Milk-based multi-omics reveals distinct quality signatures associated with Astragalus polysaccharide supplementation in late lactation goats
Late lactation is frequently accompanied by changes in goat milk composition and volatile-related quality, which may reduce its commercial value. This study investigated whether Astragalus polysaccharide (APS), a plant-derived bioactive polysaccharide from Astragalus membranaceus (Fisch.) Bunge, is associated with milk quality responses distinct from those induced by probiotic supplementation. Late lactation Saanen dairy goats were assigned to probiotic or APS supplementation for 30 days, and milk samples were analyzed using conventional composition testing, electronic nose (E-nose) profiling, proteomics, untargeted metabolomics, and lipidomics. APS supplementation reduced milk urea nitrogen by 6.20 mg/dL and decreased milk fat percentage, while electronic nose (E-nose) profiling revealed a distinct sensor-level volatile fingerprint dominated by W5S, W2W, and W1S responses. At the molecular level, APS generated a broader metabolomic response than probiotic supplementation, with 904 versus 587 differential metabolites, and was associated with a milk proteomic signature featuring higher ATP citrate lyase abundance (2.52-fold). Lipidomics further showed selective remodeling of milk lipid subclasses, including increased phosphatidylethanolamine, phosphatidylcholine, and ceramide abundance by approximately 1.4-fold, 1.5-fold, and nearly 5-fold, respectively. Together, these milk-based data indicate that APS supplementation was associated with a distinct quality signature involving nitrogen-use indicators, volatile-related sensor profiles, lipid-related protein features, and lipid subclass redistribution. The findings support APS as a potential non-microbial nutritional strategy for modulating late lactation goat milk quality.