EXOGENOUS ENZYMES FOR PIGS AND POULTRY

Many feed ingredients in use in monogastric diets contain significant quantities of antinutritional factors (ANF) which limit both their fee d value and their use. Almost all enzymes currently being used address such factors to varying degrees, allowing for more economic utilizati on of raw materials. However, animal response to xylanase, beta-glucan ase and even phytase utilization reported in the literature tends to v ary. Factors such as enzyme source, ingredient variety and environment under which the ingredient was grown, stored and processed into anima l feed, age of animal, interaction with other dietary ingredients, and health status are shown to affect significantly the response obtained . As a result, the mode of action of xylanases and beta-glucanases is still debated due to too much emphasis being placed on interpretation of individual trial results without regard to the interactive factors or the literature dataset as a whole. Better understanding of such fac tors will improve data interpretation. While results with phytase are not subject to such extreme variation, they are nevertheless inconsist ent in the degree to which inorganic phosphorus can be replaced by thi s enzyme. Greater understanding of the ANF and factors which interact to govern the response to added exogenous enzymes will undoubtedly imp rove the economic return and confidence in their use. Improved knowled ge of ANF structure will result in development of enzymes directed tow ards far more specific targets, which enhances the likelihood of succe ss and should reduce the overall enzyme usage.