Effect of Yeast Culture on Mixed Rumien Microorganism Fermentation In Vitro

The effect of yeast culture on rumen fermentation was investigated in vitro batch cultures of mixed rumen microorganism from goats.Substrate-clover plus concentrate(4:6)was fermented in the presence of yeast culture(0,0.75 g/L,1.50 g/L,2.25 g/L).The results showed that the pH of all treatments decreased significantly compared with the control(P0.05).At 24 h,36 h and 48h,compared with the control group,the NH3-N concentration of all treatments decreased significantly(P0.05),the TVFA concentration in 2.25 g/L yeast culture group increased significantly(P0.05).The acetate concentration was not affected by treatments,while the propionate concentrate of all treatments increased significantly compared with the control at 24 h and 48h(P0.05).The acetate to propionateratio in 1.50 g/L yeast culture groups was less than the control group at 24 h and 48 h(P0.05).The 48 h ac cumulative gas production in 1.50 g/L and 2.25 g/L yeast culture groups increased significantly compared with the control during the whole fermentation period,however,the degradation of dry matter was not affected by treatments.The results suggested that yeast culture could change the fermentation pattern with a significant increase of TVFA concentration and a significant decrease of acetate to propionate ratio.