This study aimed to comprehensively evaluate the characteristics in the longissimus thoracis et lumborum (LTL) muscle of Chaka (CK) sheep and Tibetan (TB) sheep, and transcriptomics–metabolomics association analysis was used to find the possible genes, differential metabolites, and significant differential metabolic pathways that lead to meat quality differences. Based on the researched results, the nutritional quality of meat, including the contents of ether extract (11.95% vs. 10.56%), unsaturated fatty acid (51.20% vs. 47.69%), and polyunsaturated fatty acid (5.71% vs. 3.97%), were better in TB sheep than in CK sheep, while the CK sheep has better muscle fiber characteristics, such as the total number (62 vs. 45) and muscle fiber density (1426.54 mm² vs. 1158.77 mm²) and flavor. Omics research has shown that the key differential metabolites and metabolic pathways were dominated by amino acid metabolism, particularly the glutathione metabolism, taurine and hypotaurine metabolism, and lipid metabolism-related pathways, such as glycerophospholipid metabolism and the sphingolipid signaling pathway. The intermediate metabolite sn-Glycerol 3-phosphoethanolamine played a key role in determining sheep meat quality, which was regulated by GPAT2, PLPP2, AGPAT1, PNPLA2, and GPAT4 and correlated with meat color, texture, and flavor. Overall, these results will provide effective information and more evidence to support further exploration of valuable biomarkers of meat quality.

Food Science of Animal Resources (Food Sci. Anim. Resour.) is an international, peer-reviewed bimonthly journal publishing original research and reviews on basic and applied aspects of the use of animal resources including the meat, egg, dairy, and edible insect/worm products. Food Sci. Anim. Resour. is published and distributed by the Korean Society for Food Science of Animal Resources.

The flavor of meat significantly influences consumers’ purchasing decisions, with lipids playing a crucial role as precursors in the formation of volatile flavors. In this study, we analyzed the lipids and volatile flavor substances in the longissimus dorsi muscles of Chaka (CK), Black Tibetan (BT), and Oula (OL) sheep by liquid chromatography–electrospray ionization mass spectrometry (LC‐ESI‐MS/MS) and gas chromatography‐mass spectrometry (GC‐MS) techniques. The results showed that the phospholipids PI (13:1_18:1), PI (16:0_16:0), PI (18:0_18:2), PE (18:0_18:3), PE (18:0_20:5), PE (18:1_18:3), PC (13:0_18:0), PC (14:0_18:2), PC (14:0_18:3), and PC (15:0_16:0) were related to the formation of the flavor substances (1.alpha.,4a.beta.,8a.alpha.)‐1,2,3,4,4a,5,6,8a‐octahydro‐7‐methyl‐4‐methylene‐1‐(1‐methylethyl)‐Naphthalene and.gamma.‐Muurolene imparted spicy, herbal and woody sensory properties. The triglycerides TG (10:0_16:0_18:2), TG (12:0_16:0_18:2) and TG (12:0_16:1_18:2) were associated with the formation of acetic acid, 2‐phenylethyl ester and benzenepropanoic acid, methyl ester, which gave the sheep floral, fruity, honey, balsamic, wine, rose and tropical sensory properties. The lipids Carnitine C10:0, Cer (d16:1/24:1), Cer (d18:1/22:1), Cer (d18:1/23:1), and PE (17:0–22:5) were connected to the formation of propylcyclohexane, which provided sheep with sweet, cooked, buttery and meaty sensory characteristics. This study offers insights into the mechanisms of flavor formation in sheep and lays a scientific foundation for the future evaluation and improvement of flavor in different sheep breeds.

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.