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Elevation of Plasma Carotenoids by Vitamin A Administration in the Bovine¹

Department of Animal Science, University of Arizona, Tucson

ABSTRACT

Considerable research has been concerned with factors that alter plasma carotene concentration in the bovine. Several workers, including Braun (1), have presented results which indicate relationships between plasma carotene and vitamin A when a carotene source is fed. For the most part, massive vitamin A doses have tended to depress the content of carotene in the plasma. However, the physiological importance of circulating carotene has been questioned since Church et al. (2) showed that beef calves did not convert intravenously injected carotene to vitamin A.

These studies were conducted to supplement previous findings relating to plasma carotene alterations resulting from vitamin A administration.

Study A. Twenty yearling Angus heifers were divided into five equal groups and adjusted to a carotene—vitamin A-free experimental ration for seven days. Five sources of vitamin A were orally administered by capsule in accordance with body weight (1,000 I.U. per pound): (a) crystalline vitamin A acetate emulsion in Tween 80 and water, (b) water-dispersible fish oil², (c) gelatin-coated vitamin A³, (d) wax-micratized vitamin A⁴, and (e) water-dispersible dry vitamin A².

¹ Arizona Agricultural Experiment Station Technical Paper No. 480. The authors appreciate the cooperation, of the following companies in supplying their vitamin A products: