Ruminant production systems need to embrace the challenge of reducing greenhouse gas emissions to be in sync with other sectors of society that are adopting net-zero emission goals. The major greenhouse gas from ruminants is enteric methane, which contributes 3% to 5% of total global greenhouse gases. A broad range of potential mitigation strategies has been proposed to decrease methane emissions from ruminants. One promising strategy is the investigational methane inhibitor 3-nitrooxypropanol (3-NOP; DSM Nutritional Products Ltd., Kaiseraugst, Switzerland), which when fed to beef cattle, has decreased methane yield (g methane/kg dry matter intake) by 20% to 80%, depending upon the diet composition and dose. Furthermore, the decrease in methane production persists over several months. 3-NOP reduces methanogenesis in the rumen by inactivating the enzyme methyl-coenzyme M reductase used by archaea. 3-NOP is most effective when incorporated into a total mixed ration. Some advantages of 3-NOP are: only a small dose is required (1–2 g/d); no negative effects on digestibility, animal health or carcass characteristics; rapid degradation to compounds naturally occurring in the rumen (e.g., nitrate, nitrite and 1,3-propanediol); sustained efficacy over time; and risk assessments indicate residues in meat and milk are unlikely. However, 3-NOP is not yet approved for commercial use. Research studies in small pens indicate up to 5% improvement in gain:feed ratio for backgrounding and finishing cattle, although recently completed studies at a commercial feedlot indicate improvements in feed conversion may be less. This presentation will highlight the current findings of beef cattle research using 3-NOP to decrease methane emissions, with emphasis on its potential for decreasing the carbon footprint of beef.

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68 3-NOP 在牛肉生产系统中的效用

反刍动物生产系统需要迎接减少温室气体排放的挑战，以与采用净零排放目标的其他社会部门保持同步。来自反刍动物的主要温室气体是肠道甲烷，占全球温室气体总量的 3% 至 5%。已经提出了广泛的潜在缓解策略来减少反刍动物的甲烷排放。一种有前景的策略是研究性甲烷抑制剂 3-硝基氧丙醇（3-NOP；DSM Nutritional Products Ltd.，Kaiseraugst，瑞士），当喂给肉牛时，甲烷产量（g 甲烷/kg 干物质摄入量）降低了 20% 80%，取决于饮食成分和剂量。此外，甲烷产量的下降持续数月。3-NOP 通过使古生菌使用的甲基辅酶 M 还原酶失活来减少瘤胃中的甲烷生成。3-NOP 加入总混合日粮时最有效。3-NOP 的一些优点是： 只需要小剂量（1-2 g/d）；对消化率、动物健康或胴体特性没有负面影响；快速降解为瘤胃中天然存在的化合物（例如硝酸盐、亚硝酸盐和 1,3-丙二醇）；随着时间的推移持续有效；风险评估表明肉类和牛奶中的残留物不太可能。然而，3-NOP 尚未获准用于商业用途。小型围栏的研究表明，背景和育肥牛的增重：饲料比提高了 5%，尽管最近在商业饲养场完成的研究表明饲料转化率的提高可能较小。