintenance requirements of the group receiving the high protein rations, a those of the group receiving the low protein ration. Although there is app -; ently some relation between the protein content of the rations and the mai * tenance requirements of chickens, it is clear that other factors affected t maintenance requirements of the chickens receiving rations with nearly t same protein content. Similar results are secured with the chickens receiving the rations whi Q differed only in quantities of corn meal and casein marked A, B and C in Tabl The averages for the entire group and the thirteen tests whi =4, received the same ration were nearly the same with the chickens in the group The two sets of averages are different in the groups in whi i. 21 to 24% protein was fed, the average maintenance requirements in the entire group being 12.56 calories, and in the sub-group, 14.20 calories. nothing in the data to indicate the reason for the differences in these two su a 2, 3, 4, 5. fed 18% protein. groups. The data indicate clearly that the protein content of the ration may afiect. the maintenance requirements of young chickens. The chickens receiving the‘ There is f MAINTENANCE REQUIREMENTS OF CHICKENS 1,5 ' tion containing 30 per cent of protein had uniformly low maintenance re- uirements averaging 12.4 calories of productive energy per day per 100 grams, 1- uivalent to 6. 5 grams of a ration furnishing 1.9 calories of productive energy {~- gram. The chickens receiving rations containing less than 17 per cent of rotein had high average requirements of 15.8 calories of productive energy ~ r day per 100 grams, equal to 8.4 grams of ration. a This effect of protein is contrary to the idea that protein has a specific dynamic f - wer which increases the heat eliminated by animals. Low maintenance i quirements are accompanied by decreased elimination of heat. The observed crease in elimination of heat which comes within a short time after the in- ii; stion of protein evidently does not represent the action of the protein over f e- entire day. While the maintenance requirements were uniformly low with chickens 3 ceiving rations containing more than 30 per cent of protein, and usually high “th those receiving less than 17 per cent of protein, the maintenance require- ments varied widely with the chickens receiving 18 to 21 and 21 to 24 per cent ;~ protein. They also varied with individual chickens fed on the same ration Vt the same time. That is, there are wide variations in maintenance require- _ents not due to percentages of protein but due to causes which are not yet Lccounted for. a Comparison of the averages in Table 6 shows that the chickens receiving the tion containing averages of 30 per cent protein had an average live weight ' t the end of 203.7 grams, compared with 157. 9 grams for those receiving the l tions containing less than 18% protein, and an average fat content of 4.6 mpared with 10.0%. A ration of high protein content produces chickens » larger size and containing much less fat than the rations containing 16% w otein (9). 5- The experiments cited above were made at different times of the year and l- do not involve direct comparisons of the effect of protein on maintenance uirements. Forbes and associates (14) have conducted a series of 6 ex- 1' riments with rats in which the effect of different percentages of protein was From the data summarized by them, (14) the maintenance require- ents of rats were approximately calculated as shown in Table 7. The period f experiment was 70 days. For the purpose of this calculation, the pro- uctive energy of the ration was estimated to be 0.7 of the metabolizable p‘ ergy and the average weight was assumed to be the same as the initial and ' al weights divided by 2. Neither of these assumptions is exactly correct a t the error is not sufficient to invalidate the calculations. g The results summarized in Table 8 show that the maintenance requirements or the young growing rats decreased as the protein content of the ration in- p» ases, up to 25%. The decrease is greatest between 10% and 15% protein »- the ration and is small above 15%. The results are remarkably uniform :1 the 5 experiments. With mature rats the protein content of the ration had ttle if any effect upon the maintenance requirements, in the single experiment ade with such animals. II U Table 7. Elect of percentage of protein on maintenance requirements of rats E L=1 I-J _ _ _ _ _ _ Prod. energy Maintenance E Experiment No. and Llve werght _Prot_e1n Body galn Metabohzed Average Productwe _ for per 100 gm. reference to publicatlon of rats 1n duets of energy energy welght energy mamtenance per day Z * . gm. % cal. cal. gm. cal. cal. cal. ,9 Q O5 .9‘ Exp. 1 40-126 10 224 1933 87.0 1353.1 1129.1 18.5 ,4 J. Nutri. 10 48-155 15 263 1931 101.5 1351.7 1088.7 15.3 (1935), 461 48-168 20 296 1939 103.0 1357 3 1061.3 14.7 a 47-167 25 302 1928 107.0 1349 6 1047.6 14.0 m ‘Exp. 2 48-115 10 226 1858 81.5 1300.6 1074.6 18.8 g> J. Nutr. 10 47-142 15 259 1860 94.5 1302.0 1043.0 15.8 Q (1935), 461 48-150 20 267 1957 99.0 1299 9 1032.9 14.9 a 48-152 25 270 ‘ 1848 100.0 1293 6 1023.6 14.6 g Exp. 3 47—162 25 332 2001 104.5 1400 7 1068.7 14.6 b‘ J. Nutr. 15 47-159 30 320 3 1984 103.0 1388 8 1068.8 14.8 '5 (1938), 285 48-159 35 311 1970 103.5 1379 0 1068.0 14.7 g 47-151 45 285 1934 99.0 1353 8 1068.8 15.4 p, Exp. 4 49-173 l0 364 2739 111.0 1917 3 1553.3 20.0 b‘ J. Nutr. 18 50-218 25 480 2698 134.0 1888 6 1408.6 15.0 P1 (1939), 47 50-220 35 423 2648 135.0 1853 6 1430.6 15.1 Q 50~207 45 415 2577 128.5 1803 9 1388.9 15.4 m Exp. 5 385-391 10 113 3619 388.0 2533 3 2420.3 8.9 g J. Nutr. 20 388-401 25 124 3579 394.5 2505 3 2381.3 8.6 H (1940), 47 390-388 45 5 3407 389.0 2384 9 2379.9 8.7 z Exp. 6 34-146 10 323 2179 90.0 1525 3 1202.3 19.1 a J. Nutr. 28 33—202 25 387 2157 117.5 1509 9 1122.9 13.7 g (1944), 194 33480 45 334 2028 106.5 1419 6 1085.6 14.6 > H i-Il O Z ‘. . MAINTENANCE REQUIREMENTS OF CHICKENS Table 8. 17 Elfect of protein in ration on maintenance requirements of rats as calculated from the work of Forbes, et al. Maintenance requirements in calories per 100 grams per day _ _ Exp. 1 Exp. 2 Exp. 3 Exp. 4 Exp. 5* Exp. 6 Protein 111 rations Cal. Cal. Cal. Cal. Cal. Cal. 10% . . . . . . . . . . . . . . .. 18.5 18.8 . . . . . . . . .. 20.0 8.9 19.1 15% . . . . . . . . . . . . . . .. 15.3 15.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20% . . . . . . . . . . . . . . .. 14.7 14.9 . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . .. 25% . . . . . . . . . . . . . . .. 14.0 14.6 14.6 15.0 8.6 13.7 % . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . .. 14.8 15.1 . . . . . . . . . . . . . . . . . . .. % . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 14.7 15.4 . . . . . . . . . . . . . . . . . . .. 45% . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15.4 . . . . . . . . .. 8.7 14.6 ‘FExperiment 5 was made with mature rats weighing about 390 grams. Maintenance Requirements of Chickens to Age of 8 to 18 Weeks The work discussed in the preceeding pages was based on experiments to t’ ascertain the productive energy of foods with chickens up to the age of about 4 weeks. ages of 9, 13, and 19 weeks. The methods used have already been described. In the work now to be discussed the experiments were continued to The chickens were about 1 week old when placed on experiment, and the ex- i perimental period lasted 6, 12, or 18 weeks. The corn meal ration used in Experiments 45, 49, 51 and 58 consisted, in percentages, of corn meal 60, wheat gray shorts 16.3, dried skim milk 10, j_ yeast 6.0, alfalfa leaf meal 4.0, calcium carbonate 1.5, tricalcium phosphate . 