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Interpretive Summary: The impacts of xylanase on the fermentability and digestibility of high insoluble fiber diets in growing pigs

By: Anne Kamiya, MS

Adding coproducts to swine feed is an economical choice that can also adversely impact the digestibility of feed. Coproducts contain a higher amount of non-starch polysaccharides (NSP), which cannot be digested by pigs. Poorly digested feed leads to reduced performance, an undesired effect. Adding carbohydrase enzymes to feed may make NPS more digestible without negatively impacting performance. 

The authors of this recent Journal of Animal Science article evaluated the carbohydrase xylanase and how it affected digestibility and gut fermentability of growing pigs. They hypothesized that adding xylanase to feed would benefit all of these areas. 

Growing gilts were fed a high insoluble fiber diet supplemented either with xylanase or no xylanase for 36 days. A low fiber control diet and a high fiber control diet were also included in the study. Pigs on the high fiber control diet had reduced apparent ileal, cecal and colonic digestibility (AID, ACOD and ACED), and apparent total tract digestibility (ATTD) of dry matter (DM), crude protein (CP), gross energy (GE), acid and neutral detergent fiber (ADF, NDF), and hemicellulose. Gilts on a high insoluble fiber diet supplemented with xylanase had some improvements in all of these areas, but benefit was not comparable to digestibility for the pigs on the low fiber control diet. 

Overall, the results of this study suggest that the addition of xylanase to the diets of pigs fed high insoluble diets does increase feed digestibility, but improvements are not comparable to digestibility in pigs fed a low fiber diet. It is possible that a combination of carbohydrases may be needed to improve digestibility to the desired level. More studies looking into the impacts of carbohydrases on feed digestibility in swine is justified. 

The original article, The influence of xylanase on the fermentability, digestibility, and physiochemical properties of insoluble corn-based fiber along the gastrointestinal tract of growing pigs, is now viewable in the Journal of Animal Science.