UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA A STUDY OF THE RELATIVE VALUE OF CERTAIN ROOT CROPS AND SALMON OIL AS SOURCES OF VITAMIN A FOR POULTRY D. E. DAVIS AND J. R. BEACH BULLETIN 412 NOVEMBEK, 1926 UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY. CALIFORNIA 1926 Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://www.archive.org/details/studyofrelativev412davi A STUDY OF THE RELATIVE VALUE OF CERTAIN ROOT CROPS^ AND SALMON OIL AS SOURCES OF VITAMIN A FOR POULTRY D. E. DAVIS2 AND J. E. BEACH3 In 1925 Davis and Beach* reported studies of the relative value, as sources of vitamin A for poultry, of several succulent feeds. The only root crops included were a small sized market variety (exact variety unknown) of carrots and one variety of mangel beets. The carrots proved to be as good a source of vitamin A as green barley, alfalfa, clover, etc., but the mangel beets were apparently worthless. The purpose of this experiment was to determine if other varieties of root crops which give a larger yield than the variety of carrots used in the previous experiments would provide a sufficient amount of vitamin A to make them satisfactory substitutes for green food in poultry rations. Since vitamin A is commonly associated with the pigments, xanthophyll, chlorophyll, and carotin, color was the basis upon which the selection of varieties of roots used was made. All varieties of carrots, mangel beets, and turnips that are grown to any extent in this state were roughly classified as red, yellow, or white. For use in these tests one variety of carrots, beets, or turnips was selected as representative of all varieties of that color class. The varieties selected were as follows : Yellow Giant carrot, representing the yellow carrots. Danvers Half Long carrot, representing the red carrots. White Belgian carrot, representing the white carrots. Mammoth Long Red mangel, representing the red mangels. Golden Tankard mangel, representing the yellow mangels. 1 Tests of the roots used were carried out with the cooperation of G. W. Hendry, Division of Agronomy, University of California, who has made cultural studies of California root crops. Mr. Hendry classified, selected, and provided all roots used in these trials. Those desiring information regarding yield, adaptability for any section of the state, etc., are referred to G. W. Hendry, College of Agriculture, University of California, Berkeley, Calif. 2 Junior Veterinarian in the Experiment Station. 3 Assistant Professor of Veterinary Science, Associate Veterinarian in the Experiment Station. 4 Davis, D. E., and J. E. Beach. A study of the relative values of certain succulent feeds and alfalfa meal as sources of vitamin A for poultry. California Agr. Exp. Sta. Bui. 384:1-14. fig. 1. 1925. 4 UNIVERSITY OP CALIFORNIA EXPERIMENT STATION Half Sugar mangel, representing the white mangels. American Purple Top Swede turnip, representing the yellow or rutabaga turnips. Purple Top White Globe turnip, representing white turnips. Fish oils in general have been found to contain vitamin A, but cod-liver oil is the one commonly used. Salmon oiP is available in large quantities on the Pacific coast, and is less expensive than cod-liver oil. It was, therefore, thought worth while to determine if this oil would make a satisfactory substitute for cod-liver oil as a source of vitamin A for poultry. PLAN OF THE EXPERIMENT The general plan of the experiment was to feed fowls a basal ration which previous experiments^- "^ had shown to be deficient in vitamin A and to supplement this with different varieties of mangels, carrots, and turnips or salmon oil. The basal ration was a dry mash mixture, consisting of 25 per cent each of bran, shorts, and ground barley, 10 per cent of soybean meal and 15 per cent of meat scrap, which was constantly before the birds in hoppers, and a scratch grain mixture, consisting of equal parts of wheat, barley, and white Egyp- tian corn, which was fed twice .daily in the litter. Shell was available at all times. The birds were confined in houses which had tight board floors covered with shavings for litter. A weighed amount of a supplement was fed daily, except Sunday, to each bird. The supplements were fed in a specially constructed coop.^ Birds which did not voluntarilj^ consume all of their daily supply were forcibly fed the remainder. The finely chopped carrots, mangels, and turnips were placed in cups suspended on the sides of the feeding coop. The salmon oil was introduced into the esophagus with a pipette. One hundred pullets, all of which were from the same brood of chicks, were divided into ten groups of ten birds each when three months of age and supplied the basal ration and an abundance of green food. The purpose of this was to have them all in as nearly 5 The manufacturers who supplied the oil stated that it was extracted from salmon cannery refuse consisting of heads, tails, fins, and viscera, including the liver, and contained not more than 4.16 per cent free fatty acid. 6 Beach, J. E. Studies on a nutritional disease of poultry caused by vitamin A deficiency. California Agr. Exp. Sta. Bui. 378:1-22. figs. 1-7. 