1.0, salt 1.0, and fortified cod liver oil 0.2. was about 16. 8%. 145 were the same except that they contained 2% less corn meal and 2 per cent 3 more alfalfa leaf meal. 1' to those used in Exp. 45, except that 10% cottonseed meal and 15% cottonseed ' oil replaced 25% corn meal (protein in the ration, 18.5%); in Experiment 64, i, 30% casein replaced 30% corn meal (protein 37.7%). Ti in Experiment 14 contained, in percentages, corn meal 56.8, wheat gray shorts _- 20.0, casein 12.0, yeast 2.0, alfalfa leaf meal 6.0, calcium carbonate 1.0, tricalcium phosphate 1.0, salt 1.0, fortified cod liver oil 0.2 (protein in ration . 21.9%). In experiments numbered above 47, 0.2 gm. manganese sulphate p’ replaced 0.2 gm. wheat gray shorts. ; which replaced the corn meal are shown in the tables. position of the feeds are given in Table 9. The effective organic constituents § of the rations are given in Tables 14 and 15. Table 9 also contains the chemical The protein content of this‘ ration The corn meal rations used in Experiments 125, 131, 139, The corn meal rations used in Exp. 20_were similar The corn meal ration The quantities of the experimental feeds The percentage com- composition of the corn meal rations used in the experiments made for 12 to 18 weeks. Digestion experiments were made on the rations and the effective f digestible constituents were calculated from the digestion coeflicients and the _' analyses of the ration. .' The average live weights, percentages of protein and fat and calories per 100 grams of chicken, as well as other data, are given in Table 10. The data j from each individual chicken were calculated separately in all the work, but only the averages are presented. 81 Tflble 9- P91191111“ Fflllposition of feeds and cornmeal rations, and of feathers w C! F‘ , Nitrogen E} Name of feed sample Proteln Ether Crude free Water Ash a extract fiber extract E % ' % '70 % % % z O Albumen, blood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 70,60 _73 _17 5,64 10,11 12,75 Albumen, egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79.97 .19 .24 5.44 9.11 5.05 a: Casegn, Exp. 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 82.83 ,32 ,15 3,79 8,93 3.98 F‘ _ Casegn, Exp. 49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 82.69 .75 .17 3.54 8.81 4.04 a Caseln, Exp. 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 81.43 .25 .24 5.99 8.62 3.47 111 Corn meal, Exp. 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ._ 10,45 340 1,02 73,45 10,46 1,22 p4 Corn meal, Exp. 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10.81 3_23 ,96 73,99 9,69 1.27 > Corn meal, Exp. 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10.00 3.58 1.10 73.25 11.04 1.03 m Corn meal, Exp. 5O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9,93 4,27 1,35 70;40 12.10 1.45 g, Corn meal, Exp. 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10,19 4,20 1,49 71,09 11,62 1.41 Q Corn meal,‘ Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.55 3,69 1,51 73 67 11.39 1.19 a Corn meal, Exp. 64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9.38 3.96 1.51 73.19 10.66 1.30 Q Corn meal, Exp. 125-131 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9.93 4.85 2.12 69.66 11.86 1.58 c: Cottonseed meal, Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 42.98 5.79 10.13 26.95 7.85 6.30 1"‘ Gelatine* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.98 .05 .15 .00 14.32 1.89 *5 Oat hulls, Exp. 50 and 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.45 1.27 30.04 50.40 7.37 7.47 g Wheat bran, Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19.28 2.84 10.57 49.64 10.56 7.11 a, Wheat bran, Exp. 12 —13l . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19.15 3.66 8.40 52.89 10.66 5.24 L-q Corn meal ratlon, Ex . 14. .. . . . . . . . . . . . . . . . . . . . . . . . .. 21.91 3,22 2.05 57.17 9.58 5.47 Corn meal, cottonsee oil ratlon, Exp. 20 . . . . . . . . . . . . . .. 18.51 17-13 3'56 4729 6'83 6-63 F1 Corn meal ratgon, Exp. 45 . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16.83 3.10 1.91 62.82 9.71 5.63 f; Corn meal ratgon, Exp. 49 . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16.28 3,32 2.48 60.46 10.84 6.12 L,’ Corn meal ratgon, Exp. 51 . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16.16 3.46 2.65 60.78 10.40 6.55 56 Corn meal ratgon, Exp. 50 . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23.65 3.24 2.34 53.55 10.70 6.52 ** Corn meal ratgon, Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15,76 3,35 2,55 62,58 9.74 6.02 g Corn meal ratyon, Exp. 64 . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37.73 2.08 2.50 41.62 8.81" 7.26 z Corn meal ratgon, Exp. 125-131 . . . . . . . . . . . . . . . . . . . . . .. 16.09 3,91 2,95 60.62 10.17 6.26 ,4 Corn meal ratlon, Exp. 139-145 . . . . . . . . . . . . . . . . . . . . . .. 17.08 3.89 3.32 58.81 10.35 6.55 Feathers, Exp. 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,, 71 ,60 4_26 1,93 3.39 7.12 6.15 g Feathers, Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78.58 2.53 1.90 3.58 9.34 4.07 > é’ *The factor 6.25 is too high for the nitrogen of gelatine, z Table 10. Average composition, weights and calories per 100 grams of chickens Per cent Weight Calories Live Live Empty empty after per 100 Number of experiment and Number weight at weight at weight at weight of prepara- Protein Fat gm. name of ration averaged beginning end end live tion empty gm. gm. gm. weight gm. % % weight Experiment 125 Preliminary chicks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Calories per 100 gm... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration . . . . . . . . . . . . . . 7 73.7 490.2 469.6 95.7 451.1 22.86 7.48 199.4 Wheat bran ration . . . . . . . . . . .. 8 74.4 344.0 323.6 94.1 308.1 23.86 2.38 150.2 Experiment 139 and 145 Preliminary chicks . . . . . . . . . . . . . 6 . . . . . . . . . . 73.5 64.5 87.9 61.1 18.20 8.73 184. 5 Calories per 100 gm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experiment 145 Corn meal ration . . . . . . . . . . . .. 6 71.3 331.5 313.7 94.6 .304.4 23.57 5.21 182.1 Wheat bran ration . . . . . . . . . . .. 6 74.3 201.8 188.8 93.3 174.1 25.33 1.42 145.3 Experiment 131 Preliminary chicks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Calories per 100 gm... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration . . . . . . . . . . . . .. 7 54.4 794.5 766.8 96.5 746.0 23.19 7.83 204.5 Wheat bran ration . . . . . . . . . . .. 7 54.4 505.6 469.3 92.8 458.9 24.11 1.64 151.8 Experiment 45 - Preliminary chicks . . . . . . . . . . . . 5 . . . . . . . . . . 54.5 52 .3 96.1 50.4 18.36 6.86 164.3 Calories per 100 gm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Corn meal ration.............. 6 54.5 925.4 908.6 98.2 875.6 22.37 12.25 241.2 Wesson oil ration . . . . . . . . . . . . . 6 54.9 643.0 625.6 97.1 591.5 20.94 16.74 275.0 Casein ration . . . . . . . . . . . . . . . .. 6 55.3 991.4 977.8 98.6 942.0 25.07 5.10 189.6 Casein and Wesson oil ration. . 6 55.3 1088.1 1071.3 98.4 1019.3 23.13 6.97 196.1 Experiment 51 Preliminary chicks . . . . . . . . . . . . . 6 . . . . . . . . . . 46.2 43.8 94.8 39.7 17.38 7.15 165.2 Calories per 100 gm....... . . . . . . . . . . . . . . . . . . .. 156.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration . . . . . . . . . . . . . . 6 45.6 862.7 838.5 97.2. 809.7 22.56 12.96 248.8 Cottonseed oil ration . . . . . . . . . . 