反刍家畜及其排泄物对N2O和CH4排放的贡献

Contributions of ruminants and their excreta to N_2O and CH_4 emissions

了解反刍动物及其排泄物对温室气体的贡献以及主要影响因素对于认识全球气候变化及寻找减缓措施都具有重要的社会、经济和生态学意义。本文在综述了大量国内外相关文献的基础上,提出提高家畜营养水平和均衡营养,特别是在天然草原上增加豆科牧草的比例,并通过在饲料中适量添加中链脂肪酸等添加剂,是提高家畜的生产性能、降低CH4排放量的有效措施。同时指出,由于在家畜排泄物处理和利用过程中,降低一种温室气体的排放可能会增加另一种气体的排放,因此,应该根据它们对大气增温潜值的差异,将各种处理下温室气体换算成CO2-C,从而进行比较分析,通过调整综合措施以达到二者总释放量的最低水平;同时还应该考虑到所产生的NH3和亚硝酸盐/硝酸盐对大气和环境的污染。因此,如何提高反刍家畜的饲养与营养、调整放牧管理制度、改善草原群落结构,从而在提高个体生产性能的基础上达到降低家畜总饲养量,最终实现草原生态保护、家畜生产和温室气体排放综合考虑的折衷管理方案,是今后所要解决的科学问题。任何减缓温室气体排放的措施都应该以整个生产系统为基础,从而综合评价所采取措施的有效性。

To clarify the contributions of ruminants and their excreta to greenhouse gases emission and the main affecting factors is of social, economic, and ecological significances for understanding the global climate change and searching for related mitigation options. Based on the related researches, it was considered that to improve the dietary quality and nutritional balance of ruminants （e. g. , to add additives medium-chain fatty acid and others into diets and to increase the proportions of leguminous grasses in grassland） could be the effective measures in enhancing ruminant productivity while decreasing CH4 emission. The contributions of ammonia, nitrite, and nitrate produced by the ruminants and their excreta should be also paid attention to. As the decrease of a kind of greenhouse gas emission could result in the increase of another kind of greenhouse gas emission during the storage and utilization of ruminants＇ excreta, the total emission of the greenhouse gases should be regulated by integrative measures, according to the warming potential of the gases calculated as CO2-C. Therefore, how to improve the feeding and nutrition of ruminants through adjusting grazing management regime and plant community structure in grassland would be the scientific issue to be solved in the future to realize the balance between the ecological conservation of grassland and the reduction of greenhouse gase emissions per unit ruminant production.