Abstract: [Objective] This study was conducted to preliminarily explore the possible regulative mechanisms underlying yellow beef fat of local cattle in Hulun Buir City of Inner Mongolia. [Method] A total of 72 local cattle were selected from Hulun Buir City, and their subcutaneous fat and liver tissues were sampled. The subcutaneous fat samples were subjected to color scoring with a 5-point subjective scoring scheme. Using liver tissues as experimental materials, the penta-primer amplification refractory mutation system （PARMS） was employed to assess the genotype and gene frequency distribution of BCO2 SNPW80X, BCMO1 SNP4, RDHE2 SNP2, ALDH8A1 SNP16 and PPARCG1A SNP12, which were considered as the crucial genes in the signaling pathways involved in the metabolic process of β-carotene. The non-targeted metabolomics analysis of the fat samples were performed by liquid chromatography-mass spectrometry （LC-MS） technology to identify the differential metabolites in different colored fat samples, and the differential metabolites were subsequently subjected to metabolic pathway enrichment analysis. [Result] The 72 subcutaneous fat tissue samples were predominantly white colored, with yellow colored ones （scoring 3 or above） accounting for 30.55%. The SNPs in BCO2, BCMO1, RDHE2 and PPARCG1A genes were observed in different samples, while these SNPs had no significant （P>0.05） correlation with fat color. Compared with the white colored fat samples, a total of 235 differential metabolites were identified in the yellow colored fat samples, which were enriched in the signaling pathways such as unsaturated fatty acid biosynthesis, primary bile acid biosynthesis, and bile secretion. [Conclusion] Comparing the yellow and white colored fat samples collected from the local cattle in Hulun Buir City, there were multiple differential metabolites involving in the signaling pathways closely related to fat formation, in vivo β-carotene transport and trans-membrane transport of β-carotene. In addition, they also directly or indirectly correlated with the β-carotene metabolism associated genes such as BCO2, BCMO1 and PPARCG1A. Further research may focus on the relevant molecular regulatory mechanisms, so as to provide a theoretical basis for the preparation of β-carotene containing feed and the targeted regulation of beef fat color.

Key words: Hulun Buir City, beef cattle, yellow colored fat, SNP, metabolomics, β-carotene