6 46.5 483.7 456.9 94.0 441.4 20.37 15.15 257.0 Casein ration . . . . . . . . . . . . . . . .. 6 46.5 991.1 959.0 96.7 915.1 25.01 5.75 195.3 Casein and cottonseed oil ration. 5 46.4 1025.4 981 .2 95.6 937.9 23.38 9.40 220.2 Experiment 58 Preliminary chicks . . . . . . . . . . . . . 6 . . . . . . . . . . 45.7 43.4 94.9 41.1 17.44 7.64 170.1 Calories per 100 gm....... . . . . . . . . . . . . . . . . . . .. 161.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration . . . . . . . . . . . . .. 6 46.7 1001.3 977.3 97.6 947.9 21.71 11.98 235.0 Oat hulls ration . . . . . . . . . . . . . .. 6 46.4 1004.2 976.2 97.2 939.8 24.52 6.42 198.8 Cottonseed meal ration . . . . . . . . 5 47.2 1003.1 966.3 96.2 924.7 24.18 4.61 179.9 Wheat bran ration . . . . . . . . . . .. 4 47.7 754.5 -730.3 .8 698.0 25.01 4.61 184.6 61 SNEDIOIHO eIO SLNEIWEIHIIIUEIH EIONVNELLNIVW Table 10. Average composition, weights and calories per 100 grams of chickenr-Continued Per cent Weight Calories Live Live Empty empty after per 100 Number of experiment and Number weight at weight at weight at weight of prepara- Protein Fat gm. name of ration averaged beginning end end liye tion empty gm. gm. gm. weight gm. % % weight Experiment 139 Corn meal ration . . . . . . . . . . . . .. 8 67.6 1233.3 1197.8 97.1 1161.8 25.16 12.60 248.5 Wheat bran ration . . . . . . . . . . . . 6 67.5 678.1 648.3 95.6 626.1 26.18 2.03 167.2 Experiment 14 ' Preliminary . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . 55.7 53.5 96.1 53.0 17.93 5.78 155.6 Calories per 100 gm . . . . . . . . . . . . . . . . . . . . . . . . . . . 149.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration . . . . . . . . . . . . .. 6 56.0 178.1 173.8 97.5 170.6 20.37 8. l0 191.0 Wesson oil ration . . . . . . . . . . . .. 5 56.7 135.7 130.8 96.4 128.9 19.11 14.16 240.6 Hydrogenated oil ration . . . . . .. 6 56.3 171.0 166.3 97.4 163.8 20.15 8.49 193.4 Hydrogenated oil ration . . . . . .. 6 56.7 157.1 152.2 96.8 149.9 18.53 13.25 228.7 Experiment 20 Preliminary chicks . . . . . . . . . . . . . 4 . . . . . . . . . . 51.5 47.8 92.8 49.5 16.78 7.25 162.8 Calories per 100 gm... . . .. . . . . . . . . . . . . . . . . . . .. 151.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Cottonseed oil ration . . . . . . . . . . 6 52.0 154.1 150.5 97.7 148.0 18.42 13.46 230.1 Corn oil ration... . . . . . . . . . . . .. 5 51.4 136.3 132.4 97.0 131.1 18.71 12.18 219.8 Peanut oil ration . . . . . . . . . . . . .. 6 52.3 139.3 135.0 96.9 133.4 18.79 12.22 220.6 Soybean oil ration . . . . . . . . . . . .. 6 51.6 139.1 134.7 96.9 133.5 18.60 12.38 221.0 Experiment 49 Preliminary chicks . . . . . . . . . . . . . 6 . . . . . . . . . . 51 .9 48.1 92.8 44.6 17.82 9.20 149.5 Calories per 100 gm....... . . . . . . . . . . . . . . . . . . .. 138.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration . . . . . . . . . . . . .. 6 51.8 194.3 187.7 96.6 180.3 19.95 10.83 214.2 Cottonseed oil ration . . . . . . . . .. 5 52.0 144.1 138.3 96.0 132.0 18.56 16.28 257.3 Casein ration . . . . . . . . . . . . . . . .. 6 51.7 197.8 192.3 97.2 185.1 21.30 4.42 165.6 Casein and cottonseed oil ration. 6 52.0 158.5 152.6 96.0 143.9 20.26 7.51 184.9 Experiment 50 Preliminary chicks . . . . . . . . . . . ..- 6 . . . . . . . . .. 50.6 46.9 92.6 44.0 18.41 5.41 154.8 Calories per 100 gm . . . . . . . . . . . . . . . . . . . . . . . . . .. 143.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration . . . . . . . . . . . . .. 6 51.3 218.3 211.6 96.9 202.2 21.37 5.99 176.9 Wesson oil ration . . . . . . . . . . . .. 6 51.6 146.3 140.0 95.6 133.6 19.38 12.32 224.9 Oat hull ration . . . . . . . . . . . . . .. 6 50.7 179.8 173.2 96.2 166.1 22.30 2.52 149.7 Oat hull and Wesson oil ration. . 6 50.6 142.2 135.2 94.8 126.3 19.92 9.75 203.9 Experiment 64 Preliminary chicks . . . . . . . . . . . . . 6 . . . . . . . . . . 57.6 54.0 93.7 54.7 18.08 6.50 163 1 Calories per 100 gm . . . . . . . . . . . . , . . . . . . . . . . . . .. 152.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Corn meal ration.............. 6 57.2 214.1 203.5 95.1 197.2 21.11 3.41 151.4 Gelatine ration . . . . . . . . . . . . . . .. 6 58.2 126.7 117.5 92.7 113.1 19.78 2.18 132.3 Egg albumen ration . . . . . . . . . .. 6 57.9 171.0 160.5 93.9 155.9 22.17 2.22 146.3 Blood albumen ration . . . . . . . .. 5 57.5 273.4 263.1 96.3 254.8 21.1 3.26 150.2 OZ NOLLVLS LNEINIHEIJXEI TVHIILTIIOIHDV SVXELL ‘S99 ‘ONI NLLEYTIIIH MAINTENANCE REQUIREMENTS OF CHICKENS 21 In the experiments lasting 12 to 18 weeks, the chickens moulted and the feathers were scattered around the room. The feathers collected averaged 17.4 gm. per chicken in Exp. 51, and 714 gm. each in Exp. 58. Composition of the feathers is given in Table 9. The energy content of the two samples of feathers was calculated to be 4. 5 and 4. 7 calories per gram and the total energy in the discarded feathers was approximately 78 and 35 calories. These quan- tities should be added to the energy gained by the chickens, and deducted from the energy used for maintenance, but such correction was not practical since the exact quantities shed by each group of chickens is not known. However, the total energy used for maintenance (Table 11) was over 4000 calories per chicken per period. The energy in the feathers was 1.8 and 0.9 per cent of 4000, so that the loss of the feathers would have very little effect upon the figures for maintenance requirements. Average data from the calculation of the energy used for maintenance are given in Table 11. As in previous work (6, 7, 8), the productive energy of the effective digestible nutrients of the corn meal ration was taken tp be 2.78 calories per gram. The maintenance requirements were calculated with use of the average weights per period. This has been shown to give more con- sistent results than the use of the average of the first and last weights and better in accord with the previous work of others than the use of the surface area (4). The productive energy of the feed eaten, less the energy gained by the chickens, gives the total productive energy used for maintenance, from which the main- tenance requirement per day per 100 grams were calculated. As shown in Table 11 the productive energy used for maintenance in the two experiments of 6 weeks each are 17.7 and 18.9 calories per 100 grams per day. These results are much higher than those secured in any of the experiments for 3 weeks previously reported (Tables 2, 3, 4, 5) except the 24.48 calories in Exp. 31 in Table 2. The quantities of productive energy used for maintenance in the four experiments for the periods of 12 weeks are close together, and their average of 13 . 