The synthesis of vitamins in the rumen of sheep. II. Levels of thiamine, riboflavin, and nicotinic acid in the rumen of grazing lambs

Abstract

The thiamine, riboflavin, and nicotinic acid levels were measured in ewes' milk and herbage, and in the rumen contents of young lambs being reared on these foods. The vitamin levels in the rumen contents increased sharply during the first 3 weeks of the lamb's life but thereafter showed no change with age up to 9½ weeks of age. The lambs were weaned at 8 weeks of age, and after weaning there was less variability in the rumen levels of all vitamins, and the levels of nicotinic acid were lower than before. The possible significance of these observations in relation to the existence of microbial synthesis of vitamins in the rumens of suckling lambs is discussed.