Evaluation of the Longissimus Thoracis et Lumborum Muscle Quality of Chaka and Tibetan Sheep and the Analysis of Possible Mechanisms Regulating Meat Quality

Simple Summary The quality of mutton is closely related to the development of the entire animal husbandry and sheep industry. The present work quantified the difference in meat quality between Chaka (CK) sheep and (Tibetan) TB sheep through the technology of transcriptomics, combined with metabolomics, to identify genes and metabolites, which are related to meat quality. Our study found that TB sheep have better nutritional value, while CK sheep have better flavor. The GPAT2, PLPP2, AGPAT1, PNPLA2, and GPAT4 genes were identified as key genes that regulate glycerophospholipid metabolism and correlate with meat color, texture, and flavor. Our study comprehensively compared the longissimus thoracis et lumborum (LTL) muscle of CK sheep and TB sheep and explored the difference in meat quality at the molecular level, which may provide a strategy for improving meat quality from a molecular perspective. 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 mm(2) vs. 1158.77 mm(2)) 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.