The Absorption and Retention of Carotene and Vitamin A by Hens on Normal and Low Fat Rations

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Abstract
In hens the absorption of carotene in the crystalline form is improved by the presence of fat in the ration. On the low fat ration, and presumably on the normal, there appears in the excreta a yellow pigment which has the solubility properties of carotene, but which, according to spectrophotometric determination, is not a member of the carotene group of pigments. Neither carotene nor vitamin A is eliminated from the body stores by way of either the kidney or the intestine. Absorption of vitamin A by hens was essentially the same on normal and low fat rations. The length of the depletion period, prior to feeding vitamin A, had no effect upon the percentage of the factor absorbed. As the feeding levels were increased, the percentage of the factor excreted remained essentially the same in both groups and was characteristic of the individual hen. The presence of a small quantity of fat as the vehicle for vitamin A ester (1 mg. per 200 units) may have favored absorption. The retention of vitamin A in the liver was greater in the hens which received the ration with normal fat content.