Dietary supplementation with herbal powder of Elsholtzia cypriani improves immune function in Muscovy ducks by activating endogenous antioxidant system and modulating gut microbiota.

Elsholtzia cypriani, a traditional medicinal and edible aromatic plant, exhibits antibacterial, antioxidant, and immunomodulatory properties, making it a promising plant-based feed additive and a potential alternative to antibiotics. However, there is a lack of experimental evidence from case studies. This study investigated the effects of dietary supplementation with E. cypriani on Muscovy ducks. GC-MS analysis identified geranial (45.09 %) and neral (36.29 %) as the principal constituents of E. cypriani essential oil. In vitro bioactivity tests demonstrated significant inhibitory effects against Escherichia coli and Salmonella anatum. A feeding trial was conducted using medium-sized white-feathered Muscovy ducks, with 4 % E. cypriani herb powder added to their diet. The results showed that although growth performance and slaughter rate were not significantly improved, the measure effectively stimulated appetite, leading to increased feed intake and weight gain. It also significantly elevated the thymus index, suggesting it can promote immune organ development. Compared to the control group, dietary supplementation with E. cypriani boosted the systemic antioxidant capacity in ducks, characterized by increased glutathione peroxidase (GSH-Px) activity (p < 0.01) and significantly reduced malondialdehyde (MDA) content (p < 0.001). Furthermore, it considerably improved the inflammatory status, marked by significant reductions in pro-inflammatory cytokines IL-1β, TNF-α, and IL-6 (p < 0.05). Concurrently, in the cecum, supplementation resulted in significantly elevated acetic acid levels and an enrichment of fiber-degrading microbiota such as UBA11471 and Bacteroides H massiliensis. This suggests E. cypriani may promote short-chain fatty acid production by regulating the gut microbiota composition. In summary, E. cypriani enhances the antioxidant and anti-inflammatory capacity of Muscovy ducks by activating the endogenous antioxidant system and modulating gut microbiota, thereby improving overall immune status and production performance. This work underscores the potential of E. cypriani as a natural feed additive and offers insights for developing sustainable alternatives to antibiotics in poultry farming.