E-133-6M-L180 TEXAS AGRICULTURAL EXPERIMENT STATIIIN A. B. CONNER. DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 514 SEPTEMBER, 1935 DIVISION OF POULTRY HUSBANDRY and DIVISION OF CHEMISTRY The Vitamin A Requirements of Hens for Egg Production i I??? £51. 54? ‘I’ 7: ‘ 1:1"??? (‘nflzinw n! Twyié? AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President sea-a.- Administration : A. B. Conner, M. S., Director R. E. Karper, M. S., Vice Director Clarice Mixson, B. A., Secretary M. P. Holleman, Chief Clerk D. R. McDonald, Asst. Chief Clerk Chester Higgs, Executive Assistant Howard Berry, B. S., Technical Asst. Chemistry: G. S. Fraps, Ph. D., Chief; State Chemist S. E. Asbury, M. S., Chemist J. F. Fudge, Ph. D., Chemist E. C. Carlyle, M. S., Asst. Chemist T. L. Ogier, B. S., Asst. Chemist A. J. Sterges, M. S., Asst. Chemist Ray Treichler, M. S., Asst. Chemist W. H. Walker, Asst. Chemist Velma Graham, Asst. Chemist Jeanne F. DeMottier, Asst. Chemist W. H. Garman, M. S., Asst Chemist A. R. Kemmerer, Ph. D., Asst. Chemist A. W. Waldo, Ph. D., Asst. Chemist F. J. McClure, Ph.D., Asst. Chemist Horticulture: S. H. Yarnell, Sc. D., Chief Range Animal Husbandry: J. M. Jones, A. M. Chief B. L. Warwick, Ph. D., Breeding Investiga. S. P. Davis, Wool and Mohair Specialist J. H. Jones, B. S., Animal Husbandman .n..n\r 1 Veterinary Science : nv---_ Q - ‘M. Francis, D. V. M., Chief H. Schmidt, D. V. M., Veterinarian "F. P. Mathews, D. V. M., M. S., Veterinarian Plant Pathology and Physiology: J. J. Taubenhaus, Ph. D., Chief W. N. Ezekiel, Ph. D., Plant. Pathologist L. B. Loring, M. S., Asst. Plant Pathologist G. E. Altstatt, M. S., Asst. Plant Pathologist “Glenn Boyd, B. S., Asst. Plant Pathologist Farm and Ranch Economics: L. P. Gabbard, M. S., Chief W. E. Paulson, Ph. D., Marketing C. A. Bonnen, M. S., Farm Management I“W. R. Nisbet, B. S., Ranch Management "A. C. Magee, M. S., Farm Management Rural Home Research: Jessie Whitacre, Ph. D., Chief Mary Anna Grimes, M. S., Textiles Sylvia Cover, Ph. D., Foods Soil Survey: "W. T. Carter, B. S., Chief E. H. Templin, B. S., Soil Surveyor J. W. Huckabee, B. S., Soil Surveyor I. C. Mowery, B. S., Soil Surveyor Botany: V. L. Cory, M. S., Acting Chief Swine Husbandry: Fred Hale, M. S., Chief Dairy Husbandry: O. C. Copeland, M. S., Dairy Husbandman p» .,.. n s on. F. L. Th , Ph. D., Chi f; Si: t - ~ erwoo v - ~- e ' Entom§f§gaflt e a ° J. a. Couch, M. s., Assoc. Poultry Husb. o; H_ J_ Reinhard, B_ S" Entomologist Paul D. Sturkie, B. S., Asst. Poultry Hush. 1 R. K. Fletcher, Ph. D., Entomologist Agricultural Ensine¢rins= W. L. Owen, Jr., M. S., Entomologist H- P- Smith- M- S» Chi“ J. N. Roney, M. S., Entomologist Mal“ Stub“ Firm: J. C. Gaines, Jr., M. S., Entomologist -T- McNessr Supefintendellt S. E. Jones, M. S., Entomologist Aplculmre (Sail Amimh): F. F; Bibby, B. s., Entomologist H- B- Pflkfl» B- S» Chief "R. W. Moreland, B. s., Asst. Entomologist A- H- Alex- 3- 5-» Queen Breeder C. E. Heard, B. S., Chief Inspector Feed Cmltml service‘ _ c. J. Burgin, B. s., Foulbrood Inspector F- D- Fuller» M- S» Chef Agronomy Janice ISullivan, Asst. Chief. ' . S. . earce, Secretary g‘ fizgggdsivllails‘ Dgggiggfnist J. H. Rogers, Feed Inspector .4 P’ C‘ Mangelgdoljf g6 D Agronomist K. L. Kirkland, B. S., Feed Inspector if DI '1". Killough, M: s.,' Agronomist f; g- geynmdi; a". Feed I"=P°°‘°1' i J. O. Beasley, M. S., Asst. Agronomist ' ' Pom" 9e, “spector 1 Publications? E. J. Wilson. H S., Feed Inspector A D Jackson Chief H. G. Wickes, D V. M., Feed Inspector ' ' ' J. K. Francklow, Feed Inspector g SUBSTATION S i‘ No. 1, Beeville, Bee County: R. A. Hall, B. S., Superintendent No. 2, Tyler, Smith County: P. R. Johnson, M. S., Superintendent No. 9, Balmorhea, Reeves County: J. J. Bayles, B. S., Superintendent No. 10, College Station, Brazos County: R. M. Sherwood, M. S., In Charge "B. H. Hendrickson, B. S., Sci. in Soil Erosion L. J. McCall, Farm Superintendent "R. W. Baird, M. S., Assoc. Agr. Engineer No. 3, Angleton, Brazoria County: R. H. Stansel, M. S., Superintendent H. M. Reed, B. S., Horticulturist No. 4, Jefferson County: R. H. Wyche, B. S., Superintendent "H. M. Beachell, B. S., Junior Agronomist No. 5, Temple, Bell County: Henry Dunlavy, M. S., Superintendent C. H. Rogers, Ph. D., Plant Pathologist H. E. Rea, B. S., Agronomist "E. B. Deeter, B. S., Soil Erosion np_ No. B Denton, Denton County: P. B. Dunkle, M. S., Superintendent "I. M. Atkins, B. S., Junior Agronomist No. 7, Spur, Dickens County: R. E. Dickson, B. S., Superintendent B. C. Langley, M. S., Agronomist No. 8, Lubbock, Lubbock County: D. L. Jones, Superintendent Frank Gaines. Irrig. and Forest Nurs. No. 11, Nacogdoches, Nacogdoches County: H. F. Morris, M. S. Superintendent "No. 12, Chillicothe, Hardeman County: "J. R. Quinby, M. S. Superintendent "J. C. Stephens, M. A., Asst. Agronomist No. 14, Sonora, Sutton-Edwards Counties: W. H. Dameron, B. S., Superintendent I. B. Boughton, D. V. M., Veterinarian W. T. Hardy, D. V. M., Veterinarian O. L. Carpenter, Shepherd "0. G. Babcock, B. S., Asst. Entomologist No. 15, Weslaco, Hidalgo County: L. HODRiHB. B- S-, Junior Civil Engineer W. H. Friend, B. S., Superintendent S. W. Clark, B. S., Entomologist W. J. Bach, M. S., Plant Pathologist J. F. Wood, B. S., Horticulturist No. 16, Iowa Park, Wichita County: C. H. McDowell, B. S., Superintendent L. E. Brooks, B. S., Horticulturist No. 19, Winterhaven, Dimmit County: E. Mortensen, B. S., Superintendent "L. R. Hawthorn, M. S., Horticulturist Members“ ofMTeaching Staff Carrying Cooperative Projects on the Station: G. W. Adriance, Ph. D., Ilorticulture S. W. Bilsing, Ph. D., Entomology D. Sooates, A. E.,‘Agricultural Engineering A. K. Mackey, M. S., Animal Husbandry R. G. Reeves, Ph. D., Biology J. S. Mogford, M. S., Agronomy F. R. Brison, M. S., Horticulture ‘Dean, School of Veterinary Medicine. W. R. Horlacher, Ph. D., Genetics . H. Knox, M. S., Animal Husbandry A. L. Darnell, M. A., Dairy Husbandry at. O. Berry, B. S., Biology V H . T. Stewart, Ph.D., Agronomy . A. Little, M. S., Entomology TAs of September 1, 1935 "In cooperation with U. S. Department o! Agriculture. tin cooperation with Texas Extension Service. ‘In cooperation with ‘State Department of Agriculture. CONTENTS Page Introduction 4 Method of procedure 5 Vitamin A in the feed and in the eggs _________________________________________________________________ _- 7 Effect of quantity of vitamin A in the feed on mortality and Weights of the fowls ____ 7* ___________________________________ "10 Effect of quantity of vitamin A on the number of eggs produced _____________ W12 Effect of quantity of vitamin A on percentage of eggs that hatched _____ __ 13 Vitamin A requirements during the molting period _______________ ____________________ _.13 Effect of quantity of vitamin A in the feed on the vitamin A content of eggs _ . . . _ . _ . U _ . _ . , _ _ _ . e A _ . . . . . . , . _ _ . . . _ . . . _ . . . . . c U i _ 7' ’ ""14 Apparent percentage of vitamin A recovered in the eggs Units of vitamin A in excess of maintenance required for vitamin A in the eggs ..... -- l6 Vitamin A required for maintenance of laying hens _ ' - 17 Units of vitamin A required for maintenance and production of eggs high in vitamin A 19 Units of vitamin A required for laying hens without regard to the vitamin A potency of the eggs 19 Summary ........ >A 20 References ...... "21 White Leghorn hens receiving vitamin A potency from yellow corn and dehydrated alfalfa leaf meal require for maintenance and egg production approximately four units in the feed for one unit in the eggs. Requirements for maintenance seemed to be in proportion to the requirements for the eggs. The apparent per- centage of vitamin A recovered in the eggs varied from 8 -to 39, with an average of 25, the utilization being greatest just before or during the period of maximum egg production. The requirements for formation of feathers seemed to be as high as the requirements for laying eggs, since molting hens did not store vitamin A although fed liberal amounts. It is tentatively estimated that for eggs of high potency in vitamin A, hens laying 150 eggs a year would require 600 Sherman-Munsell units of vitamin A per day, or 7.5 units per gram of total feed. This can best be furnished by‘ supplementing the feed with green growing plants. If a high vitamin A potency of the eggs is not required, approximately 240 units of vitamin A per day or 3 units per gram of total feed is tentatively estimated to keep the hens in good health and main- tain a good production of eggs. Hens which have access to green feed from time to time may do well on feed containing less than 3 units of vitamin A per gram. BULLETIN NO. 514 SEPTEMBER, 1935 THE VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION R. M. SHERWOOD, DIVISION OF POULTRY HUSBANDRY, AND G. S. FRAPS, DIVISION or CHEMISTRY The necessity for vitamin A» in the feed of animals has been discussed and the approximate vitamin A potency of various feeds has been compiled in a previous bulletin (2). The vitamin A requirements of laying hens are somewhat high, as has been pointed out in previous publications (4, 5). The vitamin A potency required in poultry feeds in excess of maintenance for the production of one unit in the eggs was estimated t0 be 6.3 units when 270 units were fed daily (4), 5.7 units when 336 units were fed daily, and 4.04 units when 444 units were fed daily (5). This work was con- tinued in order to secure further information regarding the requirements of hens for vitamin A, and the number of units of vitamin Ar potency in the feed over maintenance required to produce the vitamin A in the eggs. In view of the fact that the estimation of vitamin A potency by biological methods is not very exact, some variation in the results between different experiments is to be expected. The vitamin A potency of alfalfa appears to be due chiefly to carotene, while that of yellow corn is claimed by Kuhn and Grundmann (3) to be due chiefly to cryptoxanthin. It is generally held that the vitamin A potency of vegetable materials is due chiefly to coloring matters such as carotene, but relations between the vitamin A potency of feeds and the quantity of carotene or cryptoxanthin present have not yet been worked out sufficiently to permit one to estimate from chemical analyses the vita- min A potency of a feed or food. For this reason and for the further reason that other sources of vitamin A potency besides carotene or cryp- toxthin may be discovered, we consider it best at present to use biological methods rather than chemical methods for estimating vitamin A potency. In the subsequent discussion, we have, for the sake of brevity, used the term vitamin A to mean vitamin A potency and to include alpha carotene, beta carotene, gamma carotene, cryptoxanthin, and any other chemical substances which may give rise to vitamin A potency either in the feed or in the eggs. The work here presented deals entirely with the vitamin A fed and that present in the eggs. The vitamin A may be only partly digested by . the animal, or there may be actual destruction in the process of digestion. METHOD OF PROCEDURE The White Leghorn fowls which were used in this study had been used in the experiment reported in Bulletin 493 (5). The three groups kept in pens have received the rations given in Table No. 1 since November 15,1932. When this experiment was started on December 1, 1933, there were 18 hens in the pen of the no-alfalfa group, 18 hens in the 4% alfalfa 6 BULLETIN NO. 514, TEXAS AGRICULTURAL EXPERIMENT STATION group, and 17 hens in the, 8% alfalfa group. On January 26, 1934, six hens from the pen of the no-alfalfa group and five each from the other two groups were placed in individual compartments in hen batteries. All groups in pens received yellow corn as a grain feed, and a mash containing Table 1. Ingredients of Mixtures Used for Laying Fowls in Pens Yellow corn ad lib .................................................. .. - 1f Ingredients of feed I No alfalfa 4% alfalfa 3% alfa a group group group I I I Mash I Per cent I Per cent I Per cent Ground yellow corn I 20 I 20 20 Wheat gray shorts I 29 I 29 I 29 Wheat bran I 29 I 25 I 21 50% protein meat and bone scrap .................. "I 20 I 20 I 20 Alfalfa leaf meal I 0 I 4 I 8 Chick size oyster shell ............................................. .. 1 I 1 I 1 Salt 1 I 1 I 1 I I Grain I I I 20% yellow corn (See Table 1). One group received no alfalfa meal. The second group received 4% of heat-dried alfalfa leaf meal in place of 4% of wheat bran in the mash, and the third group received 18% of heat-dried alfalfa leaf meal in place of 8% of wheat bran. These groups will be referred to as the no-alfalfa group, the 4% alfalfa group, and t-he 8% alfalfa group. The experimental period for the hens fed in pens began on December 1, 1933, and ended August 31, 1934, the duration of the experiment being 274 days. The pens in which the fowls were kept have cement floors to prevent access to green feed. The hens had an abundance of sunshine so that the equivalent of vitamin D was well supplied. The hens fed in batteries received an all-mash ration containing 65% of yellow corn (See Table 2). Those termed the no-alfalfa group received Table 2. Ingredients of Mixture Used for Laying Fowls in Batteries Ingredients of feed No-alfalfa 2% alfalfa 4% alfalfa group group \ group All-Mash I Per cent Per cent Per cent Yellow corn meal I 65 | 65 I 65 Wheat gray shorts I 12% I 11% I 10% Wheat bran .... 