消化能和代谢能体系对饲料能值评价存在缺陷，净能体系更能真实的反映饲料的能量利用效率。国外已建立的猪净能体系受限于当地的猪品种和饲料资源，无法完全照搬使用，因此有必要建立我国自己的猪净能体系。在我国生长育肥猪主要饲料原料净能预测方程构建工作基本完成的前提下，研究生长育肥猪的净能需要量是下一步的工作重点。项目组拟采用析因法对杜 × 长 × 大三元杂交生长育肥猪净能需要量进行剖分，利用间接测热试验和消化代谢试验，建立体重和采食量等生长性能参数与净能需要量各因子（维持净能需要，用于蛋白沉积的净能需要和用于脂肪沉积的净能需要）之间的回归方程，从而获得净能需要量预测的动态模型，并且通过大群动物生长试验对预测模型进行验证。研究结果有助于进一步完善我国的猪净能体系，促进精准配方的实现，提高现有饲料资源的利用效率，降低养猪业的生产成本。

When evaluating the energy values of animal feed, the net energy system is better in reflecting the real utilization efficiency of energy contents in feed compared with the digestive energy and metabolizable energy systems. The net energy systems in swine that exist in some European countries are established based on the local breeds of pig and feed. As a result, it is difficult to copy and use these databases in China, and it is necessary to build our own net energy system in swine. The preliminary researches have set up the prediction equations of major feed ingredients in growing-finishing pigs in China, thus the research on net energy requirements in growing-finishing pigs is the emphasis in the next step. This project intends to determine a dynamic model to predict the net energy requirements in Duroc × Large White × Landrace crossbred pigs in growing-finishing phase. The factorial method will be used to divide the net energy requirement into three factors (net energy requirement for maintenance, net energy requirement for protein deposition and for lipid deposition). Indirect calorimetry experiment and digestion and metabolism experiment will be conducted to establish the regression equations between these factors and the growth performance parameters such as body weight and feed intake. The growth trial for large group of animals will be conducted to validate this dynamic model. This project would help to further complete the net energy system in swine in China, promote the realization of precise formulation, improve the utilization efficiency of existing feed resources, and reduce the cost of swine production.