Temperature Resistance of Xylanase Inhibitors and the Presence of Grain‐Associated Xylanases Affect the Activity of Exogenous Xylanases Added to Pelleted Wheat‐Based Feeds

Abstract

ABSTRACTThe addition of exogenous xylanases (EX‐XYL) to wheat‐based poultry feeds is a common practice today. Wheat contains xylanase inhibitors (XI) and grain‐associated xylanases (GA‐XYL), which could affect the action of the EX‐XYL. In this study, both GA‐XYL and XI activity in feeding‐quality wheat were assessed. In addition, the effect of the conditions during digestion in monogastrics and the effects of pelleting at different conditioning temperatures on GA‐XYL and XI were investigated. The GA‐XYL activity varied between no activity and 0.821 XU/g. In contrast, the XI activity was consistently high in all wheat samples and ranged between 259 and 331 IU/g. Simulating the digestive process did not affect the activities of GA‐XYL or XI. Pelleting at 85°C or higher reduced the XI activity up to 46%. GA‐XYL, however, were more heat‐sensitive, and their activity was reduced to 67% at 60°C. The extract viscosity increased and the release of reducing sugars decreased at higher conditioning temperatures. In addition, the net effect of EX‐XYL on extract viscosity increased at higher temperatures, whereas the release of reducing sugars was not affected. In conclusion, XI affected the action of EX‐XYL during the digestive process, and pelleting did not eliminate their negative effects.