Liver injury threatens the overall health of an organism, as it is the core organ of the animal body. Liver metabolism is affected by numerous factors, with dietary energy level being a crucial one. Therefore, the present study aimed to evaluate hepatic injury and to describe its metabolic mechanism in ruminants fed diets with different dietary energy levels. A total of 25 Yunnan semi-fine wool sheep were fed diets with five dietary metabolic energy levels and were randomly assigned to five groups as follows: low energy (LE), medium–low energy (MLE), medium energy (ME), medium–high energy (MHE), and high energy (HE). The results revealed that the average optical density (AOD) of lipid droplets in the LE, MLE, and HE groups was higher than that in the ME and MHE groups. The enzyme activity of alanine aminotransferase (ALT) was the lowest in the ME group. An increase in dietary energy level promoted the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity and altered the malondialdehyde (MDA) and protein carbonyl (PCO) concentration quadratically. In addition, both high and low dietary energy levels upregulated the mRNA abundance of proinflammatory cytokine interleukin (IL)-1β, nuclear factor-kappa B (NF-κB), and tumor necrosis factor (TNF)-α. Metabonomic analysis revealed that 142, 77, 65, and 108 differential metabolites were detected in the LE, MLE, MHE, and HE groups, compared with ME group respectively. These metabolites were involved in various biochemical pathways, such as glycolipid, bile acid, and lipid metabolism. In conclusion, both high and low dietary energy levels caused hepatic injury. Section staining and metabonomic results revealed that hepatic injury might be caused by altered metabolism and lipid accumulation induced by lipid mobilization.

肝损伤威胁着生物体的整体健康，因为它是动物身体的核心器官。肝脏代谢受多种因素影响，其中饮食能量水平是关键因素。因此，本研究旨在评估不同日粮能量水平的反刍动物的肝损伤并描述其代谢机制。将 25 只云南半细毛羊饲喂具有五种日粮代谢能水平的日粮，并随机分为以下五组：低能（LE）、中低能（MLE）、中能（ME）、中– 高能 (MHE) 和高能 (HE)。结果显示，LE、MLE和HE组的脂滴平均光密度（AOD）高于ME和MHE组。丙氨酸氨基转移酶（ALT）的酶活性在ME组中最低。膳食能量水平的增加促进了超氧化物歧化酶 (SOD) 和谷胱甘肽过氧化物酶 (GSH-Px) 的活性，并以二次方式改变了丙二醛 (MDA) 和蛋白质羰基 (PCO) 的浓度。此外，高和低膳食能量水平均上调促炎细胞因子白细胞介素 (IL)-1β、核因子-κB (NF-κB) 和肿瘤坏死因子 (TNF)-α 的 mRNA 丰度。代谢组学分析显示，与 ME 组相比，LE、MLE、MHE 和 HE 组分别检测到 142、77、65 和 108 种差异代谢物。这些代谢物参与各种生化途径，如糖脂、胆汁酸和脂质代谢。综上所述，高和低膳食能量水平都会导致肝损伤。切片染色和代谢组学结果表明，肝损伤可能是由脂质动员引起的代谢和脂质积累改变引起的。