1924. 7 Davis, D. E., and J. E. Beach, op. cit., p. 4. 8 Davis, D. E., and J. E. Beach, op. cit., p. 5. fig. 1. BUL. 412 A STUDY OF SOURCES OF VITAMIN A FOR POULTRY 5 the same condition as possible when the experimental feeding was started. On October 19, when the pullets were four months of age, they were leg-banded and experimental feeding was begun as indi- cated in table 1. TABLE 1 Group No. Bird No. Ration I 1-10 Basal ration plus Yellow Giant carrot II 11-20 Basal ration plus Mammoth Long Red mangel III 21-30 Basal ration plus Danvers Half Long carrot (red) IV 31-40 Basal ration plus Golden Tankard mangel (yellow) V 41-50 Basal ration plus White Belgian carrot VI 51-60 Basal ration plus Half Sugar mangel (white) VII 61-70 Basal ration plus American Purple Top Swede turnip (yellow) VIII 71-80 Basal ration plus Purple Top White Globe turnip IX 91-100 Basal ration plus salmon oil X 101-110 Basal ration only. Control pen At the beginning of the experiment the daily amount of supple- ment, except salmon oil, was arbitrarily fixed at one gram^ to a bird. The amount of salmon oil was one cubic centimeter. The daily amount of any supplement was doubled for all birds in a group whenever any bird in that group exhibited definite indications of vitamin A deficiency. The amount of the supplement was again doubled when- ever the condition of the birds indicated that they were still getting an insufficient amount of vitamin A. The appearance of either the characteristic ophthalmia, or pustules in the mouth or esophagus, described by Beach,^" was regarded as a definite indication of vita- min A deficiency. 9 A record of the mash and grain consumption was kept in order to determine what percentage of the total food consumption the supplement constituted. The average daily consumption to a bird over the period of ninety-six days in groups I and III, the only groups in which no birds died from any cause, was fifty-nine grams of mash and thirty-six grams of grain. Calculated on the basis of this average (ninety-five grams daily) the percentage of supplement in the total amount of feed consumed was as follows : One gram of supplement daily 1.0 per cent of the total ration Two grams of supplement daily 2.0 per cent of the total ration Four grams of supplement daily 4.0 per cent of the total ration Eight grams of supplement daily 7.7 per cent of the total ration Sixteen grams of supplement daily 14.4 per cent of the total ration Thirty-two grams of supplement daily 25.2 per cent of the total ration One cubic centimeter of salmon oil daily is equivalent to 1.0 per cent of the total ration. These amounts represent the percentage of supplement to the total food con- sumption of healthy chickens. The birds which sickened consumed less grain and mash, therefore the percentage of supplement in the total food consumption of such birds was considerably higher. 10 Beach, J. E., op. cit., pp. 3, 4. figs. 1-7. b UNIVERSITY OF CALIFORNIA EXPERIMENT STATION All birds were weighed and examined at weekly intervals. The experimental feeding began October 19 and continued until January 22, a period of ninety-six days. RESULTS OBTAINED IN THE DIFFERENT GROUPS Group I — Basal ration phis Yellow Giant carrot. The amount of Yellow Giant carrot was maintained at one gram daily throughout the experiment. No lesions of nutritional disease appeared and no birds died from any cause. The average weight of the birds in this group increased from 1105 grams on October 16 to 1570 grams on January 22, the close of the experiment, a gain in weight of 42 per cent during the ninety-six days of experimental feeding. Seventeen eggs were produced in this pen before the birds were six months of age. The production from December 12, the day the birds were six months of age (fifty-fifth day of the experiment) until the close of the experiment was 30.4 per cent. A total of 145 eggs was produced. Group II — Basal ration plus Mammoth Long Red mangel. The amount of Mammoth Long Red mangel was maintained at one gram daily until November 27, the fortieth day of the experiment. On this date two birds, 14 and 16, showed pustules and bird 13 died. A post-mortem examination, however, failed to show any evidence of nutritional disease in bird 13. The amount of mangel was increased to two grams daily on November 28. On December 4 (the forty- seventy day) two more birds (15 and 20) showed lesions in the esophagus. The amount of mangel was increased on December 5 to eight grams daily. On December 7 three birds, 12, 14, and 16, died of nutritional disease. Bird 12 showed no external lesions prior to death. On December 11 (the fifty-fourth