Enhanced Antioxidant Activity and Immune Proteins in Donkey Milk from Dietary Selenium Supplementation Revealed by 4D-DIA Proteomics and Metabolomics

This study evaluated the effects of dietary selenium (Se) supplementation on immunoglobulins, lactoferrin (LF), and the antioxidant and immune activities of donkey milk using metabolomic and proteomic analyses. Fourteen lactating donkeys were randomly assigned to the control (basal diet, 0.04 mg of Se/kg of DM) or Se (basal diet + 0.3 mg of Se/kg of DM as selenium yeast) groups for 10 weeks. Se supplementation increased LF and immunoglobulin concentrations, as well as 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radical scavenging activities in whey (P < 0.05). Metabolomic analysis revealed that Se upregulated key metabolites, including niacin and 4-hydroxyphenylpyruvic acid, involved in nicotinate and nicotinamide metabolism and tyrosine metabolism pathways. Proteomic analysis identified differentially abundant proteins, including ceruloplasmin, lipopolysaccharide-binding protein, fatty acid binding protein 4, and interleukin 1 receptor type 1, involved in ferroptosis, NF-kappa B, and PPAR signaling pathways. Overall, Se enhances donkey milk immune and antioxidant activities by modulating its metabolite and protein composition.