Utility of fiber degrading enzymes in improving utilization of fiber fractions in corn distillers dried grains with solubles and wheat middling in pigs: in-vitro and in-vivo approaches

Corn distillers dried grains with solubles (DDGS) and wheat middling (WM) are commonly used in swine diets, however, the high fiber content negatively influences their nutrient availability and growth performance in pigs. Supplemental fiber degrading enzymes (FDE) have been used to improve utilization of fibrous ingredients for pigs, however, results have been inconsistent due to various reasons. It is imperative to match enzyme activity with target substrates. Moreover, substrates exist in complex relationships with other components suggesting the need for combined activities. Herein are three experiments that examined effectiveness of FDE (mix of xylanase, β-glucanase and cellulase) on fiber fractions in corn DDGS and WM. In experiment 1, FDE was applied alone or with protease on DDGS or WM in vitro. FDE resulted in greater fiber hydrolysis and monosaccharide release, however, there were no effects of protease. Therefore, in experiment 2, digesta was collected from the terminal ileum of growing pigs fed DDGS or WM diets to determine whether FDE or single xylanase can hydrolyze undigested fiber fractions. FDE was more effective in releasing monosaccharide than xylanase as illustrated by an increased fiber hydrolysis. Lastly, in experiment 3, FDE was added in corn plus DDGS or wheat plus WM diets and fed to growing pigs. FDE improved growth performance linked to improved fiber digestibility and modulation of gastrointestinal morphology. In conclusion, FDE improved fiber hydrolysis under in vitro, in vivo- in vitro, and in vivo conditions. The addition of protease did not increase the fiber degradation further and FDE was more effective than single xylanase. The improvement seen in in vitro studies resulted in improved animal performance.