Carbohydrate Composition, in Vitro Digestion, and Effects of Xylanase and Phytase on Nutrient and Energy Digestibility by Pigs in Grains and Grain Coproducts By

Two experiments were conducted to determine the efficacy of xylanase and phytase supplementation to swine diets based on corn, soybean meal, distillers dried grains with solubles, and wheat bran. In Exp. 1, the apparent ileal digestibility (AID) and the apparent total tract digestibility (ATTD) of energy and nutrients were determined. Eight pigs (initial BW: 24.1 ± 1.9 kg) were surgically fitted with a T-cannula in the distal ileum and randomly allotted to an 8 × 8 Latin square design with 8 diets and 8 periods. Four diets were formulated to meet the pig’s AA requirements using a low amount of crystalline AA, whereas 3 additional diets were formulated to contain greater amounts of crystalline AA. The last diet was unrelated to this experiment. The 4 low-AA diets included the control diet that contained no phytase or xylanase, the phytase diet that contained 500 phytase units (FTU)/kg, and 2 diets that contained 500 FTU/kg of phytase and 2,000 or 4,000 xylanase units/kg. The 3 high-AA diets contained 500 FTU/kg of phytase and 2,000, 4,000, or 8,000 xylanase units/kg. Results indicated phytase improved (P < 0.05) the AID of CP, Ca, P, and most AA by 2.2, 13.9, 9.4, and approximately 2%, respectively, compared with the control diet. Phytase also improved (P < 0.05) the ATTD of Ca and P by 18.1 and 13.8%, respectively, compared with the control diet. Xylanase added to the low-AA diets improved (P < 0.05) the AID of DM, GE, and NDF by 2.3, 1.9, and 5.8%, respectively, compared with the