1 calories per day per 100 grams is not far from the average of 13.7 calories found in 70 experiments for periods of 3 weeks mentioned on a preceding page. The energy used for maintenance in the single experiment for 18 weeks was 10.1 calories per day per 100 grams. This is appreciably lower than the 13.1 calories for the four 12 weeks experiments, and lower than all except two ex- periments (A-38 and A-41) of the previous experiments for 3lweeks in Table 3. This indicates that the chickens from 13 to 18 weeks old have lower main- tenance requirements per 100 grams than the younger chickens. This is in accordance with work reported by Mitchell and Haines (16), that the basal heat production of chickens weighing 2705 grams was 63 calories per kilogram of body weight, while for those weighing 1321 grams it was 81 calories per kilogram. If the maintenance requirements of the chickens up to the age of 12 weeks in the 18 weeks experiment were considered to be 13.7 calories per 100 grams per day, the maintenance requirement calculated as shown in Table 12 for the period of from 12 to 18 weeks would be 7 .2 calories per day per 100 grams. With a ration containing 1.9 calories of productive energy per gram, approx- Table 11. Average data and calculation of maintenance requirements of chickens fed on the standard corn meal ration ZZ For maintenance Percentage of P. E. Period of Number _ _ _ Prod. Prod. Total Prod. Prod. Experiment of ration experi- of Average Inltlal Final Gain energy of Ration energy of prod. energy per energy per number found in ment chickens weight by energy energy of energy ration eaten feed energy period per day per gain weeks periods content content cal. eaten 100 gm. 100 gm. gm. cal. cal. cal. per gm. gm. cal. cal. cal. cal. 31 6 7 253.5 111.3 938.6 827.3 1.92 1407.1 2697.4 1870.1 742.3 17.7 22 6 6 196.7 115.7 570.9 455.2 1.84 1103.5 2026.0 1570.8 795.3 18.9 26 12 ' 7 399.4 82.2 1572.9 1490.8 1.92 3027.7 5804.1 4313.3 1084.5 12.8 34 12 6 382.3 86.1 2185.5 2099.5 1.95 3128.2 6093.8 3994.3 1043.8 12.4 33 12 6 348.6 71.4 2082.7 2011.3 1.92 3151.7 6063.9 4052.7 1164 4 13.9 34 12 6 366.1 75.3 2292 2 2216.8 1.96 3317.3 6498.6 4281.8 1170.2 13.9 25 18 8 668.8 109.7 2956.2 2846.5 1.84 6168.1 11324.5 8477.9 1269.1 10.1 48 3 6 110.7 83.7 332.4 248.7 1.98 262.4 518.6 269.9 247.2 11.8 51 3 6 104.6 78.5 353.1 274.6 2.32 231.3 536.7 262.1 252.7 12.0 47 3 6 127.4 71.8 405.1 333.3 1.94 380.7 707.1 403.8 318.3 15.2 44 3 6 136.7 73.6 374.8 301.2 1.88 365.9 587 5 386.3 282.6 13.5 40 3 6 128.1 87.4 309.1 221.7 1.84 308.3 558.0 336.3 263.0 12.5 NOLLV-LS LNEINIHEJXEI "IVHHJFIIIOIHOV SVXELL ‘£99 'ONI NLLTITIIH MAINTENANCE REQUIREMENTS OF CHICKENS 23 Table 12. Energy for maintenance for the period of from 12 to 18 weeks Average weight by periods to 12 weeks, grams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445 Energy used for maintenance, 18 weeks (A) calories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8478 Energy used for maintenance, 12 weeks (B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5121 .137 X 445 X 84 = (B) Energy used for maintenance, 42 days, 12 to 18 weeks (A —B =C) . . . . . . . . . . . . . . . . . . . 3354 Average weight by periods 12 to 18 weeks, grams . . . . . . . . . . . . . . . . . . . . . . . . . . 1113 Energy used for maintenance, calories per day per 100 gram =100C + (1113 X42) = D... 7.18 imately 37 grams of the ration per day and kilogram would be required for maintenance of the older chickens. This is not far from the 42 grams of feed per day per kilogram calculated from the results reported by Titus (18) for laying White Leghorn pullets, or the 46.5 gm. ration per day per kilogram calculated from the work of Brody, Fork, and Kempster (2) for laying hens. Laying hens could be expected t0 have somewhat greater maintenance re- quirements than growing chickens. Additional experiments are needed with chickens of from 12 to 18 weeks old or older, since a single experiment cannot be considered to give the exact value. In the five experiments of 3 weeks duration here reported (Table 11), the maintenance requirements of the young chickens ranged from 11.8 to 15.2 calories per day per 100 grams, with an average of 13.0. The maintenance requirements were lower than usual for four of the 6 experiments. Productive Energy Values of the Feeds with Chickens to the Age of 7 t0 19 Weeks The experiments included comparisons of the energy values of the experi- mental feeds “rith that of corn meal, as was done in previous work (6, 7). If part of the metabolizable energy not utilized as productive energy can be used for maintenance, there might be differences between productive values secured from chickens fed for 6 to 18 weeks, which might not be apparent in the shorter feeding periods of 3 weeks with smaller and younger chickens. r‘ < -' '“"”_‘""'"""U""P'""_“P"1TY'§”V"WIVILV~v.-<~q-v<-yv\'vy< -..,- -.,- _.. w _ m. That portion of the productive energy of the ration used for maintenance averaged 52 7O of the productive energy fed in the experiments for 3 weeks, 73% in the experiments for 6 weeks, 68% in the experiments for 12 weeks, and 75% in the experiment for 18 weeks. If the heat of utilization could be used . for maintenance purposes and thereby save productive energy, the productive energy of the ration should be appreciably greater in the experiments for 6, 12 or 18 weeks than in the experiments for 3 weeks. Apparently such was ‘i’ not the case. The average maintenance requirements given in Table 11 were used to calculate the productive energy of the rations fed in the same experiments containing the feeds which were compared with corn meal, with the results given in Table 13. The method of procedure in each case is indicated by the Table 13. Data and calculation for average productive energy of rations and etfective digestible nutrients Efiect _ No. Ayerage Initial Final Gain of Ration Used for For gain Prod. digest. Experiment number and aver- weight by energy energy energy eaten main- and energy of nut. of name of ration aged periods content content tenance main- ration ration gm. cal. cal. cal. gm. cal. tenance cal. per cal. per gm. 100 gm. Experiment 125. 6 weeks Wheat bran . . . . . . . . . . .. 8 182.1 112.3 485.9 373.5 1401.2 1251.4 1724.9 1.231 49.2 Experiment 145. 6 weeks . Wheat bran . . . . . . . . . . .. 6 139.7 120.6 273.6 153.0 974.9 1110.5 1263.5 1.174 41.8 Experiment 131. 12 weeks Wheatbran............. 7 277.3 82.2 713.4 631.2 3095.8 3007.5 3638.7 1.173 49.2 Experiment 45._ 12 weeks Cottonseed oil . . . . . . . . . . 6 289.6 86.7 1799.7 1713.0 2312.1 3023.7 4736.7 1.998 88.9 Casein . . . . . . . . . . . . . . . 6 431. 5 87.4 1860.2 1772.8 3061.8 4654.9 6427.6 2.091 69.3 Casein and cottonseed oil 6 426.6 87.4 2092.0 2004.6 2537.6 4453.9 6458.5 2.510 91.8 Experiment 5l._ 12 weeks Cottonseed oil . . . . . . . . .. 6 214.6 72.8 1190.6 1117.8 1668.0 2498.6 3616.4 2.170 90.8 Casein . . . . . . . . . . . . . . . 6 425.9 72.9 1865.9 1793.0 3015.7 4959 .2 6752.2 2.257 68.1 Casein and cottonseed oil 5 383.3 72.7 2150.8 2078.1 2404.7 4463.6 6541.7 2.726 91.5 Experiment 58. 12 weeks Oat hulls . . . . . . . . . . . . . .. 6 389.3 70.9 1945.2 1870.4 4689.6 4542.3 6412.7 1.364 47.1 Cottonseed meal . . . . . . . . 5 394.9 76.2 1737.6 1661.4 3989.8 4619.9 6281.2 1.575 51.4 Wheat bran . . . . . . . . . . . . 4 320.1 77.1 1347.9 1270.9 3994.7 3746.7 5017.5 1.251 45.3 Experiment 139. 18 weeks Wheat bran . . . . . . . . . . . . 6 398.5 109.5 1086.8 977.3 5663.3 5061.1 6038.4 1.064 41.8 Experiment 14. 3 weeks Cottonseed oil . . . . . . . . . . 5 97.4 84.7 321 .0 236.3 203.9 240.7 477.0 2.372 88.2 Hydrogenated oil........ 6 110.0 84.1 321.8 237.7 288.9 271.6 509.3 1.767 67.4 Hydmgeflated Oil - - - - - - - . 6 106.1 84.8 347.7 263 .0 225. 7 262.2 525.1 2.342 89. 5 Experiment 20. 3 weeks Corn oil . . . . . . . . . . . . . .. 5 97.7 77.5 294.3 216.7 210.0 247.3 464.0 2.192 81.0 Peanut oil . . . . . . . . . . . . .. 6 97.1 79.0 299.8 220.9 206.4 245.8 466.7 2.260 81.0 Soybean oil . . . . . . . . . . . . . 6 98.5 77.9 298.4 220. 5 201.0 249.2 469.7 2.350 84.6 Experiment 49. 3 weeks Cottonseed oil . . . . . . . . . . 5 109.6 72.2 360.2 288.0 288.0 348.4 636.4 2.190 87.5 Casein . . . . . . . . . . . . . . . .. 6 128.7 71.7 318.5 246.9 308.0 409.1 656.0 2.128 67.3 Casein and cottonseed oil. 6 108.4 72.2 283.3 211.2 205 .2 344 .8 556.0 2.737 87.1 Experiment 50. 