Abstract: The purpose of this study was to explore the key metabolites, metabolic pathways, and enzymes related to the flavor formation of Guyuan cattle beef, so as to lay a foundation for further analyzing the meat quality composition and improving the meat quality of Guyuan cattle beef. In this study, six 24-month-old healthy male Guyuan cattle were collected under the same growth conditions, and non-targeted metabonomics were used to analyze and identify the metabolites of eye meat, shoulder meat and hip meat. The differential metabolites were screened by principal component analysis, partial least squares discriminant analysis and cluster analysis, and the screening results were enriched and analyzed. Subsequently, the pathways and potential key metabolites regulating the synthesis and metabolism of unsaturated fatty acids were analyzed by FELLA, and the differential metabolites were analyzed by WGCNA. A total of 689 metabolites were identified in the eye meat, shoulder meat and hip meat, of which lipids and lipid-like molecules accounting for 32.08%, and 49 fatty acid metabolites. The results of cluster analysis showed that the samples of shoulder meat group and hip meat group were clustered together, while the samples of eye meat group formed a separate cluster. N6, N6, N6-trimethyl-L-lysine and maltotriose were identified as common differential metabolites among eye meat, shoulder meat and hip meat, with the highest content in eye meat. KEGG pathway analysis showed that differential metabolites were mainly concentrated in unsaturated fatty acid biosynthesis, purine metabolism, alanine, aspartic acid and glutamate metabolism. The modules related to three kinds of muscle tissue specificity were screened by WGCNA, and the key metabolites in each module were identified. In this study, through the metabonomic analysis of muscle tissues in different parts of Guyuan cattle, 10 key metabolites and 17 key enzymes related to meat quality differences and flavor formation were identified. It not only provides a theoretical basis for exploring the molecular regulation mechanism and molecular breeding of Guyuan beef flavor formation in the future, but also serves as reference for the quality breeding of other beef cattle.

Key words: Guyuan cattle, non-targeted metabolomics, flavor, unsaturated fatty acids, molecular breeding