Effects of dietary macleaya cordata extract on the antioxidant defense, immune function, and intestinal health in Sichuan White Geese.

With increasing restrictions on the use of antibiotics in animal feed, plant-derived feed additives are being used as potential alternatives in poultry production. Macleaya cordata extract (MCE) has antioxidant and immunomodulatory activities, but its effects in geese remain unclear. This study evaluated the effects of dietary MCE on antioxidant capacity, immune function, intestinal morphology, and cecal microbiota in Sichuan White geese. Geese were randomly divided into a control group, a chlortetracycline group, and a MCE group (400 mg/kg) for a 21-day feeding period. Compared with the control group, MCE increased serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, glutathione (GSH) content, and catalase (CAT) activity and reduced malondialdehyde (MDA) concentrations (P < 0.05), whereas protein carbonyl and 8‑hydroxy-2'-deoxyguanosine levels were unchanged. MCE also increased splenic expression of heme oxygenase-1 and superoxide dismutase 1, and decreased the expression of interleukin (IL)-6, IL-8, IL-23, Toll-like receptor 2, and Toll-like receptor 4, and increased IL-10 and IL-13 expression. Dietary MCE increased villus height and the villus height-to-crypt depth ratio in the duodenum, jejunum, and ileum without affecting crypt depth. It also increased jejunal zonula occludens-1 immunostaining and upregulated the mRNA expression of tight junction-related genes in the jejunum and ileum. Cecal microbiota analysis showed changes in microbial community structure, which were associated with antioxidant activity, immune indices, and barrier-related proteins. Therefore, dietary supplementation with MCE may improve antioxidant defense and modulate immune-related gene expression in Sichuan White geese. It may also support intestinal health, as suggested by changes in intestinal morphology, tight junction-related markers, and the cecal microbiota.