Department of Animal Nutrition, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Belgachia, Kolkata 700037, India.
Phytochemistry. 2010 Aug;71(11-12):1198-222. doi: 10.1016/j.phytochem.2010.05.010.
Recently, greenhouse gas emissions have been of great concern globally. Ruminant livestock due to production of methane during normal fermentation in the rumen contributes substantially to the greenhouse effects. During the recent decade, a paradigm shift has been initiated whether plant secondary metabolites (PSM) could be exploited as natural safe feed additives alternative to chemical additives to inhibit enteric methanogenesis. More than 200,000 defined structures of PSM have been known. Some plants or their extracts with high concentrations of bioactive PSM such as saponins, tannins, essential oils, organosulphur compounds, flavonoids and many other metabolites appear to have potential to inhibit methane production in the rumen. The possible mechanisms and effects of many PSM on rumen methanogenesis are not clearly understood. Saponins may decrease methanogenesis through the inhibition of rumen protozoa and in turn may suppress the numbers and activity of methanogens. Although the direct effect of saponins on methanogens has not been demonstrated, saponins might inhibit methanogens at high doses. Tannins may inhibit the methanogenesis directly and also via inhibition of protozoal growth. Essential oils, organosulphur compounds and flavonoids appear to have direct effects against methanogens, and a reduction of protozoa associated methanogenesis probably plays a minor role for these metabolites. The chemical structure and molecular weight of the PSM and chemical composition of diets dependent upon the different feeding regimes may influence the effects of PSM on methane production. Although PSM may negatively affect nutrient utilization, there is evidence that methanogenesis could be suppressed without adversely affecting rumen fermentation, which could be exploited to mitigate methane emission in ruminants.
最近，温室气体排放受到了全球的高度关注。反刍动物由于瘤胃正常发酵过程中产生甲烷，对温室效应有很大的贡献。在最近的十年中，人们已经开始转变观念，即是否可以利用植物次生代谢物（PSM）作为天然安全的饲料添加剂来替代化学添加剂，以抑制肠道甲烷生成。目前已经知道超过 20 万种 PSM 的明确结构。一些植物或其提取物含有高浓度的生物活性 PSM，如皂苷、单宁、精油、有机硫化合物、类黄酮和许多其他代谢物，似乎具有抑制瘤胃甲烷生成的潜力。许多 PSM 对瘤胃甲烷生成的可能机制和影响尚不清楚。皂苷可能通过抑制瘤胃原虫来减少甲烷生成，进而可能抑制甲烷菌的数量和活性。虽然尚未证明皂苷对甲烷菌有直接作用，但皂苷可能在高剂量下抑制甲烷菌。单宁可能直接抑制甲烷生成，也可能通过抑制原虫生长来抑制甲烷生成。精油、有机硫化合物和类黄酮似乎对甲烷菌有直接作用，而与原生动物相关的甲烷生成减少可能在这些代谢物中发挥次要作用。PSM 的化学结构和分子量以及日粮的化学成分取决于不同的饲养制度，可能会影响 PSM 对甲烷生成的影响。尽管 PSM 可能会对养分利用产生负面影响，但有证据表明，甲烷生成可以被抑制而不会对瘤胃发酵产生不利影响，这可以被利用来减轻反刍动物的甲烷排放。
