Hepatic antioxidant capacity, immune response, and glycolysis of Tibetan sheep in response to dietary soluble protein levels.

In recent years, the increasing cost of protein raw materials has significantly impacted feed expenses and presented challenges to the livestock industry. Ninety-two-month-old male Tibetan sheep (15.40±0.81 kg) were randomly divided into three groups based on protein levels in their diet: L group (12% protein), M group (14% protein), and H group (16% protein). The feeding experiment was performed for 100 days, including a 10-day adaption period. It was found that the liver cells of the M group exhibited a better uniform in cytoplasm. Additionally, group M sheep had higher levels of GSH-Px and T-AOC (P<0.05), as well as elevated IgM, IL-1β, IL-6, and SDH content compared to other groups (P<0.05). There were 577, 698, and 623 differentially expressed genes between groups H and L, groups H and M, and groups M and L, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the DEGs regulated the activities of 56 pathways. Six liver-metabolism-related DEGs, SOD2, SOD1, CD19, IGF1, HK2, and PFKFB3, were expressed differently among the three sheep groups. In summary, a 14% protein level in the diet improved the hepatic antioxidant capacity, immune function, and glycolysis in Tibetan sheep through modulating the expression of functional genes.