day) one new case (in bird 19) of nutritional disease appeared. The amount of mangel was increased to sixteen grams daily on December 12. Bird 19 which had previously shown pustules developed ophthalmia on December 24 (the sixty-seventh day). The amount of red mangel was increased to thirty-two grams daily on December 25. This amount constituted 25.2 per cent of total food consumption of the birds and was more than they would voluntarily consume in two hours. On December 27 (the seventieth day) bird 19 died of nutritional disease and on January 6 (the eightieth day) bird 15 died from the same cause. Birds 11 and 18 first showed pustules on December 31 (the seventy- BUL. 412] A STUDY OF SOURCES OF VITAMIN A FOR POULTRY 7 fourth day) and lesions in bird 17 first appeared on January 15 (the eighty-ninth day). Nine (90 per cent) of the ten birds in this group developed the lesions characteristic of vitamin A deficiency and five (50 per cent) died of this cause. The average weight of the birds which survived to the end of the experiment was 1132 grams on October 16 and 1372 grams on Jan- uary 22, an increase in weight of 21.2 per cent during ninety-six days of experimental feeding. Nineteen eggs were produced by this group during the experiment. Group III — Basal ration plus Danvers Half Long carrot (red). The amount of Danvers Half Long carrot was maintained at one gram daily throughout the experiment. No lesions of nutritional disease appeared and no birds died from any cause. The average weight of the birds in this group on October 16 was 1056 grams and on January 22, the close of the experiment, was 1492 grams, an increase of 41.2 per cent in weight during ninety-six days of experimental feeding. Thirty-one eggs were produced in this pen before the birds were six months of age. The production from December 12, the day the birds were six months of age (the fifty-fifth day of the experiment) until the close of the experiment was 33.3 per cent. A total of 171 eggs was produced during the experiment. Group IV — Basal ration plus Golden Tankard mangel (yellow). The first lesions of nutritional disease in group IV appeared on November 20 (the thirty-third day) in bird 33. On November 27 (the fortieth day) lesions appeared in bird 31. The amount of mangel was increased to two grams daily on November 28. Bird 31 died of nutritional disease on November 30 (the forty-third day). By December 4 (the forty-seventh day) five new cases of nutritional disease (32, 35, 37, 38, and 40) had developed. The amount of mangel for this group was increased to eight grams daily on December 5. Bird 37 died of nutritional disease on December 8 (the fifty-first day) and bird 35 died on December 10 (the fifty-third day) from the same cause. One new case of nutritional disease (in bird 34) was found on December 11 (the fifty-fourth day). The amount of mangel was increased to sixteen grams daily on December 12. On December 18 (the sixty-first day) bird 36 showed pustules in the esophagus. With the exception of bird 39 all remaining birds in this group showed lesions in the esophagus. Bird 38 died of nutritional disease on December 23 (the sixty-sixth day). On December 25 the amount of 8 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION mangels was increased to thirty-two grams daily. Bird 33 died of nutritional disease on December 26 (the sixty-ninth day). Bird 40 died of nutritional disease on January 2 (the seventy-sixth day) and bird 32 died on January 5 (the seventy-ninth day). Pustules had developed in bird 39 on January 8 (the eighty-second day). Bird 36 died of nutritional disease January 18 (the ninety-second day). All of the birds in this group developed symptoms of vitamin A deficiency and eight died. The average weight of the birds that survived to the end of the experiment was 935 grams on October 16 and 1180 grams on Jan- uary 22, an increase of 26.2 per cent in weight during ninety-six days of experimental feeding. The birds in this group produced no eggs during the experiment. Group V — Basal ration plus White Belgian carrot. The amount of White Belgian carrot was maintained at one gram daily until November 27 (the fortieth day). Bird 43 showed pustules on this date and died on December 1 (the forty-fourth day). The amount of carrot was increased to two grams on November 28. Two more birds (42 and 49) showed nutritional disease lesions on Decem- ber 5 (the forty-seventh day) and the daily amount of carrot was increased to four grams. Bird 48 showed pustules on December 11 (the fifty-fourth day). On December 18 (the sixty-first day) two new cases, birds 44 and 46, developed. The amount of carrot was increased to eight grams on December 19. Bird 45 showed lesions on December 24 (the sixty-seventh day) and the carrot was increased to sixteen grams on the following day. Bird 42 died of nutritional disease December 25 (the sixty-eighth