Utilization of exogenous fibrolytic enzymes in ruminant feeding

Abstract

Added fibrolytic enzymes (e.g. cellulases, xylanases) to diets for ruminants have been viewed with considerable skepticism for years. Despite the considerable number of studies conducted recently, the mechanisms by which fibrolytic enzymes could improve fiber digestion in the rumen have not been clearly elucidated and seem to be affected by several factors such as the type of enzyme and the nature of the substrate. Inconsistent responses are thought to be due in part to differences in physical and chemical conditions under which the enzymes have been evaluated; for example, several studies showed that the highest activity of carbohydrate degrading enzymes was at pH from 3 to 7 for ß-glucanase and from 6 to 7 for xylanase. It suggests that these enzymes seem to work better at close to neutral ruminal pH conditions. In this chapter, we review some of the most relevant aspects about exogenous fibrolytic enzymes and its important influence over ruminant nutrition.