12% I 111A I 10% 50% protein meat and bone scrap _____________________ _, 10 I 10 I 10 Alfalfa leaf meal ______________________________________________________ __I 0 I 2 I 4 I ' I no alfalfa leaf meal; those termed the 2% alfalfa group received 2% alfalfa meal in place of part of the whzat gray shorts and wheat bran; those termed the 4% alfalfa group received 4%] alfalfa-meal in place of part of the wheat gray shorts and wheat bran. Since the birds in batteries received an all-mash ration, the 2% and 4% of alfalfa leaf meal fur- nished approximately the same amount of vitamin A as did the rations fed the hens in the pens which contained 4% and 8% alfalfa leaf meal in the mash with corn fed in addition. The experiment with the hens in VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 7 batteries began January 26, 1984, and ended August 31, 1934, a period of 218 days. The hens in the batteries were exposed to sunlight from thirty minutes to one hour once each week. Vitamin A in samples of the yellow corn and’ the alfalfa leaf meal fed and in the yolks from representative samples; of the eggs from the hens in batteries was determined by Mr. Ray Tlriechler of the Division of Qhemistry. The eggs were taken so as to represent the middle of each period and were brought promptly to the laboratory. The eggs were fed to rats in rotation. That is, an egg from the first hen was used, then an egg from the second, then an egg from the third, and so on. While the same number of eggs was fed from each hen, the hens did not all lay at the same rate, so that the period of time during which the eggs were laid was different. The modified Sherman-Munsell unit method with rats was used as we have described elsewhere in full (4). The eggs were kept in cold storage. One or more eggs were boiled; the yolk was separated and weighed; and weighed portions of the yolk were fed twice a week to the test rats. Eight to eighteen eggs. were used for each test. The rat unit of vitamin A as here used is the amount of feed fed daily in a 6-day week which will produce a gain of approximately 24 grams in eight weeks. In making the tests, the quantity of material which it was thought might make the desired gain was fed to one group of rats, and lower and higher quantities were fed to two or more other groups. The number of rats which survived, their individual weights, and the average weight of each group for the various amounts of the same feed were given con- sideration in estimating the units of vitamin A, but the most attention was paid to the quantities of feed. which gave the nearest to the desired gain of 24 grams in 8 weeks. Vitamin A in the Feed and in the Eggs Tables 3, 4, and 5 contain the average gain in weight of all the rats Table 3. Details of estimation of Vitamin A potency of feeds r . Average Units Libora- _ _ Grams Number Number gain per vitamin ory 1 Description fed of rats of rats rat in 8 A to No. daily begun at end wks_gms_ one gym 39069 Yellow corn ......................... -_ .150 6 0 .200 6 1 .250 6 4 15 3.5 39233 Yellow corn ......................... _. .200 6 1 1 .300 6 3 6 .400 6 2 32 2.5 .500 6 1 37 39294 Yellow corn _________________________ ,_ J50 6 1 -___7 .200 6 1 ~35 .300 6 3 24 3 39324 Deyhdrated alfalfa leaf meal __________________________ __ .010 8 1 _-13 .012 8 2 28 .015 6 1 28 .020 6 2 58 60 .025 6 3 43 8 BULLETIN NO. 514, TEXAS AGRICULTURAL EXPERIMENT STATION which survived, but the Weights of the individual rats which survived the entire period and of those which survived -six weeks were also considered ‘in deciding on the number of units. The total number of rats used was 634, not including those used to check the vitamin A free ration. These biological methods do not possess a high degree of accuracy, which fact must be taken into consideration in connection with the results. The heat-dried alfalfa leaf meal was of excellent quality, containing 83 units of vitamin A potency per gram at the beginning of the experiment. This was much richer in vitamin A content than ordinary alfalfa leaf meal. The yellow corn was not of very good quality with respect to vitamin A content, since it contained only 3.6 units per gram at the beginning of this experiment as compared with 7 units in the corn used for the pre- ceding experiment. Table 4. Details of estimation of vitamin A potency of egg yolk-individual hens Labora- Date I Yolk fed No. of No. of gggfigei vligginfi tory collected Group daily, rats at rats at rat in 8 to one number l grams beginning‘ end weeks, gms gram yolk I I 39399 I February I no alfalfa .067 6 1 13 I I .100 6 2 25 10 I I .150 6 3 29 39400 February I 2% alfalfa .050 6 2 15 I .067 6 4 1 I Z .100 6 4 28 11 39401 February I 4% alfalfa .040 6 0 I .050 6 4- 13 I .067 6 3 22 16 39531 March I no alfalfa .067 6 3 20 I .100 6 1 6 I .133 6 2 38 7 I I .200 I 6 5 52 39532 March I 2% alfalfa .067 6 2 —6 l .083 s a 20 l .100 s 1 s s .200 6 5 41 39533 March I 4% alfalfa .067 6 4 19 15 .083 6 6 36 .100 6 4 41 .200 6 6 73 39755 April I no alfalfa .100 6 2 16 9 .133 6 3 29 .200 6 3 45 39756 April 2% alfalfa .067 6 2 -—5 l .100 s s 15 .133 6 2 28 9 39757 April 4% alfalfa .067 6 I 6 27 18 .100 6 I 5 42 .133 6 6 62 39858 May no alfalfa .100 6 1 33 I .133 6 I 1 22 .200 I 6 I 5 21 5 39859 May 2% alfalfa .067 I 6 I 2 I ———21 l I .100 I 6 I 4 23 10 I .133 6 I 1 38 39860 May 4% alfalfa I .050 6 I 3 18 I .067 6 I 1 37 12 I I .100 6 I 3 29 40603 August I no alfalfa I .133 6 I 4 28 5 I I .200 I » 6 I 4 15 I 40604 August 2% alfalfa I .100 I 6 I r 3 11 l l .133 l s I s 2o s 40605 I August 4% alfalfa I .050 I 6 I 3 14 l l .0ss l s l 5 15 I l .010 l s l s 22 10 VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 9 It has been shown by Fraps and Treichler (1) that the vitamin A potency of corn, alfalfa, and other feeds decreases slowly while they are stored. In order to allow for this decrease, it was assumed that the rate of de- crease at the end of a month is approximately 7% of that at the beginning of the month, which is the rate found in previous work. The figures used in the calculations for the feeds are therefore corrected for the estimated loss of vitamin A. This correction is of course only approximate, a suffi- cient number of estimations not having been made to show exactly the rate of loss of vitamin A under the different conditions which affect. the loss. It is believed, however, that it is more accurate to make the correc- tions than to ignore the losses during storage. The average amount of vitamin A fed to the hens in the different pens Table 5. Details of estimation of vitamin A content of eggs before and after molt 1 | Average ‘ Units Labora- Condition Yolk fed No. of N0. of gain per vitamin tory He“ number of daily, rats at rats at rat in A to number and group molt grams beginning end 8 weeks, one gram | grams yolk Samples from individual hens—- _ 39054 9270—no alfalfa before molt .150 6 4 34 8 .200 6 4 49 .250 6 1 37 39353 9270 after molt .050 6 0 .067 6 0 .100 6 O .150 s 0 6C2) 39056 9724—4% alfalfa before molt .067 6 0 .100 6 3 12 .150 I 6 4 41 8 39256 9724 after molt .040 6 1 —24 .050 6 1 —-36 .067 6 1 3 .100 6 2 14 8 39052- 9217—8% alfalfa before molt .050 6 1 .067 6 0 .100 6 4 28 11 39257 9217 I after molt .040 6 0 ' .050 6 0 .067 6 2 11 .100 6 3 14 8 39053 9259—8% alfalfa before molt .050 6 1 31 .067 6 2 27 .100 I 6 6 30 12 Samples from pens- 38159 no alfalfa [before molt .100 6 1 0 .150 6 4 21 6 .220 6 6 41 39367 no alfalfa after molt .050 6 1 -—12 .067 6 0 .100 6 0 .150 6 1 15 6 38157 4% alfalfa I before molt .080 6 4 32 .100 6 6 26 12 .150 6 5 28 39307 after molt .040 6 0 . 