Nov., 1938] Vitamin A Requirements of Growing Chicks 



21 



by Guilbert. Acknowledgement, is made of the service of C. K. Shuman, 

 graduate assistant in agricultural chemistry, for his services in the chem- 



PtiUf^ds 



Experiment F, com- 

 parative growth chart. 

 1936-37. 



ical determination of vitamin A and the preparation of solutions. We 

 wish also to acknowledge the courtesy of Purina Mills for supplying the 

 carotene concentrate. 



The vitamin A concentrate was incorporated in Wesson oil in a homo- 

 geneous mass to provide solutions having a potency of 48, 98 and 158 in- 

 ternational units per .4 cc. These solutions were then incorporated 

 within the basal ration to provide 134.4, 274.4 and 442.4 international 

 units per 100 grams of total feed. Feed was mixed fresh each week and 

 kept in tightly sealed containers. 



The basal ration consisted of 46 pounds ground white corn, 20 pounds 

 ground wheat, 5 pounds wheat bran, 15 pounds dried skimmilk, 10 pounds 

 meat scrap, 1 pound salt, 2 pounds calcium carbonate, and 1 pound ir- 

 radiated yeast (400,000 U.S. P. units per pound.) The control group re- 

 ceived basal ration only, with no addition of vitamin A. 



All chicks were maintained in individual cages, developed at this 

 station, throughout a period of 42 days. Daily weight and feed consump- 

 tion records were kept for all individual chicks. 



Discussion 



The average gro\Hh curves for each lot are presented in diagrammatic 

 form. It will be noted that the growth of groups 2 and 3, receiving 134.4 

 and 274.4 international units per 100 grams of feed, very closely parallel 

 each other. The final weight at 42 days of age was substantially the 

 same. Group 4 receving 442.4 int. units per 100 grams of feed paralleled 

 the other curves up to approximately the 34th day when more rapid 

 weight gains become evident. This action seems to indicate that there 



