83 The impact of xylanase on arabinoxylan hydrolysis when included in corn or wheat based diets fed to swine

摘要

Carbohydrases added to swine diets hydrolyze non-starch polysaccharides (NSP) to smaller oligosaccharides, decreasing their degree of polymerization (DP). Wheat contains more NSP in the form of arabinoxylans (AX), however corn AX have higher arabinose:xylose. This experiment determined the potential for a differential response to the carbohydrase, xylanase, when added to corn or wheat based diets for swine. Twelve ileal cannulated barrows (BW 37±2.1kg) were used in a modified crossover design with a 2x2 factorial arrangement of treatments in two periods (n = 6). Grain (81.5% corn or 90.5% wheat) and xylanase (±0.01%, 16,000 XU/kg feed) were main effects. The crossover occurred only between xylanase; pigs remained on the same grain throughout and pig was randomized within sequence. Isoenergetic/isonitrogenous (3,500 Kcal ME/kg, 0.87% SID Lys) diets were fed at 3x maintenance for 18d; fecal and digesta samples were collected on d15-16 and d17-18, respectively. Ileal energy digestibility tended to improve with xylanase (71.3–73.8%; P < 0.10). Fecal energy digestibility was improved by xylanase in wheat, but not corn, based diets (grain*xylanase, P < 0.05). Ileal butyric acid was highest when pigs received the wheat diet without xylanase (grain*xylanase, P < 0.05). Xylanase had no effect on fecal short chain fatty acids (P > 0.10). Pigs fed wheat diets had increased percent fecal propionic and lower butyric and valeric acid than those fed corn diets (P < 0.05). Ileal arabinose:xylose ratio was reduced with xylanase in corn, but not wheat diets, while the opposite was observed in fecal samples (grain*xylanase, P < 0.05). Ileal samples from pigs receiving corn without xylanase had the highest AX-DP (grain*xylanase, P < 0.05). Fecal AX-DP was reduced with xylanase inclusion (P < 0.05) and was lower in wheat, than corn based diets (P < 0.05). Xylanase decreased AX-DP throughout the gastrointestinal tract and tended to improved ileal energy digestibility in corn and wheat based diets.