Dietary astragalus crude extracts boost piglet growth and miti-gate weaning stress by enhancing antioxidant activity, im-proving immunity, and modulating intestinal microbiota

Astragalus is a traditional Chinese medicinal that contains various bioactive com-pounds, which exert antioxidant, anti-inflammatory, and immunomodulatory proper-ties. This research aimed to investigate the impacts of astragalus crude extract on growth performance and intestinal health in weaned piglets. Sixty crossbred piglets weaning at 28 d were allocated into three dietary treatments: a control group fed basal diet (CON), an antibiotic group received the basal diet with 1000 mg/kg aureomycin (AN), and a treatment group administered the basal diet with 500 mg/kg astragalus crude extract (CE), with 5 replicates per group, 4 piglets per replicate. Feed intake and body weight were recorded to evaluate growth performance. Blood, intestine, and liver tissue samples were collected for the analysis of antioxidant capacity and gene expres-sion. Compared to the CON group, supplementation with CE or AN significantly en-hanced growth performance and decreased diarrhea incidence on days 0-14, whereas only CE tended to improve crude protein digestibility. Piglets supplemented with AN or CE improved antioxidant capacity and immune response compared to the CON group, as evidenced by increased liver and intestinal antioxidant enzyme activities, upregulated intestinal antioxidant gene expression, enhanced plasma immunoglobulin A levels. Further, the reduced plasma diamine oxidase activity and upregulated intes-tinal tight junction protein expression were observed in CE or AN treatment compared with the CON. Notably, dietary CE significantly modulated gut microbiota composi-tion, particularly enriching the genera Blautia, Turicibacter, Agathobacter, and Clostrid-ium. These microbiome shifts were also significantly correlated with improvements in antioxidant and immune parameters. These findings indicate that dietary astragalus crude extract promotes gut health of weaned piglets by alleviating oxidative stress, at-tenuating inflammatory responses, and modulating gut microbiota composition, thereby reducing diarrhea incidence and improving growth performance.