Digesta flow studies in sheep fed two mature annual legumes

Abstract

Mature subterranean clover (Trifolium subterraneum cv. Junee) and Persian clover (Trifolium resupinatum cv. Kyambro) were fed to cannulated sheep. Flow rates of dry matter and nitrogen in the abomasum and ileum were estimated using a double marker method. Contents of hemicellulosic polysaccharides (xylose and mannose monomers) were higher in Kyambro than in Junee. Although Junee contained higher levels of total N and amino acids, the relative concentrations of cystine and methionine were markedly higher in Kyambro. Dry matter intakes and flow rates in the abomasum, ileum and faeces were similar on Kyambro and Junee. Dietary nitrogen intake was lower and endogenous re-cycled nitrogen higher on Kyambro than on Junee. Ileal flow of nitrogen was similar to nitrogen intake on Kyambro. Apparent nitrogen digestibility was lower in the whole tract and higher in the intestines on Kyambro. The higher apparent digestibility of nitrogen in the intestines of sheep eating Kyambro was associated with a greater proportion of nitrogen leaving the stomach coming from endogenous sources. The lower nitrogen digestibility of Kyambro in the whole tract indicated lower digestibility of dietary nitrogen, which was associated with higher contents of xylose and mannose.