Abstract: Methane （CH₄） is recognized as the second-largest contributor to greenhouse gas emissions. The enteric fermentation from ruminant livestock accounts for approximately 40% of the total anthropogenic CH₄ emissions. This poses a major obstacle to national efforts in combating global warming and achieving the “dual carbon goals”. In this study， we systematically synthesized the existing knowledge on enteric methane emissions from ruminant livestock and their measurement methods. The results indicated that there were significant variations in CH₄ emission factors across regions， livestock species and feeding stages. There was a larger span of emissions in warmer and humid regions than in colder and drier regions. Larger-bodied animals generally produced higher emissions. For example， female breeding buffaloes emited up to 110.6 kg·head^-1·a^-1， whereas emissions from sheep and goats were considerably lower （approximately 12~13 kg·head^-1·a^-1）. Overall， the emission factors ranged widely from 6.5 to 110.6 kg·head^-1·a^-1 depending on production stages and feeding systems. Key measurement techniques for enteric methane included the sulfur hexafluoride （SF₆） tracer technique， respiration chamber/headbox systems， the GreenFeed system， in vitro fermentation， laser-based methods， and predictive modeling. Promising mitigation strategies encompassed dietary composition adjustments， feed additives， rumen microbiota manipulation， vaccine-based methods， genetic improvement， and optimized management practices， as well as emerging approaches such as targeted inhibition of key methanogenic enzymes， modulation of hydrogen metabolic shunting， and remodeling the rumen microbiome through gene editing. Future studies should prioritize establishing accurate methodologies for accounting enteric CH₄ emissions throughout the entire production cycle. In addition， more studies are needed to refine region-specific emission factors. For greenhouse gas mitigation， efforts should focus on improving dietary formulations， integrating farm management， and implementing genetic selection programs to promote the sustainable development of ruminant livestock production.

Key words: Rumen, Livestock, Ruminants, Greenhouse gases, Intestinal methane

摘要： 甲烷（CH₄）是第二大温室气体，反刍家畜胃肠道排放贡献了全球人为CH₄排放源的40%，阻碍了国家应对全球气候变暖和“双碳”目标的实现。本文系统归纳发现，CH₄排放量在不同地区、家畜种类以及饲养阶段之间均存在显著差异。温暖湿润地区CH₄排放数值跨度大于寒冷干燥地区；大体型动物排放普遍较高，如水牛繁殖母畜排放高达110.6 kg·头^-1·年^-1，而绵羊和山羊则较低（约12~13 kg·头^-1·年^-1）；不同饲养阶段和方式下排放因子范围在6.5~110.6 kg·头^-1·年^-1。反刍家畜胃肠道CH₄排放测定方法包括：六氟化硫示踪法、呼吸室/面罩法、GreenFeed、体外发酵法、激光技术及模型预测等。减排措施主要包括调整饲粮配比、添加剂、调控瘤胃菌群、免疫法、品种改良、优化管理、靶向抑制产甲烷关键酶、调控氢代谢分流及基因编辑重塑瘤胃。未来研究应着重于建立反刍动物全生产周期的甲烷排放精准核算体系，细化不同地区甲烷排放因子，减排可主要从改善饲粮组成、结合牧场管理和遗传选育入手，以推动反刍家畜生产可持续发展。

关键词: 瘤胃, 家畜, 反刍动物, 温室气体, 肠道甲烷