3 weeks Cottonseed oil . . . . . . . . .. 6 106.7 73.9 314.9 241.0 238.8 301.9 542.9 2.287 90.2 Oat hulls . . . . . . . . . . . . . .. 6 122.4 72.7 260.6 187.8 416.0 346.3 534.1 1.279 45.9 Oat hulls and cottonseed oil . . . . . . . . . . . . . . . . . .. 6 103.7 72.5 280.1 207.6 270.8 293.4 501.0 1.825 66.4 Experiment 64. 3 weeks Gelatine . . . . . . . . . . . . . .. 6 86.2 88. 8 156.8 67.9 204.9 226.7 294. 6 1.465 65.4 E galbunien . . . . . . . . . .. 6 115.4 88.5 235.1 146.7 313.9 303.5 450.2 1.434 56.1 Bood albumen.......... 5 159.7 87.9 394.5 306.6 398.4 420.1 726.7 1.829 63.4 73 NOLLVLS LNEIWIHEIJXEI "IVHIIJJIIIOIHDV SVXELL ‘Q99 ‘ON NLLEITIIIH Table 14. Productive energy in terms of feed, eflective organic constituents, eflective digestible nutrients, and metabolizable energy Experimental feed Productive energy of experimental feed Rank with Metab- Efiective Efiective efiective In ‘per- Length Effective Effective olizable Total organic digestible digestible centage of of period, Percent organic digestible energy feed const1t- nutrients nutrients metab- weeks of constit- nutrients Cal. per Cal. per uents Cal. per of corn olizable ration uents % 100 gm. 100 gm. Cal. per 100 gm. meal as energy % 100 gm. 100 Name of Feed Casein, Exp. 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 30 87.3 77.8 327 289 331 372 124 89 Casein (with oil), Exp. 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 30 87.3 89.9 378 412 472 '458 153 110 Casein, Exp. 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 30 87.9 76.0 319 351 399 462 154 110 Casein (with oil), Exp. 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 30 87.9 81.9 344 423 481 516 172 123 Casein (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369 421 452 151 108 Casein (average), 3 weeks . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 224 256 317 105 76 Cottonseed oil, Exp. 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 20 225.0 174.5 733 266 264 175 58 36 Cottonseed oil (with casein), Exp. 45 . . . . . . . . . . . . . . . . . . . . 12 20 225.0 192.8 809 451 200 234 78 56 Cottonseed oil, Exp. 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 20 225 . 0 188.0 789 363 161 193 64 46 Cottonseed oil (with casein), Exp. 45 . . . . . . . . . . . . . . . . . . . . . 12 20 225.0 196.9 827 474 211 241 80 57 Cottonseed oil (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . - ~ . . . . . . . . . . 467 208 237 79 57 Cottonseed meal, Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 50 83.0 41.8 176 163 197 390 130 93 Cottonseed meal (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 152 280 93 67 Oat hulls, Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 50 56.7 1.9 8 45 . . . . . . . . . . . . . . . . . . . . 100 . . . . . . . . . . Oat hulls (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wheat bran, Exp. 125 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18 50 80.3 40.1 168 102 127 254 85 61 Wheat bran, Exp. 145 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 5O 80.3 31.1 131 107 133 343 114 82 Wheat bran, Exp. 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 50 75.3 29.6 124 98 131 331 110 79 Wheat bran, Exp. 131 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 50 80.3 40.1 168 90 112 205 75 54 Wheat bran, Exp. 139 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 50 80.3 31.1 131 85 106 272 91 65 Wheat bran (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6, 12, 18 . . . . . . . . . . . . . . . . . . . - . . . . . . . . - - . . . . . . . . .. 96 121 280 95 68 Wheat bran (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 100 125 91 65 e QZ SNGIHOIHO .10 SLNEIWEIHIIIDEHI EIONVNEILNIVW ; Table 15. Productive energy in terms of feed, effective organic confitituents, effective digestible nutrients, and metabolizable energy. 3 wee s Productive energy _ Rank of Effective Effective Metab- Effective effective Percent organic digestible olizable Total organic Effective digestible In per- of constit- nutrients energy feed constit- digestible nutrients centage of ration uents % Cal. per Cal. per uents nutrients with those metab- 0 100 gm. 100 gm Cal. per Cal. per of corn olizable 100 gm. 100 gm. meal as energy 100 Name and laboratory number of feed Corn meal, Exp. 14 . . . . . . . . . . . . . . . . . . . . . . . . . . 90.9 79.9 336 240 264 300 100 71 Cottonseed oil . . . . . . . . . . . . . . . . . . . . 15 225.0 192.0 806 499 222 260 87 62 Hydrogenated oil, B . . . . . . . . . . . . . .. 15 225.0 53.7 226 95 42 177 59 42 Hydrogenated oil, A . . . . . . . . . . . . . .. 15 225.0 200.9 844 479 213 238 79 57 Cottonseed oil, Exp. 2O . . . . . . . . . . . . 15 225.0 215.1 903 475 211 221 100 53 Corn oil . . . . . . . . . . . . . . . . . . . . . . . . . . 15 225.0 199 .1 836 390 173 196 89 47 Peanut oil . . . . . . . . . . . . . . . . . . . . . . . . 15 225.0 198.7 835 435 193 219 99 52 Soybean oil . . . . . . . . . . . . . . . . . . . . . . . 15 225.0 222.6 935 495 220 222 100 53 Corn meal, Exp. 49 . . . . . . . . . . . . . .. 5O 91.1 80.2 336 241 265 300 100 72 Casein . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 87.9 72.3 304 304 346 422 141 101 Casein (oil) . . . . . . . . . . . . . . . . . . . . . .. 30 87.9 78.6 330 423 481 538 179 128 Cottonseed oil . . . . . . . . . . . . . . . . . . . . 20 225.0 169.7 712 368 164 217 72 52 Corn meal, Exp. 50 . . . . . . . . . . . . . .. 5O 88.4 79.2 333 238 269 300 100 71 Cottonseed oil . . . . . . . . . . . . . . . . . . . . 2O 225.0 192.2 807 442 196 230 77 55 Oat hulls . . . . . . . . . . . . . . . . . . . . . . . . . 30 56.7 6.9 29 38 67 55 100 100 Cottonseed oil (with oat hulls) . . . . . . 20 225.0, _ 181.7 763 510 227 281 90 67 Corn meal, Exp. 64 . . . . . . . . . . . . . . . 5O 87.9 73.3 308 220 250 300 100 72 Gelatine . . . . . . . . . . . . . . . . . . . . . . . . . . 30 82.6 70.0 294 98 119 140 47 33 Egg albumen . . . . . . . . . . . . . . . . . . . . . 30 85.9 39.0 164 83 97 213 71 51 Blood albumen . . . . . . . . . . . . . . . . . . . . 30 76.4 63.0 265 217 284 344 115 82 Cottonseed oil average, Exp. 14, 49, 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 59 Casein average, Exp. 49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 115 93 NOLLVLS LNEIWIHEXJXH ‘IVHHI/IIIOIHDV SVXELL ‘Q99 'ON NLLEYYIIIH MAINTENANCE REQUIREMENTS OF CHICKENS 27 headings of Table 13. The productive energy used for maintenance is cal- culated by multiplying the average weight in grams by periods by the calories used to maintain one gram of chicken as found by the use of the corn meal ration in the same experiment. The sum of the calories in the gain and the calories used for maintenance, divided by the grams of feed eaten, gives the calories of productive energy of one gram of the ration, as shown in Table 13. The calculations were made for each chicken separately and then averaged. The productive energy values of the feeds were calculated from the pro- ductive energy of the rations by the procedures already described in detail (6, 7). The difference between the productive energy of one gram of the corn meal ration and one gram of the ration containing the feed to be compared gives the effect of the substitution. This difference added to the productive energy of the quantity of corn meal substituted gives the productive energy of the quantity of the feed which replaced the corn meal. The effective digest- ible nutrients of the feeds tested were calculated in a similar way from the digestion experiments and the composition of the