Insight into the Meat Quality Characteristics of Tibetan Sheep at Different Age Groups Using Metabolomics

Age-associated variation in Tibetan sheep meat quality and muscle metabolism remains incompletely understood. Eighteen clinically healthy intact male Tibetan sheep were divided into group by age: 6 (M6), 18 (M18) and 42 (M42) months, and their Longissimus dorsi muscles were evaluated for pH, colour, Warner–Bratzler shear force, cooking loss, proximate composition, amino acids, and fatty acids. Volatile compounds were profiled using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry, while muscle metabolites were assessed by untargeted liquid chromatography–mass spectrometry. The results showed that M42 sheep had the highest protein and fat content, as well as the greatest shear force. Notably, levels of monounsaturated and polyunsaturated fatty acids were the highest at M18, yielding distinct flavour profiles and indicating age-associated differences in fatty-acid composition rather than a defined metabolic transition point. Metabolomic analysis identified differential metabolites, primarily enriched in amino acid and lipid metabolism pathways. Correlation analysis revealed that key metabolites, including fumaric acid and linoleic acid, were significantly associated with meat quality parameters. This study elucidates the meat quality characteristics and metabolic basis of Tibetan sheep at different age groups, providing a theoretical foundation for improving meat quality.