Carotene and Vitamin A Requirements for White Leghorn Chicks

Abstract

The minimum vitamin A requirement of the chick is relatively high per pound of body weight as compared to the rat. The minimum requirement of vitamin A of the White Leghorn chick at the age of about 8 weeks is approximately 65 A.D.M.A. units per day. Results were obtained by comparing the average number of days lived per chick in relation to the number of units of vitamin A supplement received as compared to the average of the control group. Chicks offer interesting possibilities as test animals for vitamin A. No cases of ‘slipped tendon’ were observed in 792 White Leghorn chicks depleted in vitamin A, but given a diet adequate in other respects. Practically all of the 792 chicks depleted in vitamin A showed marked ataxia 3 to 14 days before complete depletion and death, even though given an adequate amount of vitamin D. This suggests the undesirability of using the broad term ‘leg weakness’ as related to vitamin D deficiency. There is a wide variation in the number of days chicks will live on a vitamin A-free diet, no doubt due to variation in storage from the egg from which the chicks hatched, which in turn was dependent on the storage or ration of the parent fowl. The addition of carotene or vitamin A to the carotene and vitamin A-free ration delayed the appearance of deficiency symptoms and prolonged life in a rather definite relation to the amount of carotene or vitamin A added to the diet.