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

Abstract

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' (<em>Panicum maximum</em>). The experiment was carried out in a randomized complete block design. <em>In vitro</em> incubations were performed with four doses of individual enzymes and their combinations (1:1 from each enzyme) as 50, 100, 150 and 200 µL enzymes with 500 mg substrate. <em>In vitro </em>gas production (IVGP) was measured at 4 h intervals. At the end of 24 h incubation <em>in vitro</em> 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'.