Effects of an exogenous fibrolytic enzyme preparation on in vitro ruminal fermentation of three forages and their isolated cell walls

This study was completed to investigate whether a fibrolytic enzyme preparation with xylanase and cellulase activities (Fibrozyme™, Alltech Inc., Nicholasville, KY, USA), could stimulate in vitro rumen fermentation of alfalfa hay, grass hay and barley straw, and their isolated cell walls as neutral detergent fibre (NDF). Samples (500 mg) of each substrate were incubated in 120 ml bottles with 50 ml of buffered rumen fluid from sheep at 39 °C. The enzyme preparation was added directly to the bottles at the beginning of the incubation at levels of: 0 (control; CON), 50 mg/g substrate DM (LOWFIB) and 100 mg/g substrate DM (HIGHFIB). Effects on volatile fatty acid (VFA) production depended on substrate and incubation time. After incubation for 5 h, enzyme addition increased (P