Effect of Pregnancy and Lactation on Liver Vitamin A of Beef Cows Grazing Pangolagrass

Abstract

The effect of pregnancy and lactation on vitamin A and carotene in liver and plasma was determined for beef cows grazing pangolagrass. The cows averaged 13.4 years of age and had grazed pangolagrass continuously as the only source of nutrients for an average of 9.5 years. Calves were weaned August 29, 1965, and cows were slaughtered December 8, 1965. Ten cows, nursing calves in 1965 and pregnant when slaughtered, had an average of 12.3 million I. U. equivalent vitamin A in liver and plasma; seven cows, dry in 1965 and pregnant, had 20.9 million I. U.; three cows, nursing calves in 1965 and open, had 13.3 million I. U.; and one cow, dry in 1965 and open, had 24 million I. U. vitamin A. A well managed pangolagrass pasture in southcentral Florida furnished adequate carotene to meet the vitamin A needs of producing beef cows.