feeds and rations. The productive energy values of the various feeds as calculated for the periods of 6, 12, and 18 weeks are given in Table 14. For comparison of the longer experiments with those for three weeks, the average data for experi- ments on the same feeds already published (6, 7) are included. Since there are differences in digestibility, comparisons are best made of the values of the different feeds by means of the productive energy per unit of effective digestible constituents and in percentages of metabolizable energy. Oat hulls had a higher value in the one 12 weeks experiment than the average of the experiment for 3 weeks previously reported, but the total productive energy value is so low that slight differences between the results secured with the entire rations would produce those differences. The digestibility of oat hulls is so low and variable that comparative energy values are not significant. The productive energy value of the casein in three of the four experiments for 12 weeks is greater than the average value secured in the experiments for periods of 3 weeks previously reported. The relative productive energy of 100 grams of the effective digestible nutrients of the casein compared with that of corn as 100, averages 151, while the average for the 3 weeks experiments previously reported is 105. However, the rations fed in experiment 49, with younger chicks for 3 weeks, were the same as those fed in experiment 48 re- ported in Table 15 and the relative value of the casein is 149 and 179, which is likewise high. This indicates that the greater value of casein found in this work compared with previous work is not due to the age of the chickens but to other factors. In calculating the productive energy values, it is necessary to assume that the productive energy used for maintenance per 100 grams of live weight is the same for the experimental rations as for the standard corn meal ration fed in the same experiments. If there are differences in the energy used for maintenance by the different groups compared in the same experiment, the differences would cause differences in the values secured for the productive energy. As shown on a preceding page, the higher protein content of the casein ration may have caused lower maintenance requirements than those due to the corn meal ration. This may be the cause of the high value for productive BULLETIN NO. 665, TEXAS AGRICULTURAL EXPERIMENT STATION 28 energy secured in those experiments. The productive energy of the casein is greater than its metabolizable energy in three of the experiments in Table 14 and one in Table 15. Since the metabolizable energy is the entire quantity of energ-y which the animal can secure from the food, the productive energy should not exceed it, so that this evidence indicates that the values for the productive energy of the casein are too high in these experiments. The relative value of the efiective digestible nutrients of cottonseed oil, Table 14, averaged 61 (with corn meal as 100) in the two experiments of 12 weeks, compared with 79 as the average of the 3 weeks experiments previously reported (7) for cottonseed oil. In the other two of these experiments for 12 weeks in which casein was fed as 30% of the ration, the relative values for cottonseed oil were 78 and 80, practically the same as the average of 79 for the previous 3 weeks experiments. It would appear that the low value for cotton- seed oil secured in the two experiments was probably due to differences in maintenance requirements between the experimental ration and the standard corn meal ration, and not to less efficient use of the oil by the older chickens than by the younger ones. Only one experiment was made with cottonseed meal in the 12 weeks experi- ments. As was the case with the casein, the relative productive energy of the cottonseed meal was higher than the value secured for the younger chickens in the 3 weeks experiment. With the wheat bran, two experiments of 6 weeks duration were made, two were made for 12 weeks, and one for 18 weeks. The average relative value of the eflective digestible nutrients for the five experiments is 95, compared with corn meal as 100, with an average of 91 for the 3 weeks experiments previously reported. These averages are practically the same. The relative value was 91 in the 18 weeks experiment, which is the same as the average value secured in the 3 weeks experiment. The average for the two 12 weeks experiments is 98 and for the two 6 weeks experiments is 100. These are a little higher relative values than for the 3 weeks experiment, but the other work reported indicates that these values are too high. The conclusion reached is that the chickens 6 to 18 weeks old utilize the metabolizable energy for production of fat and flesh as efiiciently as the younger chickens less than 4 weeks old. These experiments attest the validity of the method of experiment used in comparing the productive energy values of various feeds with that of corn meal, since widely differing periods of time give nearly the same results. The work on chickens, together with that done on rats (8), indicates that the value of productive energy used for maintenance per day per 100 grams is usually the same with the corn meal ration as with rations in which other feeds are substituted for corn meal in the same experiment. Productive Energy Experiments to the Age of About 4 Weeks A summary of the results of the experiments of 3 weeks duration here re- ported is in Table 15. Two samples of hydrogenated cottonseed oil were used in experiment 14, one of which (A) was of the consistency used in human foods, while the other (B) was harder than is used for human foods unmixed with MAINTENANCE REQUIREMENTS OF CHICKENS 29 other oils 0r fats. Sample A had an iodine value of 65 and B, of 10. Sample A was slightly more digestible (11) than the cottonseed oil with which it was compared, and had about 10 per cent lower value in productive energy than the oil with which it was compared in the same experiment but its productive energy averaged about the same as the average of other experiments with cottonseed oil (7). The hard sample of hydrogenated oil had a low digesti- bility, and the oil digested from it had about 70 per cent of the productive energy of sample A. Cottonseed oil, peanut oil and soybean oil had practically equal productive energy values in experiment 20. Corn oil had about 10% lower productive energy per unit of digested oil than the other oils used in the same experiment and the fat had slower digestibility, but one experiment is not sufficient to show that its value is lower than that of the others. The productive energy of gelatine was low in experiment 64. Egg albumen had a higher value than gelatine, while blood albumen had a higher value than corn meal. Productive Energy Where Maintenance Requirements of Older Chickens are Calculated on, the Surface Area Basis Compared with Calculations on the Weight Basis The method used to measure the productive energy of the corn meal ration was to feed one group of chickens on limited quantities of the ration, and another group on unlimited quantities of the same ration, and then calculate the productive energy of the ration, and productive energy used for maintenance from the data by an algebraic method from the equations given on a previous page. In order to make this calculation, it is necessary to assume that the calories of productive energy used for maintenance vary either in proportion to the weights or in