Xylanase increased the ileal digestibility of nonstarch polysaccharides and concentration of low molecular weight nondigestible carbohydrates in pigs fed high levels of wheat distillers dried grains with solubles1,2

The objective was to study the effect of a commercially available xylanase (CAX), an experimental xylanase (EX), and EX in combination with protease (EXP) on the degradation of nondigestible carbohydrates (NDC) and apparent ileal digestibility (AID) of nutrients in wheat distillers dried grains with solubles (wDDGS). The control and 3 enzyme diets contained 96% wDDGS supplemented with vitamins, minerals, l-lysine, and chromic oxide as a digestibility marker in addition to enzyme premix. Eight ileal cannulated pigs were fed 4 experimental diets containing 96% wDDGS—a control diet or 1 of 3 diets with CAX, EX, or EXP—in a double 4 × 4 Latin square design. The experimental period lasted 7 d; adaptation lasted 4 d, and the ileal digesta were collected for 8 h on d 5 and 7, when spot samples of feces were also collected. Digesta samples were analyzed for NDC, total and soluble nonstarch polysaccharides (NSP), low molecular weight (LMW) NDC, OM, CP, fat, starch, and marker. Compared with the control diet, addition of CAX, EX, and EXP increased the AID of arabinoxylan by 32 (P < 0.001), 28 (P = 0.001), and 24% (P = 0.004), respectively. In addition, EXP increased the AID of noncellulosic polysaccharide glucose by 21% compared with the control (P = 0.005). Compared with the control, addition of EX, EXP, and CAX decreased the concentration of soluble arabinoxylan in ileal digesta by 40 (P < 0.0001), 40 (P < 0.0001), and 21% (P = 0.022), respectively. Furthermore, addition of CAX, EXP, and EX increased the concentration of LMW arabinoxylan in ileal digesta by 40 (P = 0.0001), 36 (P = 0.0006), and 24% (P = 0.023), respectively, compared with the control. Addition of EX and EXP decreased the concentration of soluble NSP of ileal digesta by 25 (P = 0.001) and 26% (P < 0.001), respectively, compared with the control diet. Addition of CAX (P < 0.0001) and EXP (P = 0.013) increased the arabinose-to-xylose ratio in the insoluble arabinoxylan fraction in ileal digesta compared with the control diet, and CAX increased the uronic acid-to-xylose ratio of the ileal insoluble NSP fraction (P < 0.0001) compared with the control diet. Enzyme addition did not affect AID of OM, CP, starch, and fat (P > 0.3). In conclusion, addition of xylanases to wDDGS diets increased the ileal digestibility of NSP and generated LMW NDC components in the small intestine of pigs but did not affect ileal digestibility of nutrients in the current study.