0 .050 6 0 0 .067 6 0 0 .100 6 1 11 7 ( '1) .38158 8% alfalfa before molt .050 6 3 18 - .067 6 6 25 15 .100 6 6 49 39271 after molt .040 6 1 ——29 .050 6 0 .067 6 1 4 10(?) 10 BULLETIN NO. 514, TEXAS AGRICULTURAL EXPERIMENT STATION during the period of 274 days was 134 units per day for the no-alfalfa group, 209 units per day for the 4% alfalfa group, and 351 units per day for the 8% alfalfa group. This was much less than the amount fed in the work of the preceding year, the difference being due to the lower Table 6. Grams of grain and mash eaten per month perifowl in pens a M th | No-alfalfa group I 4 % alfalfa group 8 % alfalfa group on Grain I Mash Grain Mash Grain I Mash December 1262 1389 1298 1035 1348 1940 January 1376 1362 1371 1067 1430 1176 February 1516 1979 1062 1362 1103 1330 March 1394 1657 1185 1430 1444 1362 April 935 1444 781 1035 990 1135 May 981 e 1203 ‘ 717 1285 926 1457 June 781 1058 590 1221 790 1389 July 931 813 695 1081 826 1462 August 1103 813 767 994 967 1176 Total 10279 11718 8466 10510 . 9824 12427 quality of the yellow corn. The average amount of vitamin A fed to the hens in the hen batteries during the period of 218 days Was 150 units per day for the no-alfalfa group, 254 units per day for the 2% alfalfa group, and 339 units per day for the 4% _alfalfa group. The quantity of food eaten and the units of vitamin A fed per month to the fowls in pens are given in Tables 6 and 7. Table 7. Total units of vitamin A fed per month in both grain and mash in pens ' 1 Month No-alfalfa group 4% alfalfa group l 8% alfalfa group I December ............................... .. 5539 8862 12512 January .................................. -_ 5602 8730 13003 February .............................. ._ 6115 7453 12154 _ 5176 8304 12558 3432 5167 9216 3173 5621 11908 2388 4744 8785 , 2515 4390 8767 August ..................................... i. 2788 411s 7350 Total _______________________________ _. 36728 57389 96253 I I Average per day ___________________ WI 134 I 209 f 351 EFFECT OF QUANTITY OF VITAMIN A IN THE FEED ON MORTALITY AND WEIGHTS OF THE FOWLS In the pens, 6 hens died in the no-alfalfa group, 2 died in the 4% alfalfa group, and 4 died in the 8% alfalfa group. The losses in the no-alfalfa group and in the 4% alfalfa group were concentrated‘ at the end of the feeding period while the loss in the 8% alfalfa group was distributed throughout the experiment as shown in Table 8. This-suggests that the slightly higher loss in the case of the 8% alfalfa group over the 4% alfalfa VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 11 Table 8. Number of deaths of fowls in pens with, day of month on which each occurred No-alfalfa group I 4% alfalfa group I 8% alfalfa group Month Day of Day of Day of Number \ month Number month Number month December ...................... -. 0 0 I 0 January .................. .. 2 I 16, 19 0 0 February _ .... .- 0 -_-- 0 1 26 March ..... .. 0 -..- 0 0 April ._ 0 --.. 0 ._-- 1 10 May 1 26 1 29 1 26 June _. 0 _._. 1 15 O July ......... __ 2 1, 24 O 0 August .............................. -- 1 4 0 1 22 l Total .......................... _. 6 2 I 4 I group might be due to causes other than the deficiencies in vitamin A. The mortality for the hens in the pens corresponds to the mortality of similar groups as reported in Bulletin 493 (5). Of the 16 hens put in batteries, only one died, and it was from the no- alfalfa group. This death occurred on July 6, 1934. Table 9. Average Weights in grams of hens in pens No-alfalfa ‘ 4% alfalfa 8% alfalfa group I group group December ~16, 1933 ................ .. 1629 1670 1584 1556 1525 1439 1560 1531 1452 1600 1499 1415 1632 1480 1431 1580 1443 1395 1496 1451 1354 1439 1426 1369 September 1 .......................... __ 1543 1420 1425 Average ......................... -- 1559 1494 1429 The weights of the hens are given in Tables 9 and 10. There seems to be no relation between the vitamin A in the feed and the weights of the fowls in the work here reported. In fact, the fowls in the no-alfalfa group were heavier than the fowls receiving alfalfa. This differs from the results previously reported (4, 5). Table 10. Average weights in grams of hens fed individually No-alfalfa 2% alfalfa 4% alfalfa group gTOIIL) group February 1, 1934 ................. .. 1573 1556 1590 March 1 -_._-..-_-_-_-..---_---_-._._. 1774 1661 1679 April 1 ............ _-_ ........... _- 1763 1672 1699 May 1 _ .............................. _. 1700 160s 1659 June 1 .......................... -_ 1675 1656 1617 July 1 ----- ___ ............. -. 1600 1634 1653 August 1 ...... .. . 1756 1612 159s September 1 .......................... -. 1795 1571 1537 Average 1705 1621 1635 12 BULLETIN NO. 514, TEXAS AGRICULTURAL EXPERIMENT STATION Effect of Quantity of Vitamin A on the Number of Eggs Produced Tables 11 and 12 give the number of eggs producedby the hens in the pens and in the batteries. It is noted that the hens in the pens receiving 8% alfalfa laid considerably more eggs than did those receiving no alfalfa, but the hens receiving 4% alfalfa laid fewer eggs than did the group which received no alfalfa. The hens in the battery receiving 2% Table 11. Average number of eggs per fowl in pens N o-alfalfa 4% alfalfa 8% alfalfa Month group I group I group December ............................... _-_ 7.4 7.8 I 9.2 January . . . . . . . _ . _ _ __ 13.8 11.8 15.4 February .. . _ 12.9 10.3 12.5 March ..... __ 15.5 12.6 16.0 April - , 10.6 8.9 12.7 May - ~-—-~ 11.0 10.2 13.1 June 6.0 6.6 16.1 July ----- -- _ 1.5 3.7 8.1 August .................................. ..| 5.4 3.3 6.4 Total ................................. _. 