Influence of exogenous fibrolytic enzymes and fumarate on methane production, microbial growth and fermentation in Rusitec fermenters.

Two incubation runs were conducted with Rusitec fermenters to investigate the effects of three additive treatments (mixed fibrolytic enzymes from Trichoderma longibrachiatum (FE), disodium fumarate (FUM) and both additives (MIX)) on rumen microbial growth and fermentation of a grass hay:concentrate (600 : 400 g/kg DM) substrate. Each fermenter received daily 20 g substrate DM. Application rate (per g substrate DM) was 34.3 endoglucanase, 0.57 exoglucanase, 24.7 xylanase and 5.51 amylase units for FE and 30 mg fumarate for FUM. MIX fermenters received both additives. Both FE and MIX increased (P 0.05). Supplementing with FUM increased (P 0.05) any other variable, thus suggesting that observed effects were due to fermentation of FUM itself. The lack of effects of FUM and the absence of differences between FE and MIX on most of the measured variables would indicate that beneficial effects found in MIX fermenters were mainly due to the action of FE. Combining FE and FUM as feed additives under the conditions of the present experiment did not further improve rumen fermentation, compared to FE alone.