proportion to the surface areas of the chickens. The results were calculated for both assumptions and the weight basis was found to give the more reasonable results (4). The results calculated on the weight basis were more consistent and better in accord with other published work than those calculated on the surface basis, and the weight basis has accordingly been used on the work subsequently reported. The results secured have indicated that this procedure is correct. The work was done with chickens up to a maximum age of 42 days except one experiment, in which older chickens. were used, and this experiment indicated that the result might possibly be different with older chickens (4). It is obvious that if there are only small differences between the final weight of the animals grown with the corn meal ration and those grown at the same time with another ration, in which the corn meal was replaced by the feed to be tested, it will make little difference whether the weight basis or the sur- face area basis is used. If the final weights differ, however, the two methods of calculation will give different results. The greatest differences in weights of the chickens compared in the work here discussed, were in experiment 139 which had been carried on for 18 weeks. The weights by periods were appre- ciably greater for the chickens which had received the standard corn meal 30 BULLETIN NO. 665, TEXAS AGRICULTURAL EXPERIMENT STATION ration than for those which received the ration in which corn meal was re- placed by wheat bran. This experiment was selected to again compare the two methods 0f calculating the maintenance requirements. The surface area was calculated for each weight of each chicken as was done in the work previously reported, by the formula of Southgate (4) S =9 . 3 W's‘; in which S is the surface and W the weight. The surface by periods was cal- culated from this data. The amount of calories used for maintenance was calculated for the corn meal ration both by weight and by surface and the productive energy was then calculated for the wheat bran ration. The average data are summarized in Table 16. From Table 16, it is seen that the average surface area and the average weight of the chickens on the corn meal ration, as averaged by periods, are of equal magnitude. This results in almost the same number of calories of energy per unit of area or of weight. The surface areas of the smaller chickens, on the wheat bran ration, are proportionately larger than the weights. This results in an apparent use of 957 more calories of energy for maintenance per chicken by the surface area basis than by the weight basis. The result is that on the surface area basis, the wheat bran ration has a productive energy of 1.234 calories per gram, compared with 1.064 calories on the basis of the weight. When the productive energy of the wheat bran is calculated on the surface basis, its digestible nutrients have a value of 127 while on the weight basis they have a value of 91, compared with those of corn meal as 100. From our knowledge of the chemical composition of wheat bran it is unreasonable to assume that its digestible nutrients have higher values than those of corn meal. The value on a weight basis is reasonable and in accord with the values previously published (7). The value on the surface area basis is unreasonable because it is too high. Table 16. Comparison of surface area basis with weight basis. Exp. l39—18 weeks Weight Surface basis basis Corn meal ration. Average weight in grams or surface in sq. cm. by periods (W) . . . . . . . . 669 682 Productive energy of feed eaten, calories (E) . . . . . . . . . . . . . . . . . . . . . . . 11325 11325 Energy gained by chickens, calories (G) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2847 2847 Total productive energy used by chickens (E —G =N) . . . . . . . . . . . . . . . 8478 8478 Productive energy used for maintenance per day pcr 100 gm. or cm. 100N+DW=M (D is 126 days) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10.1 9.8 Wheat bran ration. Average weight or surface by periods, (V) wheat bran ration . . . . . . . . . 399 485 Energy gained by chickens, calories (H) . . . . . . . . . . . . . . . . . . . . . . . . . . . 977 977 Energy used for maintenance, calories (MVD +100 =K) . . . . . . . . . . . . . 5061 6018 Productive energy of feed eaten (H +K =F) . . . . . . . . . . . . . . . . . . . . . . . . (1038 6995 Grams of ration eaten (R) . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . 5663 5663 Productive energy of wheat bran ration, calories per gram F +R . . . . . . 1 .064 1 .234 Productive energy of wheat bran, calories per 100 grams l . . . . . . . . . . . . 85 119 Productive energy per 100 grams of effective digestible nutrients of wheat bran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272 381 Productive energy of effective digestible nutrients of wheat bran compared with that of corn meal as 100 . . . . . . . . . . . . . . . . . . . . . . . 91 127 Prodkuctive energy of 100 calories of metabolizable energy in wheat 6_ 9O ran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . o MAINTENANCE REQUIREMENTS OF CHICKENS 31 For three of the other four experiments with wheat bran (Table 11) inspection shows that calculation by the surface basis instead of the weight basis would give too high results. It would appear from the work here presented that for chickens up t0 18 weeks old, the average weight by periods is a better basis than the surface area, for calculating the energy used for maintenance when the data is to be used to calculate the productive energy of the food. Effect of Variations in Energy Used for Maintenance in the Same Experiment Upon the Measurements of Productive Energy In order to calculate the productive energy of the feeds and rations, it is necessary to assume that the productive energy used for maintenance is the same per day per 100 grams live weight with the groups receiving the test feeds as with the group receiving the corn meal ration at the same time and under the same conditions. Differences in the quantities of productive energy used for maintenance between the two groups being compared would result in in- correct results for the productive energy calculated. As stated on a preceding page there are differences (4) in the quantities of energy used for maintenance between individual chickens fed on the same feed at the same time. Itis too much to expect that these differences will always be averaged out for each group in all experiments. In some experiments, the energy used in maintenance will not be the same in the groups compared and incorrect values for productive energy will occur. These errors can be eliminated only by repetition of the work on a sufficient number of times. Differences in productive energy used for maintenance may also occur if there are wide differences in protein content. Differences in maintenance requirements may occur between chickens fed at different times, for reasons which remain to be ascertained. Since variations in energy used for maintenance may occur in the same experiment, the differences in productive energy already reported in some cases may be due chiefly to differences in energy used for maintenance of the animals rather than differences in productive energy of the feeds. It seems more logical to conclude that variations in maintenance requirements between the groups of chickens compared are more likely to occur than differences in the productive energy secured by the animal from the