84.1 75 2 109 5 alfalfa laid more eggs than did those receiving 4% alfalfa, and the fowls receiving 4% alfalfa laid more eggs than did those receiving no alfalfa. These data come from very small numbers of hens. If all of the hens were grouped together, the data would show a low egg production for the no-alfalfa group, a larger egg production for the group receiving Table 12. Average feed consumption and egg production by months per hen in batteries I No alfalfa lot I 2 % alfalfa I 4 % alfalfa I GramsI No. I GramsI GramsI No. I GramsI Grams No. I Grams I feed I eggs I eggs I feed I eggs I eggs I feed eggs I eggs January 6 daysI 554.3 I 3.67 I 194.2 722.8 I 3.0 153.0 521.2 3.6 192.0 February I 2946.7 I 13.67 716.8 2922.0 I 19.4 1034.6 2899.0 17.2 938.6 March I I 3570.0 I 15.67 I 846.7 3128.0 I 21.0 1113.6 3149.0 16.0 869.2 April I 2596.7 I 7.67 I 395.2 2866.0 I 14.6 755.2 2526.0 9.4 494.6 May I 2383.0 I 9.33 I 466.5 2528.0 10.8 539.6 2406.0 10.2 529.4 June I 2268.0 I 7.80 366.5 2226.0 I 10.2 493.4 1952.0 5.6 289.8 July I 2263.0 I 7.00 I 338.0 2264.0 I 10.2 491.0 2032.0 I 8.4 429.6 August I 1904.0 2.80 I 130.4 I 1658.0 I 5.8 290.0 1833.0 I 4.6 225.0 Total I18485.0 I 67.61 'II 3454.3 I18314.8 I 95.0 4870.4 I173l8.2 I 75.0 I 3968.2 the larger amount of alfalfa, and the largest egg production for the group receiving the largest amount of alfalfa. This is closely in line with data previously published in Bulletin 493 (5). VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 13 EFFECT OF QUANTITY OF VITAMIN A ON PERCENTAGE OF EGGS THAT HATCHED In previous experiments it has been shown that there is a rather close relationship between the vitamin A fed to hens and the number of eggs that hatched. The results secured in this present experiment (See Table 13) show that the percentage of eggs that hatched from the hens re- ceiving the smaller amount of vitamin A was 33 to 42 and that from the Table 13. Relation of percentages of eggs which hatched to vitamin A in feed of hens No-alfalfa 4% alfalfa I 8% alfalfa Date No. of group, 134 No. of group, 209 I No. of group, 351 hatched eggs units vitamin eggs units vitamin eggs units vitamin A fed per day A fed per dayI A fed per day I I % hatched ' I % hatched I I % hatched March 2, 1934 48 I 41.67 I 49 I 75.51 I 52 I 78.85 I I I April 2, 1934 51 I 33.33 I 101 I 70.30 I 51 I 68.63 I I April 15, 1934 53 33.96 I 51 I 68.63 I 101 I 69.31 I I ' April 25, 1934 51 35.30 I I I I Total I I I I I or average 203 I 35.96 I 201 I 71.14 I 204 I 71.57 hens receiving the larger amount of vitamin A was from 69 to 79. It was thought possible that there might be a storage of vitamin A during the molting period, which lasts from 6 weeks to 2 months or longer, especially by hens which were being fed high amounts of vitamin A. Such storage should show the vitamin A content of the eggs higher at the end of the molting period than at the beginning, and the eggs laid at the end of the molting period should contain more vitamin A than those laid before molting. In order to test this possibility, vitamin A potency was estimated in eggs collected just before the molting period from three pens and also from four individual hens, and in eggs from the three pens and from the individual hens which remained at the end of the molting period. The vitamin A potency of these eggs is shown in Table 14. The vitamin A potency of all the eggs is low. The individual hens Table l4. Effect of ‘molt on vitamin A potency in the egg yolk Hen number and Condition of Vitamin A units group of molt per gram 9270- no alfalfa. before molt 8 after molt 6 9724—4% alfalfa before molt 8 after molt 8 9217—8% alfalfa before molt 11 after molt 8 9259~—8% alfalfa before molt 12 hen died ' Pen— no alfalfa before molt 6 ' after molt 6 Pen—- 4% alfalfa before molt 12 after molt 7 (i?) Pen— 8% alfalfa before molt 15 after molt 10 ('2) 14 BULLETIN NO. 514, TEXAS AGRICULTURAL EXPERIMENT STATION fed the 8% alfalfa and no alfalfa produced eggs containing less vitamin A after molting than before molting. The hen receiving the 4% alfalfa produced eggs containing the same vitamin A content before and after molting. The hens in the pens receiving no alfalfa produced eggs con- taining the same number of units of vitamin A before and after molting, while the other two lots produced eggs containing less vitamin A after molting. There is thus no evidence of a storage of vitamin A during the molting period. It would appear that the requirements for vitamin A per gram of feed in the formation of feathers may be as great as for the production of eggs. The consumption of feed, and therefore the con- sumption of vitamin A, is less during the molting period than during the period of egg production. EFFECT OF QUANTITY OF VITAMIN A IN THE FEED ON THE VITAMIN A CONTENT OF THE EGGS These calculations are made entirely from the work with the hens fed individually in the batteries. Table 15. Units of vitamin A per gram of egg yolk and of feed calculated from Tables 3 and 4 Date l Eggs I l Collected I No-alfalfa. I 2 % alfalfa I 4 % alfalfa I Alfalfa I Corn I group I group I group I I l l December I 83 I 3.6 January 6 7 1 0 I 7 8 I 3.4 February 10 11 16 I 73 I 3.2 March 7 s 15 I es | 3.0 April 9 9 18 64 I 2.8 May 5 10 12 60 I 2.6 June 5 8 11 I 56 I 2.4 July (assumed) 5 6% 10% I 53 I 2.3 August 5 6 9 % I 5O I 2.2 The units of vitamin A per gram of yolk in the eggs collected at dif- ferent times are given in Table 15. Since the hens had been fed pre- viously upon rations containing li-mited amounts of vitamin A and had Table 16. Comparison of units of vitamin A in eggs of hens fed different quantities of vitamin Buletin 468, 1932 work I Bulletin 493, 1933 work I 1934 work O 120 220 224 336 444 150 254 339 Month units units units units units units units units units fed fed fed fed fed fed fed fed fed l l November 20 12 I 13 I 25 December _ 12 12 22 2O I 23 . . January 14 10 I 10 I 12 16 I 20 6 7 10 February 1O m. 14 I 17 I 16 I 22 1O 11 16 March 6 5 I 12 13 13 7 8 14 April ___. 