Effect of exogenous xylanase on rumen in vitro gas production and degradability of wheat straw

The objective of this study was to determine effects of xylanase on in vitro gas production (GP) and in sacco degradability of wheat straw. Rumen fluid was obtained from three Mongolian native goats fitted with permanent rumen cannulas. The trial consisted of five doses (0, 0.5, 1.0, 1.5, 2.0μL/g of substrate) of a commercial xylanase (Dyadic®xylanase PLUS, Dyadic International, Inc., Jupiter, FL, USA). For the in sacco degradability, different levels of xylanase enzyme were added directly onto 2g of wheat straw in nylon bags and incubated in the rumen for 3, 6, 12, 24 and 48h to estimate degradability of wheat straw. Total GP increased (P<0.001) at all times of incubation at intermediate levels of xylanase. Methane production had a similar pattern at 3 and 12h of incubation; increased linearly at 24h of incubation, and was unaffected at 6 and 48h of incubation. Rumen NH3-N concentration increased linearly at 3h and the highest values were observed with intermediate enzyme levels. All ruminal volatile fatty acids increased linearly with intermediate levels of the fibrolytic enzyme. The in sacco rate of dry matter degradation decreased linearly (P=0.020) with increasing enzymes. Intermediate levels of xylanase improved rumen kinetic fermentation and degradability. The outcome of this research indicated that the application of xylanase enzyme could improve in vitroGP fermentation of wheat straw.