Abstract
The effects of wilting and added enzymes on fermentation and in vitro digestion of rhodesgrass and guineagrass silages were examined. First cuts of the two forages were ensiled in laboratory silos directly or after being wilted for 4 h with or without cell wall degrading enzymes (0.2 g kg^<-1>). Silos were opened after 45 d and the chemical composition and the fermentation quality were determined. The silages were subjected to in vitro rumen incubation and the degradation of NDF was determined. Without enzymes rhodesgrass silage failed to achieve lactate type fermentation, while guineagrass silage had high proportion of lactate even without any of the treatments. Wilting inhibited the organic acid production but decreased the proportion of lactate in rhodesgrass silage. Use of enzymes improved the preservation of both the silages, as evidenced by the increase of lactate and the decrease of pH value and NH3-N. The contents of NDF and ADF were reduced by enzyme treatment, but the reduction was considerably suppressed when forages were wilted before ensiling. In vitro degradation of NDF was low in direct-cut rather than wilted silage. Addition of enzymes also lowered the degradation, but this effect was restrictedly found in guineagrass silage incubated for 72h. These results indicate that although added cell wall degrading enzymes can promise an improved fermentation of tropical grass silage, the benefit would be less pronounced when treated with low moisture material.
