Improvement of Nutritional Value of Wheat by Dietary Enzyme Supplementation for Turkeys.

Abstract

The increasing world production of turkeys and broilers is increasing the demand for wheat as a major feedstuff. Wheat and wheat-by products vary in apparent metabolizable energy (AME) content due to the presence of non-starch polysaccharides (NSP). Enzymes have become an important dietary supplement to improve nutrient utilization and growth performance of poultry fed NSP-rich diets. This study explored the use of dietary enzyme supplementation to improve the nutritional value of inferior quality wheat for turkeys. The first research trial compared the nutritional value of frost-damaged and normal-mature wheat fed to turkeys and how a blend of NSP degrading enzymes with major endoxylanase activity influenced their nutritive value. Day-old toms were raised up to 17 days of age. Growth performance, nitrogen-corrected apparent metabolizable energy (AMEn), nitrogen retention (%NR), and viscosity were measured. The second trial evaluated the effect of three different supplemental enzymes on the growth performance and energy utilization on turkeys fed inferior-quality of wheat. The three enzyme preparations used included a natural enzyme blend of endoxylanase and other enzymes, an enzyme with predominantly endoxylanase activity, and an enzyme with predominantly phospholipase activity. Day-old toms were raised up to 18 weeks of age. Growth performance, caked litter accumulation, AMEn, and viscosity were measured.

The supplementation of enzymes improved the nutritional value of wheat-based diets to a level similar to diets containing corn in place of wheat. The first study showed that frost damage during seed development significantly reduced the nutrient utilization of wheat, by presumably decreasing starch content and increasing the relative content of NSP. Supplementation of the enzyme improved the growth performance of turkey poults, regardless of the degree of frost damage of the wheat in the diet. In the second study, growth performance and energy utilization of turkeys fed diets containing a low AME wheat was significantly enhanced by phospholipase supplementation of starter feeds, while endoxylanase supplementation was most beneficial in growing and finishing feeds. Evidently, phospholipase alleviated the adverse effect of dietary NSP by improving fat digestion and absorption in young turkeys, whereas endoxylanase was more effective in older birds that have greater digestive capacity and more mature gut microbial ecosystem. Dietary supplementation of a natural blend of enzymes containing endoxylanase and other enzyme activities was beneficial for turkeys fed the wheat-based diet, regardless of the age of turkeys.

In conclusion, enzyme supplementation had positive effects on nutrient utilization of different wheat sources and cultivation conditions. Different sources of supplemental enzymes had variable effects according to the age of the birds. In general this research demonstrated that supplementation of appropriate enzymes is an effective way of dealing with grains with high NSP content in poultry diets.