中文摘要：

【目的】研究利用茶皂素和丝兰皂苷混合物对瘤胃发酵和瘤胃内纤维降解菌变化的影响。【方法】采用2×4因子体外培养试验设计,因子一为对照组（不添加皂苷）和添加皂苷组（添加0.3%茶皂素和0.03%丝兰皂苷的混合物）,因子二为不同精粗比水平（20﹕80、40﹕60、50﹕50及60﹕40）,研究不同精粗比以及皂苷条件下对瘤胃发酵和瘤胃微生物的影响。【结果】茶皂素和丝兰皂苷的混合物能降低瘤胃pH,且精粗比为20﹕80时差异极显著（P〈0.01）;能够增加乙酸、丙酸、丁酸以及TVFA的浓度,但从各成分所占比例来看,茶皂素和丝兰皂苷混合物的添加降低了乙酸和丁酸的摩尔百分比例,增加了丙酸的摩尔百分比例,因此降低了乙酸/丙酸;能够降低原虫真蛋白产量而细菌真蛋白产量提高,细菌与原虫的比值提高且差异极显著（P〈0.01）。同一精粗比条件下,添加皂苷组产琥珀酸拟杆菌的相对数量均比非添加组高,除精粗比为20﹕80时差异不显著外（P〉0.05）,其它精粗比状态下差异极显著（P〈0.01）;除精粗比为40﹕60时外,其它精粗比状态下添加皂苷组白色瘤胃球菌和黄化瘤胃球菌的相对数量均比非添加组高。【结论】添加皂苷有降低瘤胃液中原虫总数和pH的趋势,并能够降低原虫真蛋白产量而提高细菌真蛋白产量。茶皂素和丝兰皂苷混合物对瘤胃发酵模式和瘤胃内纤维降解菌变化有一定影响,其作用效果受培养底物精粗比的显著影响。

英文摘要：

【Objective】An experiment was designed to explore the effect of Yucca schidigera saponin and tea saponin mixture and different concentrate/forage ratios In vitro on rumen fermentation and rumen fiberolytic bacterial activity.【Method】A 2×4 two factorial design of experiment was adopted： one factor was adding or without saponins（0.3% tea saponin and 0.03% Yucca schidigera extract）,the other was four different concentrate/forage ratios（20：80,40：60,50：50,and 60：40）.【Result】The results showed that the mixed saponins reduced pH and the group whose concentrate/forage ratio was 20：80 had significant effect（P0.05）.Concentrations of acetate,propionate,butyrate and total VFAs were increased by addition of the mixed saponins,however,from the molar ratio of VFAs it was found that the proportion of propionate and butyrate were decreased while the proportion of propionate was increased,so the acetate/propionate ratio descended.The mixed saponins increased ruminal bacterial protein yield whereas the yield of ruminal protozoal protein was decreased,and the ratio of bacterial protein/ protozoal protein was significantly increased（P0.05） compared with the control group.The relative amount of Fibrobacter succinogenes was extremely higher by addition of the mixed saponins whose concentrate/forage ratio was not 20：80.And the mixed saponins increased the relative amount of Ruminococcus flavefaciens and Ruminococcus albus except that the concentrate/forage ratio was 40：60.【Conclusion】Results indicate that this mixed saponins have effects on microbial fermentation and fibroliytic bacteria activities,and that the effects depend on the ratio of concentrate to rughage in the substrate.