day). Since sixteen grams was more than the birds would voluntarily consume, the daily supply of carrot Avas not increased above this amount. Bird 44 died of nutritional disease on January 7 (the eighty-first day) and bird 49 died on January 13 (the eighty-seventh day) of the same cause. Pustules first appeared in birds 41 and 47 on January 8 and 15 (the eighty-second and eighty-ninth days), respectively. Four birds died of nutritional disease, five showed pustules at the close of the experiment and one was apparently in good health. The average weight of the birds that survived to the end of the experiment was 1148 grams on October 16 and 1460 grams on Jan- uary 22, an increase of 27.1 per cent in weight during ninety-six days of experimental feeding. This group produced sixteen eggs during the experiment. BUL. 412] A STUDY OF SOURCES OF VITAMIN A FOR POULTRY 9 Group VI — Basal ration plus Half Sugar mangel (white). The first indication of vitamin A deficiency in group VI was the appearance of pustules in birds 51 and 52 on November 20 (the thirty- third day). Bird 55 died of nutritional disease on November 27 (the fortieth da}^ without having previously shown symptoms of the disease. The amount of mangel was increased to two grams daily on November 28. On December 4 (the forty-seventh day) four more birds (53, 56, 57, and 60) show^ed pustules in the esophagus. The amount of mangel was increased to sixteen grams on December 12. Birds 51, 60, and 56 died of nutritional disease on December 12, 15, and 22 (the fifty-fifth, fifty-eighth, and sixty-fifth days), respectively. Bird 54 developed pustules and bird 52 ophthalmia on December 24 (the sixty-seventh day). The amount of mangels was increased to thirty-two grams daily on December 25. Birds 52 and 59 died of nutritional disease on December 30 (the seventy-third day). The first pustules in bird 59 were observed on December 24, six days before death. Bird 58, the last bird to develop lesions of vitamin A deficiency, show^ed pustules on December 31 (the seventy-fourth day). Bird 54 died of nutritional disease January 15 (the eighty-ninth day). All of the ten birds in this group developed nutritional disease and seven died from this cause. The average weight of the birds that survived to the end of the experiment was 1023 grams on October 16 and 1233 grams on Jan- uary 22, an increase of 20.5 per cent in weight during ninety-six days of experimental feeding. The total production from this group was three eggs. Group VII — Basal ration plus American Purple Top Swede turnip {yellow). The amount of American Purple Top Swede turnip was maintained at one gram daily until November 27 (the fortieth day) when it was increased to two grams because three birds (65, 66 and 67) showed pustules in the esophagus. The first pustules to appear in this group were in bird 65, on the thirty-third day. On November 27 bird ^^, which showed pustules, was destroyed by its mates. The amount of turnip was increased to four grams on December 5 (the forty-eighth day) when one new case, bird 63, developed. On December 7 bird 61 died. A post-mortem examination showed a slight congestion of urates in the kidneys, but there was not sufficient evidence to warrant a diagnosis of death due to nutritional disease. On December 16 (the fifty-ninth day) bird 65 died of nutritional disease and on December 18 (the sixty-first day) bird 70 died of the same cause. On December 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 18 birds 69 and 64 showed pustules. The amount of turnip was increased to eight grams on December 19. On December 31 bird 68 died of nutritional disease. The amount of turnip was increased to sixteen grams daily on January 1. Bird 64 died of nutritional disease on January 2 (the seventy-sixth day). On January 15 (the eighty-ninth day) bird 62, the last of this group, showed pustules. The amount of turnip was increased to thirty-two grams daily on January 16. Two birds in this group (61 and 66) died of causes other than nutritional disease, but one of these had the characteristic pustules in the esophagus. Nine of the ten birds in this group developed lesions of vitamin A deficiency and four died of this cause ; the four remaining birds showed pustules at the close of the experiment. The average weight of the birds that survived to the end of the experiment was 1130 grams on October 16 and 1147 grams on January 22, an increase of 1.5 per cent in weight during ninety-six days of experimental feeding. This group produced seven eggs during the experiment. Group VIII — Basal ratio7i plus Purple Top White Globe turnip. On December 7 bird 71 was destroyed by its mates. The first lesions of nutritional disease in group VIII appeared in two birds (74 and 75) on December 11 (the fifty-fourth day). Bird 75 died of nutritional disease on December 14 (the fifty-seventh day). Bird 73, which showed no evidence