摘要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)orβ-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-man-nanase or XG alone provided comparable growth performance benefits and positively affected the gut environment,however,their combination further enhanced energy utilization and butyric acid pro-duction,and the latter may have implications in broiler's gut health and immune response.