Influence of cellulase or xylanase on the in vitro rumen gas production and fermentation of corn stover

In vitro gas production (GP) technique was used to investigate effect of exogenous enzymes cellulase (CEL) or xylanase (XYL) at different doses on in vitro fermentation characteristics of corn stover. Enzymes were supplemented at 0 (control), 10, 20, 40 and 80 μg/g DM. Gas production was determined at 2, 4, 6, 8, 10, 12, 24, 36, 48 and 72 h of incubation. After 72 h, the incubation was stopped and supernatant pH was determined, and filtered to determine dry matter (DMD), neutral detergent fiber (NDFD) and acid detergent fiber (ADFD) degradabilities. Interaction effects occurred for enzyme type and dose for all measured gas parameters with exception of the lag time, DMD, organic matter degradability (OMD), NDFD, metabolizable energy (ME), short chain fatty acids (SCFA) and microbial crude protein (MCP) production. Cellulase and XYL increased GP (P<0.05) at different incubation hours with better results at the dose of 40 μg/g DM. The dose 80 μg XYL/g DM had the lowest GP compared to other doses. In addition, CEL and XYL decreased pH with increasing OMD, ME, SCFA and MCP production at 40 μg/g DM of corn stover. The present results suggested that the level of CEL and XYL at 40 μg/g DM have higher GP than other levels of enzymes, imply this level can be more effectively to improve rumen fermentation; however, the difference of XYL between treatments and control was less than that of CEL.