11 I 13 I 14 9 9 18 May 5 8 I I 8 I 15 14 5 1O 12 June I I 7 I 15 I 17 5 8 11 July ___. I I 6I2 13% I 16 5 I 6% 10% August I l 6 1 12 I 15 5 I 6 I 9 V; VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 15 not been able to store vitamin A duringgthe molting period, the quantity present in the eggs was 10w at the beginning of this experiment. There is an increase in the vitamin A content during the first month of feed- ing followed by a decrease. Table 16 contains a comparison of the vitamin A content found in the eggs in this experiment with that of the two previous experiments (4, 5). The hens used in the previous experiments (5) had had ample opportunity to store vitamin A from access to green grasses and pasture before being placed on experiment. In the 1933 work, the hens seemed to have more vitamin A stored at the beginning of the work than those in either of the other two years, since the eggs contained more vitamin A at that time. In both 1932 and 1933, there was a gradual decrease of vitamin A in the eggs during the laying period. In the 1934 work, with the vitamin A content at the beginning at a low level, there was some increase in the vitamin A content during the laying period followed by a decrease to approximately the same quantities as at the beginning. Apparent Percentage of Vitamin A Recovered in the Eggs The quantities of vitamin A fed to the fowls and the quantities in the eggs were calculated from the data secured, as was done in previous work. Table 17. Corn and alfalfa leaf meal in grams consumed per hen in batteries N0 alfalfa lot I 2% alfalfa lot I 4% alfalfa lot Corn- Corn I Alfalfa I Corn I Alfalfa I January, 26-31 360.3 469.8 14.46 338.8 20.85 February 1915.4, 1899.3 58.44 I 1884.4 115.96 March 2320.5 2033.2 62.56 I 2046.9 125.96 April 1687.9 1862.9 57.32 I 1641.9 101.04 May 1549.0 1643.2 50.56 I 1563.9 96.24 June 1474.2 1446.9 44.52 I 1268.8 78.08 July 1471.0 1471.6 45.28 1320.8 81.28 August 1237.6 1077.7 33.16 1191.5 73.32 Table 12 shows the feed consumption and egg production per hen, while Table 17 shows the grams of corn and alfalfa leaf meal consumed per hen per month. The units of vitamin A in the feed and in the eggs per ‘Table 18. Units of vitamin A in feeds and eggs per hen in batteries I No alfalfa lot I 2% alfalfa lot I 4% alfalfa lot I Corn Eggs I Corn I Alfalfa I Eggs I Corn I Alfalfa I Eggs January 1225.0 388.4 1597.3 1127.9 357.0 1151.9 1626.3 640.0 February 6129.3 2389.3 6077.8 4266.1 3793.5 6030.1 8465.1 5005.9 March 6961.5 1975.6 6099.6 4254.1 2969.6 6140.7 8565.3 4346.0 April 4726.1 1185.6 5216.1 3668.5 2265.6 4597.3 6466.6 2967.6 Ma)’ 4027.4 777.5 4272.3 3033.6 1798.7 4066.1 5774.4 2117.6 June 3538.1 610.8 3472.6 2493.1 1315.7 3045.1 4372.5 1062.6 July 3383.3 563.3 3384.7 2399.8 1063.8 3037.8 4307.8 1503.6 August 2722.7 217.3 2370.9 1658.0 580.0 2621.3 3666.0 712.5 Total ' 32713.4 8107.8 32491.3 22901.1 14143.9 30690.3 43244.0 18355.8 I Total fed 32713.4 I 55,3924 73,934.3 I Average I per day 150 | 254 339 I 16 BULLETIN NO. 514, TEXAS AGRICURTURAL EXPERIMENT STATION month is shown in Table 18. Table 19 shows the apparent percentages * recovered in the eggs. As these fowls did not have as much vitamin A stored at the beginning of the experiment as the fowls used in the previous experiments, the vitamin A recovered comes nearer showing the actual utilization of the vitamin than the previous work. However, part of the vitamin A consumed was used for maintenance and part for the production of eggs, while some of it remained undigested or was lost. The apparent percentage of vitamin A recovered averaged about 25, Table 19. Apparent percentage of vitamin A recovered in eggs l No alfalfa l 2% alfalfa l 4% alfalfa l l l January ................................. -.l 31.7 13.1 l 23.0 February ................................. ..l 39.0 36.7 l 34.5 March .......................................... ..l 28.4 28.6 l 29.6 April .................................... ..’ ...... ..l 25.1 25.5" l 26.8 May 19.3 24.6 | 21.5 June __ .1 17.3 22.1 l 14.3 July _ ( ' 16.7 18.4 l 20.5 August . __..l 8.0 14.4 l 11.3 I I Average ._ .. ._ . ,l 24.8 25.5 l 24.8 but it varied from 8 to 39. It was the highest in the second month of the experiment (February) and lowest in the last month (August). In 1933, the average percentage recovered varied from 8.9 to 59.7, with an average of about 27. The recovery was highest in February or March. The high- est apparent recovery of vitamin A in the eggs is near the period of maximum production of eggs. Units of Vitamin A in Excess of Maintenance Required for Vitamin A in the Eggs Details of the data necessary to calculate the utilization of vitamin A for the eggs have been given in previous tables. If we assume that the maintenance requirement is the same for each group, it is cancelled when one is subtracted from from the other, and the balances are the requirements for the eggs. The calculations are given in Table 20. The fowls in the 2% alfalfa group produced eggs containing 6036 more units of vitamin A than the fowls in the no alfalfa group. They consumed 22,679 more units of vitamin A in; the feed, so that units in the feed re- quired for one unit in the eggs were 3.76. A similar comparison between the fowls of the 4% alfalfa group and those of the 2% alfalfa group gave 4.4 units in the feed required for one unit in the eggs, and a com- parison of the fowls in the 4% alfalfa group with those of the no alfalfa group gave 4.02 units required in the feed for one unit in the eggs. These hens went on experiment with low quantities of vitaminA stored in their bodies. In our previous results (4, 5) we estimated that one unit in the eggs required 6.3 units in the feed at 270 units fed daily, 5.7 units when 336 units were fed daily, and 4.01 when 444 units were fed daily to pullets which were put on experiment with good amounts of vitamin A stored. In the experiment at lower level of vitamin A intake, 6.3 units in the feed VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 17 were estimated to be required for one unit in the eggs. The results se- cured in the experiment here reported agree remarkably well with the results previously secured, especially when the difficulties associated Table 20. Units of vitamin ‘A potency required for the units of vitamin A in the eggs In eggs, 2% alfalfa group ____________________________________________________________________________________________________ .. 14,143.9 In eggs, no-alfalfa group _________________________________________________________________________________ ll l. l 8,107.8 Difference in eggs due to 2% alfalfa _________________________________________________ l. l. l l 6,036.1 In feed, 2% alfalfa group ______________________________________________________________________ .. l . 55,3924 In feed, no-alfalfa group ________________________________________________________________________________________________ .l 32,7134 Difference in feed due to 2% alfalfa .................................................... .. ....... .l 22,6791) Units in feed required for one unit in eggs,‘ no-alfalfa versus 2% alfalfa ................................................................... .l ll l . l l l. ll 3.76 In eggs, 4% alfalfa group _________________________________________________________________________________________________ l. .. 18355.8 In eggs, 2% alfalfa group llllllllllllllllllllllllllllllllllllllllllllllllll .. 