高精料条件下酵母培养物对混合瘤胃微生物体外发酵的影响

采用山羊瘤胃液的体外批次培养研究了酵母培养物对混合瘤胃微生物体外发酵的影响。发酵底物精粗比为7:3,酵母培养物添加量为0、0.75 g/L1、.5 g/L2、.25 g/L。结果表明,发酵各时间点,各处理组的pH值较对照组均显著降低(P<0.05)。与对照组相比,发酵24 h、36 h4、8 h时,各处理组氨氮浓度显著降低(P<0.05),2.25 g/L处理组的TVFA浓度显著升高(P<0.05)。各时间点,三个处理组的乙酸浓度与对照组相比差异均不显著,而发酵24 h4、8 h时,三个处理组的丙酸浓度均高于对照组(P<0.05)。发酵24 h、48 h时,1.50 g/L处理组的乙丙比较对照组显著降低(P<0.05)。在整个发酵期内,1.50 g/L、2.25 g/L处理组的累积产气量均显著高于对照组(P<0.05),各组干物质消失率无显著差异(P>0.05)。结果显示,酵母培养物能够显著提高瘤胃VFA浓度,降低乙酸/丙酸比例,改变瘤胃发酵类型。

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(P<0.05).At 24 h,36 h and 48h,compared with the control group,the NH3-N concentration of all treatments decreased significantly(P<0.05),the TVFA concentration in 2.25 g/L yeast culture group increased significantly(P<0.05).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(P<0.05).The acetate to propionateratio in 1.50 g/L yeast culture groups was less than the control group at 24 h and 48 h(P<0.05).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.