Laboratory of Climate Change and Livestock Production, Department of Animal Nutrition, Faculty of Veterinary Medicine and Animal Science, University of Yucatan (UADY), Carretera Merida-Xmatkuil Km 15.5, C.P. 97100Merida, Yucatan, Mexico.
Laboratory of Livestock, Environment and Renewable Energies, Faculty of Veterinary Medicine and Animal Science, University of State of Mexico (UAEM), Instituto Literario 100, C.P. 50000Toluca, Estado de Mexico, Mexico.
Animal. 2020 Sep;14(S3):s453-s463. doi: 10.1017/S1751731120001780. Epub 2020 Aug 18.
Methane (CH4) is a greenhouse gas (GHG) produced and released by eructation to the atmosphere in large volumes by ruminants. Enteric CH4 contributes significantly to global GHG emissions arising from animal agriculture. It has been contended that tropical grasses produce higher emissions of enteric CH4 than temperate grasses, when they are fed to ruminants. A number of experiments have been performed in respiration chambers and head-boxes to assess the enteric CH4 mitigation potential of foliage and pods of tropical plants, as well as nitrates (NO3-) and vegetable oils in practical rations for cattle. On the basis of individual determinations of enteric CH4 carried out in respiration chambers, the average CH4 yield for cattle fed low-quality tropical grasses (>70% ration DM) was 17.0 g CH4/kg DM intake. Results showed that when foliage and ground pods of tropical trees and shrubs were incorporated in cattle rations, methane yield (g CH4/kg DM intake) was decreased by 10% to 25%, depending on plant species and level of intake of the ration. Incorporation of nitrates and vegetable oils in the ration decreased enteric CH4 yield by ∼6% to ∼20%, respectively. Condensed tannins, saponins and starch contained in foliages, pods and seeds of tropical trees and shrubs, as well as nitrates and vegetable oils, can be fed to cattle to mitigate enteric CH4 emissions under smallholder conditions. Strategies for enteric CH4 mitigation in cattle grazing low-quality tropical forages can effectively increase productivity while decreasing enteric CH4 emissions in absolute terms and per unit of product (e.g. meat, milk), thus reducing the contribution of ruminants to GHG emissions and therefore to climate change.
甲烷（CH4）是一种温室气体（GHG），反刍动物会大量向大气中排放。肠道 CH4 是动物农业产生的全球温室气体排放的主要来源。有人认为，热带牧草在反刍动物中产生的肠道 CH4 排放量高于温带牧草。已经在呼吸室和头箱中进行了多项实验，以评估热带植物的叶片和豆荚、硝酸盐（NO3-）和实用牛饲料中的植物油对肠道 CH4 的缓解潜力。根据在呼吸室中进行的肠道 CH4 个体测定，用低质量热带牧草（>70%日粮 DM）喂养的牛的平均 CH4 产量为 17.0 g CH4/kg DM 摄入。结果表明，当将热带树木和灌木的叶片和地上豆荚纳入牛的日粮时，甲烷产量（g CH4/kg DM 摄入）会降低 10%至 25%，具体取决于植物种类和日粮的摄入量。日粮中添加硝酸盐和植物油分别使肠道 CH4 产量降低了约 6%至 20%。热带树木和灌木的叶片、豆荚和种子中所含的单宁、皂苷和淀粉以及硝酸盐和植物油，可以在小规模农户条件下喂养牛，以减少肠道 CH4 排放。在低质量热带草料放牧的牛中减少肠道 CH4 的策略可以在绝对数量和单位产品（如肉、奶）方面有效提高生产力，同时减少肠道 CH4 排放，从而减少反刍动物对温室气体排放的贡献，进而减少对气候变化的影响。
