Nov., 1938] Vitamin A Requirements of Growing Chicks 7 



I that the control group receiving no vitamin A was in the lead up to 

 the third week. The lead was then taken by the 1% cod liver oil 

 group and held until the fifth week when the 2% cod liver oil group was 

 in the lead. At eight weeks the 3% cod liver oil group took the lead 

 and held it until the end of the experimental period. 



EXPERIMENT A, TABLE II, Leading groups according to weekly periods and 



their estimated vitamin A consumption 



In way of explanation for the poor start of the reserve group, it should 

 be said that a serious slip in brooding management was encountered and 

 twelve chicks were lost the first week. This we believe to be the cause 

 of the poor weight records for the first four weeks for this group. 



In reference to the three control groups we note that the group which 

 was started on a vitamin-deficient ration made good growth for two 

 weeks, but from then on very poor gains were made and throughout the 

 remaining twelve weeks it was the poorest group. At the age of four 

 weeks this group showed evidence of weakness in its ability to stand and 

 walk properly. Ruffed feathers also were apparent at this age. 



The control group taken from the reserves at four weeks did well on 

 the deficient ration for the first week only. After that it started to slide 

 backwards and at twelve weeks was far behind the reserve group. In 

 conjunction with this it was noticed that the yellow pigment disappeared 

 after one week on the control ration. 



With the 8-12 week control group similar effects were noticed. Not 

 one week of their existence did they make as great a gain in weight per 

 chick as did the reserve group. After three weeks on the vitamin A de- 

 ficient ration, the yellow pigment disappeared. 



From the actions of these three groups it appears that the baby chick 

 absorbs enough vitamin A in the yolk at hatching time to fulfill its re- 

 quirements for about two weeks. It also appears evident that there is 

 a slight storage of vitamin A but not enough to fulfill the chick's require- 

 ments, as evidenced by the actions of the 4-12 and 8-12 week control 

 groups as compared to that of the reserve group. Since the control group 

 made good gains up to the third week; the 4-12 week control made a 

 good gain for one week after being placed on a vitamin A deficient ration; 

 and the 8-12 week control group did not gain so well as the reserve group 

 during its existence — these facts are additional foundation for our pre- 

 vious statement, that there is a definite requirement for vitamin A as the 

 chick's age increases. (Refer to Experiment E.) 



Table I also presents the total feed consumption per chick for the entire 

 experimental period. There appears to be very little difference in total 

 feed consumption in the various groups receiving the basal ration plus 