same chemical compounds. The unreasonably high values for casein in the work just reported (Tables 14, 15)’ may be due to differences in energy used for maintenance rather than to differences in the productive value of casein. To test this possibility the energy used for maintenance was calculated on the assumption that the digest- ible constituents of casein per unit had the same productive energy as those , of corn meal. The results are given in Table 17. Table 17 shows that com- paratively small differences in the energy used for maintenance between the groups compared would account for the high productive value of the casein. Several experiments were selected in which too high values were obtained“ for the productive energy of the feed. Table 18 shows the results secured When, on the one hand, the maintenance requirements are assumed to remain constant per day per 100 grams, and the productive energy is calculated; and 32 BULLETIN NO. 665, TEXAS AGRICULTURAL EXPERIMENT STATION Table 17. Maintenance requirements when productive energy is constant. Exp. 51 Cal /day /100 gm. Corn meal ration. . . . ._ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13.9 Corn meal and casein ration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 .2 Difference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 Assumed productive energy of casein in per cent of metabolizable energy . . . . . . . . . . 72 Found productive energy of casein assuming that maintenance requirements are constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- . . . . . . . . . . . . . . . . . 110 Table 18. Maintenance requirements calculated on the assumption that productive energy is constant, compared with productive energy calculated on the assumption that main- tenance requirements are constant and equivalent to those of the corn meal ration _ Relative Maintenance productive requirements energy of Protein digestible in ration Per day nutrients, % per 100_ gm. Corn meal corn meal calories as 100 as 100 Exp. 37. Corn meal ration . . . . . . . . . . . . . . .. 16.8 16.99 100 100 Linsead oil meal . . . . . . . . . . . . . . . . . . . . .. 30.4 17.27 102 105 Soy bean oil meal . . . . . . . . . . . . . . . . . . . . . . 34.5 13.41 79 124 Fish meal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.8 15.02 88 125 Exp. 38. Corn meal ration . . . . . . . . . . . . . . .. 16.6 16.36 100‘ 100 Corn gluten feed . . . . . . . . . . . . . . . . . . . . . . . 23.5 14.77 90 131 Corn gluten meal . . . . . . . . . . . . . . . . . . . .. 33.3 13.54 83 136 Peanut meal . . . . . . . . . . . . . . . . . . . . . . . . . . 31 .3 14 34 88 124 Exp. 57. Corn meal ration . . . . . . . . . . . . . . .. 16.5 16.84 100 100 Cottonseed flour . . . . . . . . . . . . . . . . . . . . . . 38.8 18.21 108 93 Linseed oil meal. . . ., . . . . . . . . . . . . . . .. 29.7 14.72 87 146 Exp. 59. Corn meal ration . . . . . . . . . . . . . . .. 16.2 18.32 100 100 Sweet potatoes . . . . . . . . . . . . . . . . . . . . . . . . 13.3 18.62 102 93 Dried beef . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.0 12.96 71 166 Liver meal . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.9 12.41 68 137 when, on the other hand, the productive energy is assumed to be equal for equal quantities of digestible nutrients, and the maintenance requirements are calculated. An examination of the data shows that the high values secured for productive energy may really be due to differences in the energy used for maintenance in the groups compared, although they were assumed to be equal for the purpose of calculating the productive energy. The differences for maintenance shown in the tables are not unreasonable, and even greater differ- ences have been found to occur between different groups of animals fed at different times. Some of the differences in energy used for maintenance are not wider than have been found between individual chickens- fed on the same feed at the same time. ACKNOWLEDGMENT Experiments 125-129-135-139 were partly made by Major J. R. Couch, who discontinued the work when he entered the army. Mr. E. C. Carlyle and other members of the staff did other work and their services are gratefully acknowledged. ‘ 1i MAINTENANCE REQUIREMENTS OF CHICKENS 33 SUMMARY The maintenance requirements of chickens from about 7 to 28 days old in 70 experiments ranges from 9.4 to 20.5 calories of productive energy per day per 100 grams with an average of 13.6. Expressed in terms of a ration having a productive energy of 1.9 calories per gram, the maintenance requirements are ranged from 5.0 to 10 .8 grams per day per 100 grams of live weight with an average of 7.2 grams. Maintenance requirements for individual chickens fed the same ration under approximately the same conditions at the same time varied to a considerable extent, the standard deviation averaging 1.01 for 6 groups of chickens requiring an average of 13.7 calories of productive energy per day per 100 grams of live weight. Differences in weight and in sex had no effect on maintenance requirement of the young chickens. Chickens receiving rations high in protein had much lower maintenance requirements than those receiving rations low in protein. With a ration which averaged 31.0 per cent protein, the average maintenance requirements were 12.4 calories of productive energy per day per 100 grams with a standard deviation of 0.8 while with rations averaging 16.2 per cent protein, the maintenance requirements were 15.8 calories per day per 100 grams with a standard‘ deviation of 1.7. The effect of protein on growing chickens is contrary to the idea that protein has a specific dynamic action which increases the heat eliminated by animals. While there is some relation between the protein content of the ration and the maintenance requirements, other factors as yet unknown caused wide differences. The maintenance requirements ranged from 9 . 4 to 17. 7 calories of productive energy per day per 100 grams live weight with chickens fed rations containing 18 to 24 per cent protein. Chickens up to the age of 12 weeks had approximately the same maintenance requirement per day per 100 grams as the younger chicks. In one experiment, chickens from 12 to 18 weeks required only 7.12 calories of productive energy per day per 100 grams, which is much lower than the average of 12.6 calories for the younger chickens. Chickens 6 to 18 weeks old utilize the metabolizable energy of food for pro- duction of fat and flesh as efficiently as younger chickens. Hydrogenated cottonseed oil with an iodine number of 65 had about the same digestibility and productive energy value as cottonseed oil. Hydro- genated oil with an iodine value of 10 had a low digestibility and the digested portion had about 70 per cent of the productive energy of cottonseed oil. When the maintenance requirements were calculated on the surface area basis in an experiment lasting 18 weeks, the productive energy calculated for wheat bran was unreasonably high. The weight basis is more suitable for calculating maintenance requirements for the older chickens, just as it was found to be for young ones in previous work. In calculating the productive energy of rations or feeds, it is necessary to assume that the productive energy required for maintenance per day per 100 grams averages the same for animals on the experimental rations as on the 9 34 BULLETIN NO. 665, TEXAS AGRICULTURAL EXPERIMENT STATION standard corn meal ration with which they are compared. 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