Abstract

Simple SummaryQilian sheep are a local Tibetan sheep breed living in the high-altitude pastoral areas of the Qinghai–Tibet Plateau. Their ability to survive under cold, hypoxic, and seasonally nutrient-limited conditions may be closely associated with special metabolic regulation. In this study, we compared liver gene expression between Qilian sheep and Oula sheep raised under similar grazing conditions. The results showed that the two breeds differed in genes associated with energy use, lipid utilization, and amino acid metabolism. These findings help explain the biological characteristics of Qilian sheep from the perspective of liver metabolism and may provide useful information for the conservation and utilization of Tibetan sheep genetic resources.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, includingRGN,LPGAT1,BHMT2,SDS,GK,PC,MIOX,HMGCS2,PNPLA3,ACAA2, andHADHA. 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 candid