Effects of Momordica charantia polysaccharide on in vitro ruminal fermentation and cellulolytic bacteria

Four levels of Momordica charantia polysaccharide (MCP) supplements (0, 0.1, 0.3, 0.6 mg/ml) were designed to investigate the effects of MCP on ruminal fermentation and cellulolytic bacteria in vitro. The pH, ammonia-N (NH3-N) and volatile fatty acids (VFA) were measured at 6, 24, 48 h, whilst the cellulolytic bacteria population was determined at 6 and 24 h. The 0.6 mg/ml MCP inclusion decreased the theoretical maximum of gas production and the half-life. The NH3-N concentration was decreased by MCP at all doses at 24 h. The MCP inclusion increased the concentration of total VFA at 24 and 48 h and the acetate to propionate ratio, the molar proportion of isovalerate at 6 h, while decreased that of isobutyrate at 24 h and that of isovalerate, valerate at 24 and 48 h, respectively. The relative abundances of Ruminococcus albus and Ruminococcus flavefaciens were decreased at 6 h, while that of Butyrivibrio fibrisolvens was increased at all times of incubation and that of Fibrobacter succinogenes reached the greatest value at 0.6 mg/ml MCP supplementation at 24 h. This study demonstrated that the MCP had the ability to enhance the total VFA production, modulate the rumen fermentation pathway and influence the number of cellulolytic bacteria population.