毛茛科植物提取物添加量对瘤胃微生物体外动态发酵的影响

试验采用活体外产气量法研究毛茛科植物提取物不同添加水平对瘤胃微生物体外发酵的影响。试验采用单因子完全随机化试验设计,以小麦面粉为底物进行体外发酵。瘤胃液供体动物为3头装有永久性瘤胃瘘管的本地黄牛,日粮精料水平为30%(日饲喂2次)。植物提取物添加水平分别为0、100、200、300和400mg/L。结果表明:随着毛茛科植物提取物添加水平的提高,小麦面粉24h的DM消化率呈线性下降(P=0.0002),活体外产气速度呈二次曲线规律降低(P=0.0001),而产气延滞期线性增加(P=0.0001),理论最大产气量呈二次曲线规律增加(P=0.0001)。随着植物提取物添加水平的提高,发酵液pH值呈二次曲线增加(P<0.024)。各培养时间点乳酸含量均较低(P<1mmol/L),且各处理之间差异不显著(P>0.10)。提高植物提取物添加水平导致tVFA产量呈二次曲线趋势下降(P<0.01)。通过本试验可得出:毛茛科植物提取物可以通过降低瘤胃发酵的产气速度、提高发酵液pH值以及乙酸和丁酸摩尔比例来调控瘤胃微生物体外发酵,其中植物提取物的适宜添加水平为200～300mg/L。

Effect of Addition Levels of Ranunculaceous Plant Extract on Kinetics of Rumen Microbial Fermentation in vitro

An in vitro gas production experiment was conducted to evaluate the effect of various concentrations of Rannunculaceous plant extract on fermentation of wheat flour by mixed ruminal microorganisms. The syringe fermenters were inoculated with ruminal fluid obtained from three ruminally cannulated steers receiving diets with 30% concentrate level. Wheat flour(0.5 g DM in each syringe) was used as a sole fermentation substrate. Ranunculaceous plant extract was added to the incubation syringes(n = 9) to achieve final concentrations of 0, 100, 200, 300 and 400 mg/L. As the concentration of the plant extract increased, there was a linear decrease in digestibility of DM of wheat flour(P = 0.0002). Increasing concentration of the plant extract resulted in a linear increase in lag time of gas production(P = 0.0001), but in a quadratic decrease in gas production rate(P = 0.0001). At each incubation time point of 6 h, 12 h or 24 h, the concentrations of lactate was not influenced(P > 0.10) because the concentration was very low (less than 1 mmol/L). Plant extract quadratically decreased total VFA concentration(P < 0.01). In conclusion, the crude extract of the Ranunculaceous plant can be functioned as a potential manipulator for the ruminal fermentation by mixed microorganisms in vitro. The concentration of the extract between 200 mg/L and 300 mg/L would be appropriate for the practical use.