of vitamin A deficiency when examined on December 11, died of nutritional disease December 17 (the sixtieth day). The amount of turnip was increased to two grams daily on December 19. Bird 74 died of nutritional disease on December 26 (the sixty-ninth day). Bird 79 died December 30 (the seventy-third day) without having previously exhibited symptoms. The amount of turnip was increased on January 1 to four grams daily. Bird 80 showed pustules on January 8 (the eighty-second da}^). Birds 76 and 78 showed pustules on January 15 (the eighty-ninth day). The amount of turnip was increased to eight grams daily on January 16. On the ninety-sixth day lesions appeared in bird 77. One bird (71) in this group was destroyed by mates, four died of nutritional disease, four showed pustules at close of the experiment and one was apparently in good health. The number which suffered from nutritional disease was eight, or 80 per cent. The average weight of the birds that survived to the end of the experiment was 1012 grams on October 16 and 1250 grams on Jan- uary 22, an increase of 23.5 per cent in weight during ninety-six days of experimental feeding. This group produced 27 eggs during the experiment. BUL. 412] A STUDY OF SOURCES OF VITAMIN A FOR POULTRY 11 Group IX — Basal ration plus salmon oil. The amount of salmon oil was maintained at one cubic centimeter daily throughout the experiment and no lesions of nutritional disease appeared. One bird (95) died from ileal intussusception and chronic coccidiosis. The average weight in this group on October 16 was 999 grams and on January 22, at the close of the experiment, was 1444 grams, an increase of 44.5 per cent in weight during ninety-six days of experimental feeding. Twenty-eight eggs were produced in this pen before the birds were six months of age. The production from December 12, the day the birds were six months of age (the fifty-fifth day of the experiment) until the close of the experiment was 26.4 per cent. This group produced a total of 128 eggs during the experiment. A pen of ten birds to which mung bean {Phaseolus aureus) sprouts were given as a supplement to the basal ration was included at the beginning of the experiment. On account of difficulty in sprouting the seeds, the supply of sprouts was inconstant and no definite knowl- edge regarding their value was being secured. Therefore, after 67 days, the feeding of this supplement was abandoned and the daily administration of 1 cc. of salmon oil to each bird was substituted. At the time the change was made, growth and egg production of the birds had ceased and six of them had the lesions characteristic of vitamin A deficiency. During the following 28 days until the experi- ment was terminated, these birds entirely recovered from the effect of vitamin A deficiency, increased 13.1 per cent in weight and pro- duced 29 eggs. Group X — Basal ration. Controls. The first evidence of nutritional disease in group X was the death from this cause of bird 106 on November 19 (the thirty-second day). Pustules of nutritional disease appeared in bird 107 on November 27 (the fortieth day). Bird 108 died of nutritional disease December 2 (the forty-fifth day). Bird 109 showed pustules on December 4 (the forty-seventh day) and on December 11 (the fifty-fourth day) nutri- tional disease had appeared in birds 102 and 110. On December 18 (the sixty-first day) bird 101 developed pustules. Birds 107 and 109 died of nutritional disease on December 20 and 22 (the sixty-third and sixty-fifth days), respectively. Pustules appeared in bird 103 on December 24 (the sixty-seventh day). Bird 101 died of nutritional disease on December 27 (the seventieth day) of the same cause. Bird 12 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION i o ?1 J2 -gTJ 3; I a) S 03 o S ° aa-§ ■^ S as 2*0 g-t3 a o aa-^ o q 0000 (M l-t T-l O O >0 O 00 -^ t^ TjH Tj< O CO O Oi O O C5 o O (M C^ (M '-I »0 10 10 to t^ tB m m VI a s s s a c3 o3 oj o3 oj fcH t-l t-l ^ ?H S-l bC bC bC fc>C faC bO oi a a ;h ;h o faC faC a a a a a a a c3 c5 o3 c3 c3 o3 ;_ ^ ^H !-< M !h biD bC bC bC bJO bJO a a bJ3 bi) O ■Si 't3 0^ IS ^ 2 Z. S s^ a; " 03 bJO ^a o3 a §2 o3 O •■^ ^ 2 ^ g bfl^ I a,^ bC sh Ph (Ti ^S rt j5 03 a ^ M '-2 S T3 8 1^ « a g ^ i 3 t- « !