Ruminants inhabit the consortia of gut microbes that play a critical functional role in their maintenance and nourishment by enabling them to use cellulosic and non-cellulosic feed material. These gut microbes perform major physiological activities, including digestion and metabolism of dietary components, to derive energy to meet major protein (65–85%) and energy (ca 80%) requirements of the host. Owing to their contribution to digestive physiology, rumen microbes are considered one of the crucial factors affecting feed conversion efficiency in ruminants. Any change in the rumen microbiome has an imperative effect on animal physiology. Ruminal microbes are fundamentally anaerobic and produce various compounds during rumen fermentation, which are directly used by the host or other microbes. Methane (CH₄) is produced by methanogens through utilizing metabolic hydrogen during rumen fermentation. Maximizing the flow of metabolic hydrogen in the rumen away from CH₄ and toward volatile fatty acids (VFA) would increase the efficiency of ruminant production and decrease its environmental impact. Understanding of microbial diversity and rumen dynamics is not only crucial for the optimization of host efficiency but also required to mediate emission of greenhouse gases (GHGs) from ruminants. There are various strategies to modulate the rumen microbiome, mainly including dietary interventions and the use of different feed additives. Phytogenic feed additives, mainly plant secondary compounds, have been shown to modulate rumen microflora and change rumen fermentation dynamics leading to enhanced animal performance. Many in vitro and in vivo studies aimed to evaluate the use of plant secondary metabolites in ruminants have been conducted using different plants or their extract or essential oils. This review specifically aims to provide insights into dietary interactions of rumen microbes and their subsequent consequences on rumen fermentation. Moreover, a comprehensive overview of the modulation of rumen microbiome by using phytogenic compounds (essential oils, saponins, and tannins) for manipulating rumen dynamics to mediate CH₄ emanation from livestock is presented. We have also discussed the pros and cons of each strategy along with future prospective of dietary modulation of rumen microbiome to improve the performance of ruminants while decreasing GHG emissions.

反刍动物栖息在肠道微生物群中，这些微生物通过使它们能够使用纤维素和非纤维素饲料，在维持和营养方面发挥着关键的功能作用。这些肠道微生物执行主要的生理活动，包括膳食成分的消化和代谢，以获得能量以满足宿主对主要蛋白质（65-85%）和能量（约 80%）的需求。由于其对消化生理学的贡献，瘤胃微生物被认为是影响反刍动物饲料转化效率的关键因素之一。瘤胃微生物群的任何变化都会对动物生理产生重要影响。瘤胃微生物本质上是厌氧的，在瘤胃发酵过程中产生各种化合物，直接被宿主或其他微生物利用。甲烷(CH ₄ )是由产甲烷菌在瘤胃发酵过程中利用代谢氢产生的。最大限度地提高瘤胃中代谢氢从 CH ₄流向挥发性脂肪酸 (VFA) 的流量，将提高反刍动物的生产效率并减少其对环境的影响。了解微生物多样性和瘤胃动态不仅对于优化宿主效率至关重要，而且对于调节反刍动物温室气体 (GHG) 的排放也至关重要。调节瘤胃微生物组的策略有多种，主要包括饮食干预和使用不同的饲料添加剂。植物源性饲料添加剂（主要是植物次生化合物）已被证明可以调节瘤胃微生物区系并改变瘤胃发酵动力学，从而提高动物生产性能。 许多旨在评估植物次生代谢物在反刍动物中的用途的体外和体内研究已使用不同的植物或其提取物或精油进行。本综述的具体目的是深入了解瘤胃微生物的饮食相互作用及其对瘤胃发酵的后续影响。此外，还全面概述了通过使用植物源化合物（精油、皂苷和单宁）来调节瘤胃微生物组，以操纵瘤胃动力学以介导牲畜的 CH ₄排放。我们还讨论了每种策略的优缺点以及瘤胃微生物组饮食调节的未来前景，以提高反刍动物的性能，同时减少温室气体排放。