Some Experiments on the Physiology of Vitamin A Storage in the Chick

IN A previous paper (Rubin et al., 1941) evidence was presented that border-line vitamin A deficiency, as indicated by liver storage assays, is quite common among chicks raised on commercial poultry farms. These experiments were based on the supposition that liver storage of vitamin A is directly related to intake. However, the possibility of other factors influencing vitamin A storage was not excluded, and the experiments to be reported in this paper were undertaken to investigate some of the more likely possibilities. In the first place, it seemed worthwhile to determine the comparative efficiency of vitamin A storage in the liver when carotene is the sole source of vitamin A potency and when vitamin A is supplied as such. Since it has been reported that carotene is more stable in mixed feeds than is vitamin A (Fraps and Kemmerer, 1937), it seemed quite possible that some chicks in commercial flocks . . .