The effects of castration on the quality of black Tibetan sheep meat and muscle metabolites.

Castration is a vital technical practice in Tibetan sheep farming on the Qinghai-Tibet Plateau. It reduces fighting among rams, making it easier to manage the herd while they are grazing. However, the impact of castration on the quality of Tibetan sheep meat and muscle metabolites is unclear at present. On this basis, this study examined differences in meat quality and metabolites between castrated (BTC) and non-castrated (BTN) Black Tibetan sheep using targeted and non-targeted metabolomics. Compared with the BTN group, the meat from the BTC group showed reduced drip loss and increased cooking loss, as well as higher levels of elasticity, chewiness and cohesiveness (P < 0.05). The levels of 11 amino acids, total amino acids, total umami amino acids, 23 fatty acids, SFA, PUFA and MUFA were significantly higher in the BTC group than in the BTN group (P < 0.05). A total of 34 differentially abundant metabolites were identified between the two groups, with uric acid, vitamin C, malate, glutamine and oleic acid being all upregulated in BTC. Purine metabolism, metabolic pathways, bile secretion, the phosphotransferase system, glyoxylate and dicarboxylate metabolism, pyrimidine metabolism, and ABC transporters were the key metabolic pathways associated with meat quality in the castrated group. In conclusion, there are certain differences in meat quality and muscle metabolites between BTC and BTN. Castration can affect meat quality characteristics to a certain extent.