Rate of Absorption of Carotene and of Vitamin A from the Alimentary Tract of Dairy Calves. II. Effects of Methods of Dispersion and of Administration

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Abstract
Vitamin A (in an oily menstrum, an homogenized emulsion and an aqueous dispersion) and carotenoids (in an oily solution and an emulsion) were mixed in a filled milk and fed via nipple. Vitamin A supplements (as an oily medium and an aqueous dispersion) in milk also were administered by stomach tube. Rate of administration was 1000 IU/lb. body weight. Changes in concentrations of vitamin A and of carotenoids in blood plasma, during a 15-hour period after administration, were the criteria of absorption. Concentrations of vitamin A in blood plasma increased and subsequently decreased more rapidly than did those of carotenoids. Emulsification of the oily supplements in milk by homo-genization significantly enhanced the apparent absorption of carotenoids but did not improve markedly the absorption of vitamin A. Aqueous dispersion of vitamin A effected more rapid passage into the blood and a higher maximum level than did either the emulsion or the oily solution. Ingestion of vitamin A by nipple resulted in more rapid absorption and higher concentration in the plasma than did administration by stomach tube.

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