Enterococcus faecalis enhances growth and immunity in geese by modulating the jejunal microbiota and intestinal barrier.

The application of Enterococcus faecalis (E. faecalis) in goose farming has been increasing, and it has demonstrated significant efficacy in reducing the diarrhea rate, inhibiting the number of Escherichia coli, and improving production efficiency and feed utilization. This study aimed to explore the effects and mechanisms of E. faecalis on growth, immunity, intestinal barrier, and jejunal microbiota in Zi geese, using network pharmacology and animal experiments. Network pharmacology suggested that metabolites of E. faecalis may regulate pathways related to adherens junction and intestinal immune network for IgA production pathways. Supplementation of drinking water with E. faecalis (1 × 10⁸ CFU/mL) for 48 days significantly enhanced the final body weight, average daily feed intake and average daily gain (P < 0.05) of Zi geese compared to the unsupplemented control group. Serum levels of IgA (P < 0.01) and IgG (P < 0.05) were elevated. In the jejunum, villus height increased and crypt depth decreased (P < 0.01), while mRNA expression of tight junction genes (Claudin-1, ZO-1) and sIgA was upregulated (P < 0.05), and pro-inflammatory cytokine IFNG expression was downregulated. Supplementation with E. faecalis led to a shift in the jejunal microbial community, characterized by a decrease in Proteobacteria and an increase in Firmicutes and Actinobacteria, that was significantly associated with key immune and physiological indices (P < 0.05). In conclusion, E. faecalis improves growth performance by enhancing immunity, intestinal barrier function, and microbial balance, demonstrating its potential as a probiotic feed additive for geese.