The development of ruminant digestion in the calf. II.* The digestion of barley and urea

Abstract

Two Friesian calves were fitted with re-entrant cannulae in the duodenum and four Friesian calves were fitted with re-entrant cannulae in the duodenum and terminal ileum within 1 week of birth. At 35 days of age the calves were weaned from milk and offered a diet containing 72% barley, 3.5% urea and 15 % wheat chaff. Total collections of digesta flowing from the duodenum and ileum were made for 12 hr at weekly intervals for 6 weeks after weaning. Of the dry matter ingested, 26% was apparently digested in the stomach 1 week after weaning, 40% by 2 weeks after weaning and increasing to 51% by 6 weeks after weaning. The flow of nitrogen to the duodenum was greater than the nitrogen intake in the first week after weaning, and it gradually decreased to 83% of the nitrogen intake by 6 weeks after weaning. During this period the contribution of microbial nitrogen to the nitrogen flow increased from 28 to 71%. The apparent absorption of amino acids from the small intestine increased with increasing feed intake, but the uptake of methionine was less than the methionine requirement for growth. _________________
* Part I, Aust. J. Agric. Res., 26: 1081 (1975).