Net transfer of nutrients to duodenum, and disappearance of n-alkanes in the reticulo-rumen and the hindgut of sheep fed grass/legume combinations
Four ewes were fed different proportions of lucerne (Medicago sativa) and Wimmera ryegrass (Lolium rigidum) (100:0, 33:67, 67:33 and 0:100), following a latin square design, to study the influence of the diet on the net transfer of nutrients to the intestines, and on duodenal and faecal recoveries of n-alkanes. Duodenal flows of dry matter, organic matter, neutral detergent fibre, non-ammonia nitrogen (NAN) and microbial nitrogen, and the efficiency of microbial synthesis, were not affected by diet, although the microbial contribution to the duodenal flow of nitrogen, and the ratio NAN/N intake were affected. Duodenal recovery of n-alkanes was not affected by diet, and was complete for those present in higher concentrations in the diets. Isolated rumen bacteria contained significant amounts of n-alkanes, contributing to their duodenal flow in variable proportions depending on the diet consumed. The mechanisms of and the reasons for this incorporation are unknown. The faecal recovery of the n-alkanes was affected by diet only in some cases.
Keywordsn-alkanes duodenum nutrients rumen bacteria sheep
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