Abstract Livestock production is one of the main contributors to global greenhouse gas (GHG) emissions. The tools provided by the Intergovernmental Panel on Climate Change to estimate GHG emissions (Tier 1 and Tier 2) cannot be used as a tool for advising farmers or national policy on how to minimize GHG emissions because these estimates are not explicitly related to any metabolic properties. For that, we need a metabolic model that obeys mass and energy balances and that models the trade-offs between different allocations of energy in the organism, throughout the life-cycle, as a function of environmental variables such as temperature and the amount and type of food. The Dynamic Energy Budget (DEB) Theory ensures mass conservation and models the transformations of state variable and product formation, allowing for explicit GHG emissions estimates. Therefore, we used this theory to build models for four bovine breeds – Alentejana, Angus, Charolais and Limousin. The goodness-of-fit of DEB models to data is good for all breeds. Differences in DEB breed specific parameters, such as the maximum reserve density and the maximum specific assimilation rate, explain differences in GHG emissions, ultimate lengths and weights and von Bertalanffy growth rates. Accumulated methane and nitrogen production ranges between 0.2 and 2, and 0.1 and 0.7 kg per kg of body weight, respectively. In terms of accumulated direct GHG emissions, there is a strong dependence on breed and age.

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最大限度地减少畜牧生产中的直接温室气体排放：代谢理论的必要性

摘要 畜牧生产是全球温室气体 (GHG) 排放的主要贡献者之一。政府间气候变化专门委员会提供的估算温室气体排放量（第 1 层和第 2 层）的工具不能用作就如何最大限度地减少温室气体排放向农民或国家政策提供建议的工具，因为这些估算与任何代谢特性没有明确关系. 为此，我们需要一个代谢模型，该模型遵循质量和能量平衡，并模拟生物体在整个生命周期中不同能量分配之间的权衡，作为环境变量（如温度、数量和类型）的函数的食物。动态能量收支 (DEB) 理论确保质量守恒并对状态变量和产品形成的转换进行建模，从而允许明确的温室气体排放估算。因此，我们使用这一理论为四种牛品种——阿连特贾纳、安格斯、夏洛莱和利穆赞建立了模型。DEB 模型对数据的拟合优度对所有品种都有好处。DEB 品种特定参数（例如最大储备密度和最大特定同化率）的差异解释了温室气体排放、最终长度和重量以及 von Bertalanffy 增长率的差异。累积的甲烷和氮气产量分别在每公斤体重 0.2 和 2 公斤以及 0.1 和 0.7 公斤之间。就累积直接温室气体排放而言，对品种和年龄有很强的依赖性。例如最大储备密度和最大比同化率，解释了温室气体排放、最终长度和重量以及冯·贝塔朗菲增长率的差异。累积的甲烷和氮气产量分别在每公斤体重 0.2 和 2 公斤以及 0.1 和 0.7 公斤之间。就累积直接温室气体排放而言，对品种和年龄有很强的依赖性。例如最大储备密度和最大比同化率，解释了温室气体排放、最终长度和重量以及冯·贝塔朗菲增长率的差异。累积的甲烷和氮气产量分别在每公斤体重 0.2 和 2 公斤以及 0.1 和 0.7 公斤之间。就累积直接温室气体排放而言，对品种和年龄有很强的依赖性。