Department of Animal Sciences, The Ohio State University, Columbus, OH 43210, USA.
J Appl Microbiol. 2012 Dec;113(6):1329-40. doi: 10.1111/j.1365-2672.2012.05440.x. Epub 2012 Sep 13.
The objective of this study was to comprehensively evaluate quillaja (QSP) and yucca saponin (YSP) products with respect to their effects on diversity of rumen bacteria and archaea, abundance of selected microbes, and feed degradability and fermentation.
Both QSP and YSP at doses 0-0.6 g l(-1) tended to increase degradability of feed substrate in in vitro rumen cultures, but to different extents. Neither one of the saponins affected the concentrations of ammonia, total volatile fatty acids, or molar proportion of acetate. However, QSP increased molar proportion of propionate and decreased that of butyrate, whereas YSP tended to decrease that of butyrate. As determined by qPCR, QSP and YSP did not affect the abundance of total bacteria or Ruminococcus albus. The QSP did not affect the abundances of Fibrobacter succinogenes or genus Prevotella, but tended to decrease that of Ruminococcus flavefaciens, whereas YSP significantly increased the abundance of R. flavefaciens and Prevotella, and numerically increased that of F. succinogenes. Both saponins increased archaeal abundance, although to small magnitudes (0.3-0.4 log). The protozoal populations were decreased significantly by QSP, but not by YSP. Based on DGGE and T-RFLP analysis, both saponins altered the bacterial community and species organization, but less so the archaeal community.
This study demonstrated that saponins, although not effective in mitigating methane emission, may improve feed utilization at low doses, and modulate ruminal microbial communities in a dose-dependent manner.
The results of this study suggest that saponins at low doses may directly stimulate the growth of some rumen bacteria including cellulolytic bacteria, thus improving digestibility of feeds, independent of their defaunation activity. In contrast, saponins at high doses modulate rumen fermentation characteristically similar to defaunation.
本研究旨在全面评估提取自帚状商陆（QSP）和丝兰的皂苷（YSP）产品对瘤胃细菌和古菌多样性、选定微生物丰度以及饲料降解率和发酵的影响。
QSP 和 YSP 在 0-0.6 g l(-1)剂量下均倾向于增加体外瘤胃培养物中饲料底物的降解率，但程度不同。两种皂苷均未影响氨、总挥发性脂肪酸或乙酸摩尔比例的浓度。然而，QSP 增加了丙酸的摩尔比例，降低了丁酸的摩尔比例，而 YSP 则倾向于降低丁酸的摩尔比例。通过 qPCR 确定，QSP 和 YSP 均不影响总细菌或 Ruminococcus albus 的丰度。QSP 不影响 Fibrobacter succinogenes 或属 Prevotella 的丰度，但倾向于降低 Ruminococcus flavefaciens 的丰度，而 YSP 显著增加了 R. flavefaciens 和 Prevotella 的丰度，并使 F. succinogenes 的丰度略有增加。两种皂苷均增加了古菌的丰度，尽管幅度较小（0.3-0.4 log）。QSP 显著降低了原生动物种群，但 YSP 则没有。基于 DGGE 和 T-RFLP 分析，两种皂苷均改变了细菌群落和物种组织，但对古菌群落的影响较小。
本研究表明，皂苷虽然不能有效减少甲烷排放，但在低剂量下可能会提高饲料利用率，并以剂量依赖的方式调节瘤胃微生物群落。
本研究结果表明，低剂量的皂苷可能直接刺激一些瘤胃细菌（包括纤维素分解菌）的生长，从而提高饲料的消化率，而不依赖于其去纤作用。相比之下，高剂量的皂苷会以类似于去纤作用的方式调节瘤胃发酵特性。
