能量负平衡是奶牛酮病和脂肪肝发生的中心环节。肝脏和脂肪组织作为脂类代谢的主要器官，脂肪酸氧化状态和能量需要的适应性调节是控制奶牛围产期能量负平衡的关键代谢途径。成纤维细胞生长因子21（fibroblast growth factor-21, FGF21）是最新发现的一种蛋白激素，对人和鼠肝脏中脂肪代谢、糖异生代谢和体内脂肪代谢具有重要和相当特异性的调节功能，能改善机体能量不足。本项目以FGF21在奶牛能量负平衡时具有同样的调节作用为理论假设，运用分子生物学和生物化学技术，通过对未妊娠和未泌乳奶牛在体实验，从肝脏和脂肪组织FGF21及其受体表达以及血液FGF21和重要中间代谢产物水平入手，明确能量负平衡奶牛体内FGF21变化规律，阐明能量代谢特征性指标与体内FGF21之间的关系，揭示FGF21对奶牛能量代谢平衡的调控作用机制，为奶牛能量负平衡提供相应的防治策略奠定理论基础和实践依据

Negative energy balance (NEB) is a common pathlogical foundation of ketosis and fatty liver. Liver and fat tissue are the major organs of lipid metabolism and take part in modulating lipid oxidative capacity and energy demands, which is also a key metabolic pathway that regulates NEB develop during transition period. Fibroblast growth factor-21(FGF21) is a recently discovered protein hormone that plays an importantly and specificly regulating role in adipose lipid metabolism and liver gluconeogenesis for human and mouse. Our aim is to confirm a hypothesis that FGF21 might play the above-mentioned role in dairy cattle with NEB. Non-pregnant, non-lactating dairy cattles will be randomly allocated to our three experimants. By means of molecular biological and biochemical technologies, we will clearly indicate the changed character of FGF21 concentration in blood and gene expression in liver and fat tissue during energy insufficiency, understand a relationship between FGF21 and some characteristic parameters related to energy metabolism in blood, reveal a regulating mechanism of FGF21 on energy balance in dairy cattles. It will be a new theoretical and pratical basis on the preventive strategy of dairy cattle with NEB.