> O -d •^ T3 M •-< X2 01 a; w o o o BUL. 412] A STUDY OF SOURCES OF VITAMIN A FOR POULTRY 13 105 showed pustules in the esophagus January 8 (the eighty-second day) and lesions appeared January 15 (the eighty-ninth day) in bird 104, the last bird of the group. The average weight of the birds which survived to the end of the experiment was 1040 grams on October 16 and 1297 grams on Jan- uary 22, an increase of 24.7 per cent in weight during the ninety-six days of the experiment. All of the ten birds in this group became affected with nutritional disease and six (60 per cent) died from this cause. This group produced only two eggs during the experiment. A tabulated summary of results is given in table 2. DISCUSSION OF THE EXPERIMENT None of the birds in groups I, III, and IX that received yellow carrots, red carrots, and salmon oil, respectively, showed any evidence of vitamin A deficiency during the experiment. One bird in group IX died from ileal intussusception and upon autopsy was found also to be affected with chronic coccidiosis. All three of these groups increased in weight from 41 to 44.5 per cent. The egg production for the last forty-one days was 30.4 per cent in group I, 33.3 per cent in group III and 26.4 per cent in group IX. The curative value of salmon oil for fowls suffering from vitamin A deficiency was demonstrated by its effect on the group to which mung bean sprouts had been fed. Six birds which had developed symptoms of vitamin A deficiency recovered, and all of the ten birds in the group increased in weight and egg production after salmon oil was substituted for the sprouts. The results obtained with White Belgian carrots (group V) were decidedly inferior to those obtained with either red or yellow carrots. Increasing the amount of white carrots to sixteen grams for each bird daily did not prevent the development of symptoms of vitamin A deficiency. This group showed a 27.1 per cent gain in weight as compared with a gain of 42 and 41.2 per cent gain respectively in groups I and III, which received yellow or red carrots. Ten eggs were produced after these birds were six months of age while during the same period group I laid 128 eggs and group III laid 140. Both varieties of turnips used proved to be poor sources of vita- min A. Although 40 per cent of the birds in each group died of nutritional disease and there was a variation of only 10 per cent in 14 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION the number of birds showing lesions in each group (90 per cent in group VII and 80 per cent in group VIII) there was a marked difference in the results obtained with these two varieties as was indicated by a difference in the time of appearance of the first lesions, the gain in weight, and the egg production of the two groups. The first lesions of nutritional disease appeared in group VII (American Purple Top Swede turnip) on the thirty-third day and in group VIII (Purple Top White Globe turnip) on the fifty-fourth day, twenty-one days later. Group VII increased 1.5 per cent in weight and produced a total of seven eggs, while group VIII increased 23.5 per cent in weight and produced a total of twenty-seven eggs. The fact that the amount of American Purple Top Swede turnip supplied was increased to thirty-two grams daily while in group VIII the maximum daily amount of Purple Top White Globe turnip was eight grams, further emphasizes the difference between these two supplements. All three varieties of mangel beets used proved valueless as sources of vitamin A. There were slight differences between the three groups with respect to the time of the first appearance of lesions, the mor- tality, increase in weight, and the egg production, but all the birds in these groups developed definite lesions of vitamin A deficiency. The amount of these supplements was increased to thirty-two grams daily, which was more than the birds would voluntarily con- sume. Following this increase, there was no improvement in the condition of the birds already affected and nutritional disease lesions developed in all those apparently healthy at the time the increase was made. All birds in group X (control) developed nutritional disease and 60 per cent died of this cause. BUL. 412] A STUDY OF SOURCES OF VITAMIN A FOR POULTRY 15 h^,^ CONCLUSIONS It is recognized that the number of birds used in this experiment was small, but nevertheless the results are so clear-cut that the follow- ing definite conclusions may be drawn: (1) The Yellow Giant carrot and Danvers Half Long carrot (red) are equal in value to the commonly used varieties of green feed^^ as sources of vitamin A for poultry. (2) The salmon oil appears to be as good a source of vitamin A for poultry as yellow carrots, red carrots, or the commonly used varieties of green feed. The salmon oil used also appears to compare favorably with cod-liver oil as a source of vitamin A for poultry, since the amount used in this experiment is the same as that of cod-liver oil used in previous experiments^^ and as is commonly recommended to supply vitamin A in poultry rations. (3) The Purple Top White Globe turnip appears to contain some vitamin A, but is not a sufficiently good source to make it of any practical value in poultry feeding. (4) The White Belgian carrot, American Purple Top Swede urmp (.(s^htt^ , Mammoth Long Red mangel. Golden Tankard mangel (yellow), and Half Sugar mangel (white) are of no value as sources of vitamin A for poultry. 11 Based on Davis, D. E,, and J. E, Beach, op. cit. 12 Beach, J. E., op. cit., p. 4.