The hydrolysis by rumen and caecal microbial enzymes of hemicellulose in plant and digesta particles

Abstract

Summary:In sheep fed red clover hay nearly 40% of the feed hemicellulose left the rumen undigested and scarcely any of this hemicellulose was digested in the postruminal digestive tract. The caecal microflora from sheep fed the same diet did, however, yield enzyme extracts which readily hydrolysed isolated hemicellulose or xylan preparations. These caecal and rumen microbial extracts, were capable of hydrolysing the hemicellulose in undigested particulate plant material but were not capable of hydrolysing, to any extent, the hemicellulose in undelignified digesta particles from various parts of the postruminal digestive tract. The hemicellulose in delignified postruminal digesta and the hemicellulose polysaccharides isolated from the digesta were hydrolysed by both rumen and caecal hemicellulases. The results are discussed in the light of observations on the postruminal digestion of hemicellulosic material in roughage- and cerealfed animals.