Allium mongolicum Regel Ethanol Extract Remodels Plasma Metabolome and Lipid Metabolism While Modulating Milk Metabolite Profiles in Dairy Cows

Blood metabolism in dairy cows is crucial for milk quality, functioning primarily through the “blood–milk” metabolic axis. Allium mongolicum Regel (AMR), a functional Allium herb, has been shown to regulate on ruminant lipid metabolism. This study investigated the impact of AMR ethanol extract (AME) on lactation performance, blood lipid parameters, and blood–milk metabolomes. Twelve mid-lactation Holsteins (606 ± 11 kg; milk yield 33.14 ± 2.08 kg/d) of parity 2–3 were assigned to either a basal diet (CON) or a diet supplemented with 54 g/d of AME (AEE). Results indicated that AME significantly decreased plasma triglycerides (TG), C15:0, C16:1, C18:1 n-9 c, C18:3 n-6, monounsaturated fatty acids (p 0.05). Metabolomic profiling revealed that AME significantly enriched the glycerophospholipid metabolism pathway in plasma, upregulating key phospholipid precursors such as L-serine and Sphinganine. Concurrently, milk metabolomics showed an upregulation of short-chain Acylcarnitines. Plasma TG correlated negatively with both plasma L-serine and milk Acylcarnitines, whereas low-density lipoprotein correlated positively with these energy-driven milk metabolites. These findings suggest that AME may contribute to remodeling the plasma lipid metabolic profile in a manner that could facilitate plasma-to-milk lipid flux. This appears to occur through enhanced hepatic lipid processing and increased mammary lipid utilization, offering preliminary insights into potential nutritional strategies for supporting lipid metabolism in dairy cows.