Comparative Hepatic Transcriptomic Analysis Reveals Metabolic Regulatory Differences Between Qilian and Oula Sheep

Qilian sheep are an important indigenous Tibetan sheep breed adapted to cold and hypoxic environments. To explore hepatic nutrient metabolism in Qilian sheep, this study compared liver transcriptomic profiles between Qilian sheep and Oula sheep raised under similar natural grazing and management conditions. Six 10-month-old ewes from each breed were selected, and three high-quality liver RNA samples from each group were used for transcriptome sequencing. A total of 1640 differentially expressed genes were identified using the thresholds of |log2FoldChange| > 1 and false discovery rate < 0.05, including 922 upregulated and 718 downregulated genes in Qilian sheep compared with Oula sheep. KEGG enrichment analysis showed that these genes were mainly associated with lipid metabolism, amino acid metabolism, the PPAR signaling pathway, fatty acid biosynthesis, and fatty acid β-oxidation. qRT-PCR validation confirmed the differential expression of 11 candidate genes, including RGN, LPGAT1, BHMT2, SDS, GK, PC, MIOX, HMGCS2, PNPLA3, ACAA2, and HADHA. These results suggest that Qilian sheep and Oula sheep differ in hepatic gene expression patterns related to lipid utilization, amino acid metabolism, and energy regulation, providing candidate genes and pathways for understanding breed-associated hepatic metabolic characteristics.