Diet-Related Differences Predominate Over Breed-Associated Differences in Hepatic Lipid Metabolism, Antioxidant...

Understanding how nutritional management and genetic background influence hepatic metabolism is important for improving the nutritional quality of bovine products in tropical production systems. This study evaluated breed-associated differences under a common dietary regimen and diet-related differences within the Nelore breed with respect to hepatic cholesterol, lipid-soluble antioxidant vitamins, fatty acid composition and lipid quality indices. Thirty-six intact male cattle were allocated to three experimental groups: Nelore fed a silage-concentrate diet, crossbred (½ Nelore × ½ Angus) fed the same diet, and Nelore fed a high-grain diet. Hepatic cholesterol and antioxidant vitamins were determined by high-performance liquid chromatography, whereas fatty acid composition was analysed by gas chromatography with flame ionisation detection. No significant differences were observed in hepatic cholesterol concentration for either the breed-associated or diet-related contrasts (p > 0.05). Breed-associated differences were detected for β-carotene, β-tocopherol, γ-tocopherol and docosahexaenoic acid (22:6n-3) (p < 0.05). Diet-related differences significantly affected β-carotene, tocopherols, tocotrienols, several individual fatty acids and lipid quality indices, including the n-6/n-3 ratio and hypocholesterolaemic and hypercholesterolaemic fatty acid indices (p < 0.05). Principal component analysis showed clear separation of animals by dietary treatment, with β-carotene, α-tocopherol and tocotrienols contributing strongly to sample discrimination. Overall, diet-related differences within the Nelore breed were associated with significant changes in a broader range of hepatic lipid and antioxidant variables, whereas breed-associated differences under a common dietary regimen were observed for a more limited set of variables. These findings highlight the importance of nutritional management in modulating hepatic composition and support the use of liver biomarkers to assess metabolic responses in beef cattle.