Patra Amlan K, Yu Zhongtang
Department of Animal Sciences, The Ohio State UniversityColumbus, OH, USA; Department of Animal Nutrition, West Bengal University of Animal and Fishery SciencesKolkata, India.
Department of Animal Sciences, The Ohio State University Columbus, OH, USA.
Front Microbiol. 2015 Dec 22;6:1434. doi: 10.3389/fmicb.2015.01434. eCollection 2015.
This study investigated the effects of garlic oil (0.25 g/L), nitrate (5 mM), and quillaja saponin (0.6 g/L), alone and in binary or ternary combinations, on methanogenesis, rumen fermentation, and abundances of select microbial populations using in vitro rumen cultures. Potential adaptation to these compounds was also examined by repeated transfers of the cultures on alternate days until day 18. All treatments except saponin alone significantly decreased methanogenesis. Ternary combinations of garlic oil, nitrate, and saponin additively/synergistically suppressed methane production by 65% at day 2 and by 40% at day 18. Feed digestion was not adversely affected by any of the treatments at day 2, but was decreased by the combinations (binary and ternary) of garlic oil with the other inhibitors at days 10 and 18. Saponin, alone or in combinations, and garlic oil alone lowered ammonia concentration at day 2, while nitrate increased ammonia concentration at days 10 and 18. Total volatile fatty acid concentration was decreased by garlic oil alone or garlic oil-saponin combination. Molar proportions of acetate and propionate were affected to different extents by the different treatments. The abundances of methanogens were similar among treatments at day 2; however, garlic oil and its combination with saponin and/or nitrate at day 10 and all treatments except saponin at day 18 significantly decreased the abundances of methanogens. All the inhibitors, either alone or in combinations, did not adversely affect the abundances of total bacteria or Ruminococcus flavefaciens. However, at day 18 the abundances of Fibrobacter succinogenes and Ruminococcus albus were lowered in the presence of garlic oil and saponin, respectively. The results suggest that garlic oil-nitrate-saponin combination (at the doses used in this study) can effectively decreases methanogenesis in the rumen, but its efficacy may decrease while inhibition to feed digestion can increase over time.
本研究利用体外瘤胃培养物，研究了大蒜油（0.25 g/L）、硝酸盐（5 mM）和皂树皂苷（0.6 g/L）单独使用以及二元或三元组合对甲烷生成、瘤胃发酵和特定微生物种群丰度的影响。还通过每隔一天重复转移培养物直至第18天，来检测对这些化合物的潜在适应性。除单独使用皂树皂苷外，所有处理均显著降低了甲烷生成。大蒜油、硝酸盐和皂树皂苷的三元组合在第2天可累加/协同抑制65%的甲烷生成，在第18天可抑制40%。在第2天，任何处理均未对饲料消化产生不利影响，但在第10天和第18天，大蒜油与其他抑制剂的组合（二元和三元）降低了饲料消化率。单独使用皂树皂苷或其组合以及单独使用大蒜油在第2天降低了氨浓度，而硝酸盐在第10天和第18天增加了氨浓度。单独使用大蒜油或大蒜油-皂树皂苷组合降低了总挥发性脂肪酸浓度。不同处理对乙酸和丙酸的摩尔比例有不同程度的影响。在第2天，各处理间产甲烷菌的丰度相似；然而，在第10天，大蒜油及其与皂树皂苷和/或硝酸盐的组合，以及在第18天除皂树皂苷外的所有处理均显著降低了产甲烷菌的丰度。所有抑制剂单独或组合使用均未对总细菌或黄化瘤胃球菌的丰度产生不利影响。然而，在第18天，在大蒜油和皂树皂苷存在的情况下，琥珀酸丝状杆菌和白色瘤胃球菌的丰度分别降低。结果表明，大蒜油-硝酸盐-皂树皂苷组合（在本研究使用的剂量下）可有效降低瘤胃中的甲烷生成，但随着时间推移其功效可能会降低，而对饲料消化的抑制作用可能会增加。
