Variability in the in vitro degradation of non-starch polysaccharides from wheat by feed enzymes

Wheat is one of the major feed ingredients in poultry diets. Non-starch polysaccharides (NSP) from wheat can have a negative impact on animal performance and therefore NSP-degrading feed enzymes are commonly added to wheat-based diets. Variation exists in the amount of NSP present in wheat as well as in the composition of the NSP-fraction. This interferes with designing optimal enzyme applications. The objective of this study was to examine the effects of a single xylanase preparation on the degradation of water-extractable (WE) and water-unextractable (WU) NSP-fractions of wheat samples with variable NSP-characteristics. Treatment of nine wheat samples with the same xylanase resulted in varying degrees of hydrolysis (DH). Degradation was between 2.6% and 40.3% for the WE-NSP fraction and between 12.8% and 25.5% for the WU-NSP fraction. Correlations were found between the DH of WE-arabinoxylan and the arabinose to xylose (A/X) ratio of this fraction (P<0.001, r = −0.82) and between the DH of WE-NSP and the A/X-ratio (P<0.001, r = −0.60). It is concluded that in vitro the response of wheat to xylanase varies for different batches of the cereal and that the A/X-ratio can be used as a predictor for the degradation of the WE-NSP fraction by the xylanase used in this study.