Supplementation of β-mannanase alone or in combination with xylanase and β-glucanase enhanced growth performance, non-starch polysaccharide degradation, and gastrointestinal environment of broilers offered wheat-based diets.

Nutritional strategies to enhance the utilization of undigested dietary components for sustainability and better production efficiency are constantly being explored in poultry. This study aimed to investigate the effects of β-mannanase alone or in combination with a xylanase and β-glucanase preparation on growth performance, nutrient and energy utilization, and gastrointestinal environment of broilers offered wheat-based diets. At d 0 post-hatch, 384 mixed-sex Cobb 500 broilers were assigned to 4 treatments in a 2 × 2 factorial arrangement, with β-mannanase (with or without) and xylanase + β-glucanase (XG, with or without) as the 2 factors. Each treatment contained 8 replicates of 12 birds per pen and 96 birds per treatment. During d 0 to 10, birds offered diets supplemented with XG (P = 0.023) or β-mannanase (P = 0.010) had higher weight gain, and β-mannanase supplementation improved (P = 0.040) feed conversion ratio (FCR) compared to the unsupplemented control. During d 0 to 35, XG increased (P = 0.035) and β-mannanase tended (P = 0.096) to increase the weight gain of birds. The combination of β-mannanase and XG interacted (P = 0.016) for FCR where either XG or β-mannanase alone improved FCR compared to the unsupplemented control but there were no further improvements when they were added in tandem. At d 21, XG decreased (P < 0.001) ileal digesta viscosity, and XG (P < 0.001) or β-mannanase (P = 0.004) decreased ileal pH. β-Mannanase increased total tract retention of dry matter (DM, P = 0.001), nitrogen (N, P = 0.019), soluble non-starch polysaccharides (NSP, P = 0.020), insoluble NSP (P < 0.001), total NSP (P < 0.001), free oligosaccharides (P = 0.023), calcium (Ca, P < 0.001), and showed tendency (P = 0.098) to increase nitrogen-corrected apparent metabolizable energy (AMEn). Dietary XG increased apparent total tract retention of DM (P = 0.017), soluble NSP (P < 0.001), Ca (P = 0.005), apparent metabolizable energy (AME) (P = 0.024), and AMEn (P = 0.020). β-Mannanase and XG combination showed a tendency (P = 0.073) to interact for AME such that the highest AME was observed in this group. β-Mannanase and XG combination interacted (P = 0.034) for butyric acid concentration in the caecal contents where β-mannanase or XG alone increased the concentration of butyric acid compared to the unsupplemented control which was further enhanced when they were added in tandem. β-Mannanase (P = 0.049) or XG (P = 0.046) increased total short-chain fatty acid concentration in the caecal contents. These findings suggest that dietary supplementation of β-mannanase or XG alone provided comparable growth performance benefits and positively affected the gut environment, however, their combination further enhanced energy utilization and butyric acid production, and the latter may have implications in broiler's gut health and immune response.