14,1431) Difference in eggs due to 2% alfalfa llllllllllllllllllllllllllllllllllllllllllllllllllll ll 4,211.9 In feed, 4% alfalfa group _____________________________ .. .l 73,9343 In feed, 2% alfalfa group“.-. _________________________________________________________________________ .. .. l ll l . 55,417.1 Difference in feed due to 2% alfalfa llllllllllllllllllllllllllllllllllllllllll . l. l. ll 18,5172 Units in feed required for one unit in eggs, 2% alfalfa versus 4% alfalfa lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll ll .l 4.40 In eggs, 4% alfalfa group _________________________________________________________ l. l l 18,3558 In eggs, no-alfalfa group... l ........ .. l lllll ll 8,107.8 Difference in eggs due to 4% alfalfa ................................................... 10,2481) In feed, 4% alfalfa group .................................................................................. l 73,934.53 In feed, no-alfalfa group .......................................................................................... . l 32,7134 Difference in feed due to 4% alfalfa ..................................................... .. l. 41220.4 Units in feed required for one unit in eggs, no-alfalfa versus 4% alfalfa ...................................................... 4.02 with the exact estimation of vitamin A potency in feeds and eggs are taken into consideration. Vitamin A Required for Maintenance of Laying Hens Since the vitamin A in the eggs was approximately the same at the beginning and at the end of the experiment, it would appear that there was little loss or gain of vitamin A by the bodyof the‘ hen during the experi- ment. If this is the case, it should be possible to calculate the amount of vitamin A required for maintenance as well as for the eggs. Attempts were made to calculate the maintenance requirements of lay- ing hens from the data. These calculations are given in Table 21. If it is assumed that 4 units in the feed are required for one unit in the eggs, and that the balance is left for maintenance, we find that practically 18 BULLETIN NO. 514, TEXAS AGRICULTURAL EXPERIMENT STATION nothing is left for maintenance. If we assume that one unit in the eggs requires three in the feed (Table 21), the amount left for maintenance differs widely for the three tests and increases with the quantity fed. The same applies (Table 21) to the calculations made on the assumption that 2 units in the feed are required for one unit i_n the egg. By either method of calculation, varying values for maintenance are secured, and these values are obviously incorrect. The quantities of vitamin A required for maintenance are apparently di- rectly proportional both to the quantities fed and to the quantities in the eggs. It would seem that the maintenance requirements of vitamin A for the laying hens are not a constant value and cannot be separated from the requirements for vitamin A in the eggs. The maintenance requirement for the period studied in the work here presented appears to be directly proportional to the vitamin A in the eggs. Table 21. Attempted calculation of maintenance requirement of laying hens for vitamin A No-alfalfa I 2% alfalfa 4% alfalfa group group group Units of vitamin A in eggs .............................. 8108 14144 18356 Units of vitamin A in feed __________________________________ _. 32713 55392 » 73934 Units required in feed for eggs if 4 units in feed is required for 1 unit in eggs .............. ._ 32432 56576 73424 Balance for maintenance (218 days) ____________ .. 281 ’ 0 510 Maintenance per day ........................................... ._ 1.3 0 2.3 Units of vitamin A in feed ______________________________ __ 32713 55392 73934 Units required in feed for eggs if 3 units in feed is required for 1 unit in eggs .............. _. 24324 42432 55068 Balance for maintenance (218 days) ______________ .. 8389 12960 18866 Maintenance per day ___________________________________________ _. 38.5 59.4 I 86.5 Units of vitamin A in feed ________________________________ 1 32713 55392 73934 Units required in feed for eggs if 2 units 0f feed is required for 1 unit in eggs ......... .. 16216 ' 28288 36712 Balance for maintenance (218 days) .............. .. 16497 I 27104 A 37222 Maintenance per day ........................................... 11 75.7 I 124.3 170.7 I I Approximately the four units in the feed required for one unit in the eggs also include maintenance. Considering again the apparent percentage recovery of vitamin A in the eggs as given in Table 19 of this publication, and in Table 11 of Bulletin 493 (5), we can conclude that hens may utilize more than 25 per cent oftthe vitamin A potency in their feed at periods of heavy laying, thus leaving part of the average requirement to be used for maintenance during other periods. We conclude that the requirements of laying hens for both maintenance and production are approximately 4 units of vitamin A in the feed for one unit in the egg. VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 19 Units of Vitamin A Required for Maintenance and Production Of Eggs High in Vitamin A The vitamin A content of the eggs at the beginning of the laying period will depend upon the vitamin A stored by the fowl. If the hen has access to green feed so that she can store a good amount of vitamin A, the eggs will contain (Table 16) about 20 to 25 units vitamin A per gram of yolk. If the feed contains insufficient supplies of vitamin A, the eggs may con- tain as little as 6 units per gram (see Table 16). The effect of the vitamin A in the feed upon the vitamin A in the eggs will thus depend upon the previous feed of the bird. If the vitamin A content of the eggs is high at the beginning of the laying period, the eggs will decrease gradually in vitamin A potency, unless the hens are fed large quantities of vitamin A such as are contained in green growing plants. It is possible from the work here presented to estimate approximately the quantity of vitamin A required by laying hens to produce eggs of high potency. It would seem that adequate amounts can best be furnished by access to green feed. If we estimate that it requires 4 units of vitamin A potency in the feed to produce one unit in the egg, an egg with a yolk weighing 15 grams and containing 20 units vitamin A to the gram of yolk would require 1200 units of vitamin A. Hens laying 150 eggs in 10 months, or 15 eggs a month, would require 600 units per day. This is appreciably more than the 444 units used in any of our experiments. During the molting season, equally as much would be required, if we judge from the work reported in this Bulletin. If the fowls eat 80 grams of mash and grain, they should require 7.5 units of vitamin A per gram of feed to supply the 600 units of vitamin