In vitro enzymatic hydrolysis for xylo-oligosaccharide release from wheat-, maize-, maize and wheat distillers dried grains with solubles- and sorghum-based broiler diets

The prebiotic effects of xylo-oligosaccharides (XOS) in poultry are well documented, but their detailed formation during xylan hydrolysis in the gastrointestinal tract remains unclear. This is due mainly to complex interactions among exogenous enzymes used, gut microbiota and the structures of in-feed xylans (including arabinoxylans). This study employed a two-step in vitro digestion model simulating the chicken gastrointestinal environment to evaluate XOS production via enzymatic hydrolysis using a xylanase and β-glucanase (XG) preparation across four broiler diets based on wheat, maize, sorghum or maize-wheat distiller's dried grain with solubles (DDGS). To gain insight into the structural accessibility of xylan-based polysaccharides in diets, xylan profiling was conducted. Xylan profiling showed that the total xylan content was highest in the maize-wheat DDGS-based diet, and lowest in the sorghum-based diet. The wheat-based diet was intermediate, with higher levels than maize, but lower than the maize-wheat DDGS-based diet. In the wheat-based diet, XG increased (P < 0.05) xylobiose (XOS2: 8.3 to 13.7 mg/kg), xylotriose (XOS3: 2.0 to 5.2 mg/kg), xylotetraose (XOS4: 1.2 to 2.6 mg/kg), and xylopentaose (XOS5: 0.7 to 1.6 mg/kg). In the maize-based diet, XG increased (P = 0.006) XOS2 (3.1 to 3.9 mg/kg), while XOS3 (0.7 mg/kg) remained unchanged; XOS4 and XOS5 were undetected. In the maize-wheat DDGS-based diet, XG markedly increased (P < 0.001) XOS2 (21.4 to 283.9 mg/kg), XOS3 (26.4 to 227.9 mg/kg), and XOS4 (8.6 to 22.8 mg/kg), while XOS5 (2.9 mg/kg) was unaffected. In the sorghum-based diet, XG increased (P < 0.001) XOS2 (7 to 10.6 mg/kg), while XOS3 (0.9 mg/kg) remained unchanged; XOS4 and XOS5 were undetected. These findings provide in vitro evidence that XG can release mid-length XOS from wheat- and maize-wheat DDGS-based diets, supporting their potential to enhance gut health in broilers.