Synergistic Regulation of Selenium Yeast and Vitamin E on the Rumen Microbiota-VFA-Liver Axis in Lambs

Background Lambs in intensive farming face susceptibility to environmental and physiological stress, which can adversely affect their health and growth. Although selenium and vitamin E are recognized for their strong antioxidant and stress-alleviating properties, the combined effects of these substances in ruminants, especially within the regulatory framework of the "rumen-liver" axis, remain inadequately elucidated. This study sought to explore the regulatory pathways within this axis by evaluating lamb growth, immunity, antioxidative capacity, rumen function, liver transcriptome, and their interrelationships. Results The average daily weight gain, growth hormone levels, and immunoglobulin concentrations in the MIX group of lambs were significantly elevated, accompanied by an enhancement in serum antioxidant capacity ( P  < 0.05). Concurrently, the rumen environment was notably improved, as evidenced by a reduction in pH and ammonia nitrogen levels, an increase in volatile fatty acid production, and a rise in the abundance of beneficial bacteria, including Firmicutes and Prevotella. Further analysis of the liver transcriptome indicated that differentially expressed genes were enriched in immune and antioxidant-related pathways, such as arachidonic acid metabolism. Correlation analysis suggested that rumen microorganisms may influence liver gene expression via volatile fatty acid metabolism. Conclusion The combined addition of selenium yeast and Vitamin E to the diet enhances antioxidant and immune capabilities through the "microbiotic-VFA-liver" axis, thereby synergistically improving the growth and health of lambs.