This experiment was conducted to investigate the effects of dietary energy on antioxidant capacity, liver glucose–lipid‐related gene expressions and meat fatty acid of Holstein bulls. Thirty‐six Holstein bulls (age, 17.0 ± 0.49 months; body weight, 493.3 ± 39.7 kg) were randomly allocated to three dietary treatments. The metabolizable energy of diets was 10.12, 10.90 and 11.68 MJ/kg. Bulls in each dietary treatment were sampled at the age of 20, 23 or 26 months. Results showed that serum glutathione peroxidase and superoxide dismutase decreased with the increasing age. Dietary energy and age had interaction effects on the expressions of fatty acid synthase, peroxisome proliferator‐activated receptor alpha, acyl coenzyme A oxidase 1 and carnitine palmitoyl‐transferase 1 alpha. Besides, the increase of age and dietary energy increased the expression of liver phosphoenolpyruvate carboxykinase 1. The expressions of liver glucose‐6‐phosphatase, tumour necrosis factor alpha and sterol regulatory element binding protein 1 increased with the increasing age. The increase of age and dietary energy increased the proportions of C18:1cis‐9, C18:2n‐6trans and monounsaturated fatty acid. In summary, the increase of age and dietary energy enhanced the intensity of metabolic changes and inflammatory responses. Dietary energy and age affected the expressions of liver lipid metabolism‐related genes, further affected meat fatty acid composition of Holstein bulls.

中文翻译：

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日粮能量对不同年龄荷斯坦公牛抗氧化能力、糖脂代谢和肉脂肪酸谱的影响

本实验旨在研究日粮能量对荷斯坦公牛抗氧化能力、肝脏糖脂相关基因表达和肉脂肪酸的影响。36 头荷斯坦公牛（年龄，17.0 ± 0.49 个月；体重，493.3 ± 39.7 kg）被随机分配到三个饮食治疗组。日粮的代谢能分别为 10.12、10.90 和 11.68 MJ/kg。每种饮食处理中的公牛在 20、23 或 26 个月大时取样。结果显示血清谷胱甘肽过氧化物酶和超氧化物歧化酶随着年龄的增长而降低。膳食能量和年龄对脂肪酸合酶、过氧化物酶体增殖物激活受体α、酰基辅酶A氧化酶1和肉碱棕榈酰转移酶1α的表达有交互作用。除了，随着年龄的增加和膳食能量的增加，肝脏磷酸烯醇丙酮酸羧激酶1的表达增加。肝脏葡萄糖-6-磷酸酶、肿瘤坏死因子α和甾醇调节元件结合蛋白1的表达随着年龄的增加而增加。年龄和膳食能量的增加使C18：1的比例增加cis -9、C18:2n-6反式和单不饱和脂肪酸。总之，年龄和饮食能量的增加增强了代谢变化和炎症反应的强度。日粮能量和年龄影响肝脏脂代谢相关基因的表达，进而影响荷斯坦公牛的肉脂肪酸组成。