Enzyme Additives For Nonruminant Animals

In the nonruminant diet, enzymes are used more as a feed treatment than as a supplement. Their purpose, principally, is to degrade indigestible or antinutritional factors (such as protease inhibitors) within the feed, to improve digestibility of poor-quality feed, or to remove inhibitors of digestion. Improvements to health are brought about by the removal of these antinutrients and by rendering poorly digestible carbohydrates into a form that is digested in the ileum, resulting in a reduction in fermentable substrate entering the large intestine. Although the enzyme may be added to the feed rather than applied as a pretreatment, the principle is the same. The enzymes act on components of the feed, not on the digestive processes of the animal or on its microflora.

Nonstarch polysaccharides (NSP), such as xylans and glucans in poultry feeds, can cause poor digestibility, resulting in sticky litter and hock burn in the birds. These problems have been successfully treated with xylanases and glucanases in the feed.[6] In pigs, the hexose-based NSP (glucans) are broken down by microbial action in the small intestine and therefore do not cause problems, although xylans can pass undigested into the large intestine. Wheat-based diets contain proportionately higher quantities of pentosan-based NSP such as xylan, and supplementation of these diets with xylanases is associated with a reduced incidence of nonspecific colitis in pigs. There are few problems associated with barleybased diets for pigs, and enzyme supplementation shows little improvement in the pigs on these diets.

Further applications include the use of phytases to increase the availability of phosphorus in the diet and the removal of protease inhibitors, particularly in high-soya diets. To date, enzymes are much more widely used in poultry than in pig diets, although their application for pigs is increasing.

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