In vitro Effects of Exogenous Fibrolytic Enzymes on Rumen Fermentation of Wild Guinea Grass (Panicum maximum)

This study aimed to evaluate the potential of commercial enzymes cellulase (CE), xylanase (XY) and the combination of CE + XY to improve rumen fermentation of Guinea grass ecotype 'A' (Panicum maximum). The experiment was carried out in a randomized complete block design. In vitro incubations were performed with four doses of individual enzymes and their combinations (1:1 from each enzyme) as 50, 100, 150 and 200 mu L enzymes with 500 mg substrate. In vitro gas production (IVGP) was measured at 4 h intervals. At the end of 24 h incubation in vitro rumen dry matter disappearance (IVRDMD), ammonia nitrogen (NH3- N), protozoa population and volatile fatty acid (VFA) were estimated. Supplementation with CE, XY and CE + XY significantly enhanced IVGP (control: 38.54 mL; CET1: 50.06 mL; XYT1: 54.27 mL and CET1 + XYT1: 52.77 mL) and IVRDMD (control: 46.78%; CET1: 51.21%; XYT1: 51.53% and CE1 + XY1: 52.64%). The rumen NH3-N production was significantly increased (P<0.05) with XY and CE + XY (control:100%; XYT1:108.88%; and CET1 + XYT1: 111.6%). Though the total VFA did not exhibit any significant change, acetate production was significantly reduced by CE + XY while the same treatment enhanced the butyrate production. The alterations of acetate and propionate profiles led to the significantly decreased acetate:propionate with CE and CE + XY. Insignificant deduction of rumen protozoa population was observed with all enzyme treatments. In conclusion, the supplementation of exogenous fibrolytic enzyme could improve the rumen fermentation of Guinea grass ecotype 'A'.