A needed. This might be met by an all-mash feed containing 10% of alfalfa leaf meal having an average vitamin A potency of 75 units per gram. Such alfalfa leaf meal would be of very high quality and 10 per cent is too large to include in an all-mash feed. As stated in the previous bulletins (4, 5), this high quantity of vitamin A can be supplied best by supplementing the feed with fresh green growing plants such as alfalfa, clovxer, mustard, spinach, turnip greens, oats, wheat, or grasses. Sprouted oats, cabbage, lettuce, or similar light col- ored green feeds are not sufficiently rich in vitamin A for the purpose. Units of Vitamin A Required for Laying Hens Without Regard to the Vitamin A Potency of the Eggs If the vitamin A content of the eggs is disregarded, it is possible to main- tain egg production and avoid extensive losses of fowls with amounts of vitamin A less than that required for the production of eggs of high potency. While much more work is necessary to decide exactly on the quantities so needed, it is possible to form a tentative estimate from the work we have presented. 2o BULLETIN NO. 514, TEXAS AGRICULTURAL EXPERIMENT STATION Yellow corn in large amounts furnishing from 150 to 224 units a day does not seem to contain enough vitamin A to keep the hens in good health and maintain production of eggs. There was greater mortality with these hens than with the others, the hatchability of the eggs was less, and ther is the possibility that the fowls would be susceptible to other diseases. The rations containing 4% of alfalfa leaf meal, averaging from 251 to 336 units per day (See Table 16), seem to provide sufficient vitamin A for health and to maintain good egg production. The vitamin A require- ment may be a little less than this. We make the tentative estimate of about 240 units of vitamin A per day as the requirement for White Leghorn hens laying about 150 eggs a year when the vitamin A content of the eggs is not considered of im- portance.‘ Additional work is required to make this estimate more exact, but in the meantime it should be useful. The hens in the experiment consumed on an average 80 grams of feed per day. The feed should therefore contain 3.0 biological units of vitamin A per gram. This amount would be distributed between the mash and the scratch feed or come from green feed. If the scratch feed is low in vitamin A, the mash must be high, unless the hens have access to green feed. Hens which have access to green feed from time to time may store up con- siderable amounts of vitamin A and get along on less than the amount stated above. SUMMARY Three groups of White Leghorn hens were fed different amounts of vitamin A potency from yellow corn and dehydrated alfalfa leaf meal. Some of the hens were fed individually in batteries and the others in pens. The vitamin A potency of the feeds and in the eggs of the hens fed indi- vidually' was estimated by the Sherman-Munsell biological method. The mortality was greatest with the hens which received the least vitamin A. No significant differences were observed in the weights of the birds in the three groups. On an average, the lowest egg production was from the birds receiving the least vitamin A and the highest production from those receiving the most vitamin A. The percentage of eggs that hatched was low, 33 to 42% for the hens receiving the smallest amount of vitamin A and 69% to 79% for those receiving the other amounts. . The eggs produced after molting were either lower in vitamin A content than before molting or the same. The units per gram of feed for the formation of feathers seem to be as high as the requirements for egg production. There apparently was no storage of vitamin A during the molting period by hens receiving as much as 8% alfalfa leaf meal in the mash. The hens entered the, experimental period with eggs low in vitamin A. There was an increase in vitamin A in the eggs during» the first month of the feeding period followed by a decrease. The increase was greatest with the hens receiving the most vitamin A. The apparent percentage of vitamin A recovered in the eggs averaged VITAMIN A REQUIREMENTS OF HENS FOR EGG PRODUCTION 21 about 25% of that in the feed, but the percentage recovered during dif- ferent months varied from 8 to 39. The highest apparent recovery is just before or during the period of maximum egg production. On an average, four units in the feed were required for one unit of vitamin A potency in the egg. This may be compared with 6.3 units re- quired at low levels in the 1932 work, or with 5.7 and 4.4 at higher levels in the 1933 work. Since the hens at the beginning and at the end of the experiment laid eggs containing approximately the same quantity of vitamin A, there was probably little loss or gain of vitamin A by the hens. The require- ments for maintenance could not be separated from the requirements for the eggs. The four units in the feed required for one unit in the egg were ap- parently sufficient both for the eggs and for maintenance. Hens during period of heavy laying apparently may utilize more than the 25% of the vitamin A potency in the feed needed for the eggs, leaving some for maintenance. It is estimated that hens laying per year 150 eggs high in vitamin A would require approximately 600 Sherman-Munsell biological units of vita- min A per day, or 7.5 units per gram of feed. This high requirement can best be met by allowing the fowls access to dark-green growing plants. It is estimated that if the vitamin A content of the eggs is disregarded, laying hens may be kept in good health and produce eggs in good quanti- ties on approximately 240 units of vitamin A per day, or 3 units per gram of total feed. This estimate is tentative but should serve a useful pur- pose until more accurate estimates can be made. Hens which have access to green feed from time to time may do well on feed containing less vitamin A than here estimated. REFERENCES 1. Fraps, G. S., and Treichler, R. 1933. Losses of vitamin A in dry- ing fresh raw carrots and sweet potatoes and canned spinach. Re- printed from Jour. of Agri. Research, 47:539-541. 2. Fraps, G. S., and Treichler, R. 1933. Vitamin A content of foods and feeds. Tex. Agr. Exp. Sta. Bull. 477. 3. Kuhn, Richard, and Grundmann, Christoph. 1933. The growth vitamin. V. Cryptoxanthin, a xanthophyll of the formula C40 H56 O. Berichte 66B: 1746. Chemical Abstracts. 2821043. 4. Sherwood, R. M., and Fraps, G. S. 1932. The quantities of vitamin A required by pullets for maintenance and for egg production. Tex. Agr. Exp. Sta. Bull. 468. 5. Sherwood, R. M., and Fraps, G. S. 1934. The amount of vitamin A potency required by hens for egg production. Tex. Agr. Exp. Sta. Bull. 493.