Nov., 1938] Vitamin A Requirements of Growing Chicks 5 



the first four weeks or the first eight weeks, according to respective lot, 

 the regular reserve ration and were then changed to the vitamin A de- 

 ficient or control ration. The object was to determine the effect on 

 growth of previously stored up vitamin A, if any, when the ration was 

 later changed to a deficiency basis. 



The basal or control ration consisted of 140 pounds wheat bran, 140 

 pounds ground oat groats and 70 pounds of meat scrap. The reserve 

 ration was the regular New England College Conference ration as rec- 

 ommended for starting and growing chicks and consisted of 200 pounds 

 coarse yellow corn meal, 100 pounds wheat bran, 100 pounds wheat flour 

 middlings, 100 pounds ground oats, 50 pounds meat scraps (50% protein), 

 25 pounds fish meal (at least 50% protein), 50 pounds dried skim milk, 

 25 pounds alfalfa leaf meal, 15 pounds calcium carbonate, 5 pounds salt 

 and 1% of cod liver oil. 



The records taken during the period covered (1) individual weight and 

 gain figures weekly, (2) feed consumption weekly, (3) mortality, (4) 

 microscopic examination of feces from each group and an autopsy regu- 

 larly of one specimen of each group, (5) photographs of live specimens 

 of each group, and (6) photographs of kidneys of these representative 

 specimens. The tibia and femur bones of each bird so photographed 

 were saved for a check on condition of calcification. 



Discussion 



In the analysis of the enclosed tables we find some very interesting 

 data. In Table I, which shows the average weight per chick for each 

 week in the several groups, we find that at sixteen weeks the reserve 

 group was leading with a weight of 4.211 pounds per chick. The group 

 on basal ration plus 3% cod liver oil was in second place with an average 

 weight per chick of 4.031 pounds. The group weighing the least at the 

 end of this period was the 1% cod liver oil group with an average weight 

 per chick of 3.713 pounds. 



If we study this table on the basis of twelve weeks, we find the reserve 

 group again in the lead with an average weight per chick of 3.126 pounds. 

 The 3% cod liver oil group again is second with an average weight per 

 chick of 2.895 pounds. The lowest weight group, disregarding control 

 groups, is the 5% cod liver oil group with an average weight of 2.627 

 pounds. 



Then considering average weights from a basis of eight weeks, we note 

 the same relation with the reserve group leading, the 3% cod liver oil 

 group in second place and the 5% cod liver oil group the lowest in weight 

 per chick. At the end of the four- week period the 1% cod liver oil group 

 takes first place instead of the reserve group and the 5% cod liver oil 

 group is again last. 



With these placings in mind, two factors at once appear evident. First 

 of all, since the group on the regular reserve ration led all others in 

 growth for the sixteen- week period, it appears that vitamin A should be 

 supplied through other sources besides cod liver oil alone. Secondly, 

 there appears to be a definite requirement of vitamin A necessary for 

 proper growth and nutrition as evidenced during this sixteen-week ex- 

 perimental period. In explanation of this last statement, notice in Table 



