22 X. H. Agr. Experiment Station [Bulletin 310 



is an additional demand by the chicks for vitamin A after the first five- 

 week period. When this demand is met, more rapid and increased gains 

 in weight will result. 



The suggestion is here advanced that for rapid growth chicks with a 

 normal storage of vitamin A upon hatching need during the first five- 

 week jieriod a total intake of approximately 134.4 international units of 

 vitamin A per 100 grams of feed. Following this initial growth period 

 the demands for vitamin A are increased to approximately 400 units per 

 100 grams of feed. Inasmuch as the experimental period extended only 

 to 42 days, the limits of this second "demand" period are unknown. It 

 seems logical to assume that other "increased demand periods" do exist as 

 maturity increases. Sherwood and Fraps^"* state that fowls receiving the 

 higher amounts of vitamin A (444 units) showed a larger weight, the dif- 

 ferences appearing after the fourth month, indicating that stores of the 

 vitamin A in the bodies of the fowls fed the smaller amounts (224 and 

 336 units) were beginning to be exhausted by that time. 



The only mortalitj^ experienced during the experimental period occurred 

 in the control group receiving the vitamin A deficient basal ration. The 

 highest average weight recorded for the group was .40 pounds which oc- 

 curred at 23 days of age. The growth of the "control" chicks closely 

 paralleled that of the other groups up to ten days of age. After this 

 period the depletion of vitamin A originally stored in the body of the 

 chick was evidenced in less rapid growth. The occurrence of death of 

 chicks in the control group is shown on curve by a small circle. Death 

 in the control lot occurred at 21, 24, 32 and 39 days of age, respectively. 



The results of this year's work were in harmony with those of the pre- 

 vious year's work except for one primary fact. Chicks receiving 508 

 U.S.P.X. units (1935-36) showed a reduction of weight gains following 

 the fifth week. The work of this year was contradictory to this result 

 inasmuch as the highest vitamin A unit fed group (442.4 int. units) 

 showed increased gains after this period. To make for more exact trends 

 and greater elimination of experimental error it is deemed necessary to 

 materially increase the numbers of experimental birds in the various 

 groups. 



General Summary 



1. The requirement for vitamin A by growing chicks is relatively 

 large and becomes greater as maturity progresses. 



2. The supply of vitamin A in the chick ration shouhl ]irefcrably be 

 from more than one source. 



3. While there is some storage of vitamin A by chicks fed a well bal- 

 anced feed, there is not enough stored to meet their requirements during 

 a subsequent deficiency period of more than two weeks. 



4. Too high a content of cod liver oil in feed will tend to decrease 

 livability of chicks. 



5. Kidney injur>' and presence of urinary cr>'stals in feces and scrap- 

 ings of large intestine accomi)anies vitaminosis A. 



6. The feeding of increasing levels of vitamin A through periodic in- 

 creases in jier cent of cod liver oil is not warranted, providing the ration 

 contains at least 1% cod liver oil of a potency of 2,000 vitamin A units 

 per gratn. 



