The digestion of the lipids of processed red clover herbage by sheep

Abstract

Abstract Three mature wether sheep, equipped with re‐entrant cannulae at the proximal duodenum and terminal ileum were fed either frozen, or dried and chopped or dried and ground red clover herbage, and samples of duodenal and ileal digesta and faeces were collected. Analysis of the feed and digesta samples for their individual long chain fatty acid content enabled the quantitative digestion of herbage lipids to be investigated. The flow of total fatty acids into the small intestine was greater than the amount daily consumed when the dried diets were fed, whilst on the frozen diet there was a net loss between mouth and duodenum ( P <0.01). There was a marked increase in the proportion of saturated fatty acids in the fatty acid fraction collected at the duodenum relative to the feed on all diets, but some dietary differences were noted. The extent of hydrogenation was reduced on the ground diet and, to a lesser degree, on the chopped diet. Consequently these diets had significantly higher proportions of C18:1 in the duodenal fatty acid fraction than the frozen diet (ground, 22.5%; chopped 17.0, frozen 13.5; P <0.01). These changes influenced the quantity and composition of the fatty acid fraction absorbed from the small intestine; the ratio of unsaturated to saturated fatty acids absorbed (ground, 0.47; chopped, 0.32; frozen, 0.24) being significantly greater on the ground diet ( P <0.01).