奶牛围产期时大量非酯化脂肪酸（NEFA）动员入血，部分可进入骨骼肌代谢。然而，围产期高血NEFA时，骨骼肌脂肪酸未能完全氧化，可诱发代谢疾病。基于前期工作，我们推测，高NEFA可能经干扰从脂肪酸转运到呼吸链的某个/某些代谢步骤，继而阻碍脂肪酸氧化利用。为验证该假设，本课题首先通过体内试验，明确奶牛围产期高血NEFA时脂肪酸组分变化的一般规律；然后，应用奶牛骨骼肌原代细胞培养体系，研究高NEFA对脂肪酸氧化利用的核心细胞器：线粒体及过氧化物酶体的影响；最后，应用靶向代谢组学，并综合荧光定量PCR、Western Blot，多角度协同定位受影响的脂肪酸氧化利用相关代谢路径，力求揭示围产期奶牛高血NEFA阻碍骨骼肌脂肪酸代谢的机制。作为前期研究的延伸，本研究有利于进一步理解骨骼肌响应围产期生理应激的营养生理角色，为保障高产奶牛健康养殖提供理论依据和技术储备。

The transition from late gestation through early lactation in dairy cows is associated with a substantial mobilization of adipose tissue, leading to a marked increase in circulating concentrations of non-esterified fatty acid (NEFA), which are oxidized by hepatic and extrahepatic tissues as an energy source to overcome the negative energy balance in this period. The oxidative capacity for fatty acid (FA) in skeletal muscle, may also contribute to reducing the metabolic load of FA on the liver. Other researchers and we have previously observed incomplete muscle FA oxidation after parturition through an unclear mechanism, which may be associated with the development of metabolism disorders as documented in human studies. Our preliminary results suggest it is likely that dysregulation of fatty acid metabolic pathways, such as fatty acid transport system, beta-oxidation, TCA cycle, and respiratory chain caused incomplete FA oxidation in the skeletal muscle around parturition. The present proposal aims to clarify the mechanism of incomplete skeletal muscle FA oxidation in dairy cows with high plasma NEFA during the transition period. In particular, the following experiments shall be conducted by using qPCR, Western blot, and targeted metabolomics approaches:.1) To evaluate the longitudinal changes of the composition of plasma NEFA in periparturient dairy cows. 2) To examine the effect of high NEFA on mitochondrial and peroxisomal FA metabolism in dairy cow myocytes, and 3) To characterize NEFA-mediated alterations in the FA metabolism in dairy cow myocytes combining targeted metabolomics, qPCR and Western Blot..The expected outcomes from the present proposal are 1) To gain a better understanding of the response and adaptation of skeletal muscle to stress, including high serum concentrations of NEFA during the transition period, and 2) To provide a solid foundation for the benefits of high yielding dairy cows.