Abstract: 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.

Key words: Age structure, Life table, Survival curve, Environmental factor, Time sequence