The response of broilers to xylanase and β-glucanase combination in maize-based diets containing wheat distillers'...

Broiler diets containing wheat distillers' dried grain with solubles (wDDGS) have higher levels of non-starch polysaccharides (NSP) compared to conventional maize-soybean meal-based diets, which can increase intestinal viscosity and impair nutrient utilisation. This study investigated the effects of supplemental xylanase and β-glucanase (XG) preparation on growth performance, ileal flow of soluble NSP constituent sugars, and the gastrointestinal environment in broilers fed maize-based diets with varying wDDGS levels. A total of 768 mixed-sex Cobb 500 broilers (on hatch day and 40 ± 1 g) were assigned to 6 treatments in a 3 × 2 factorial arrangement, with wDDGS levels (none), 6%-12% (medium), 12%-20% (high) with or without XG supplementation across eight replicate pens of 16 birds each, totaling 128 birds per treatment. From d 0 to 10, XG and wDDGS interacted for weight gain (WG; P = 0.019), with XG improving WG only in broilers fed high wDDGS diets but not in others. High wDDGS worsened feed conversion ratio (FCR; P = 0.014), while XG tended to improve it (P = 0.079). From d 21 to 35, XG increased WG (P = 0.001) and improved FCR (P = 0.006) regardless of wDDGS level. From d 0 to 35, XG increased WG (P < 0.001) and tended to improve FCR regardless of wDDGS level (P = 0.097). Medium and high wDDGS diets raised ileal viscosity at d 21 (P = 0.020) and high wDDGS at d 35 (P = 0.002). XG lowered ileal viscosity at d 21 (P = 0.006) and d 35 (P = 0.001). Medium and high wDDGS diets resulted in higher ileal flow of soluble NSP constituent sugars, including soluble arabinose, mannose, and glucose compared with the control (P < 0.001). XG reduced soluble arabinose (P = 0.012) and total soluble NSP constituent sugars (P = 0.007). Dietary XG and wDDGS interacted for ileal soluble xylose concentration within the NSP fraction (P = 0.018), where XG reduced soluble xylose in broilers fed medium and high wDDGS diets but not the control (no wDDGS). High wDDGS diets increased the ileal flow of insoluble NSP constituent sugars vs. the control diet with no wDDGS (P < 0.001). XG supplementation did not affect ileal insoluble NSP constituent sugars (P > 0.05), but tended to elevate xylose in the free oligosaccharide fraction in the ileum (P = 0.053). XG increased caecal propionic acid (P = 0.004) and tended to increase caecal short-chain fatty acids (P = 0.060). In conclusion, XG supplementation enhanced broiler performance in maize-based diets with wDDGS by reducing soluble NSP and small intestinal viscosity while promoting hindgut fermentation, though optimised dosing is needed for high wDDGS diets to support sustainable broiler nutrition.