Effect of Hepatic Vitamin A and Carotene Concentration on the Biological Value of Carotene in the Bovine

¹ From the Department of Animal Science, University of Arizona, Tucson, Arizona

Steers were individually fed varying amounts of carotene in accord to body weight for 110 days. Hepatic carotene retention did not prove to be indicative of carotene intake. While 7.54 mg of dietary carotene was necessary to maintain initial hepatic vitamin A content, liver vitamin A storage was not a linear function of the amount of carotene consumed. All animals were then fed similar amounts of carotene based on body weight. While vitamin A retention was related to previous carotene intake as well as the initial liver vitamin A content, hepatic carotene retention was related only to the initial liver carotene content. In a second study, heifers were pretreated with varying amounts of preformed vitamin A and fed a carotene-vitamin A free ration for 61 days. The initial liver concentration of vitamin A greatly influenced the magnitude of liver vitamin A expenditure. However, all animals lost a similar percentage of their initial hepatic vitamin A content.