摘要Diarrhea is the leading cause of mortality in postnatal goat kids,seriously impacting breeding efficiency.This study aimed to explore the effects of Bacillus pumilus 315(B.pumilus)on goat kids'diarrhea and its regulatory mechanism.Thirty-six 1-day-old goat kids were assigned into four treatments,the control(CON)group and low-,medium-and high-dose groups supplemented with B.pumilus at 1 × 108(BP1),5 × 108(BP5),and 1 × 109 CFU/d(BP10).Each group consisted of 9 replicates with 1 goat kid per replicate.The results showed that the incidence of diarrhea and fecal scores decreased significantly(P＜0.05).A dose of 5 × 108 CFU/d B.pumilus reduced pro-inflammatory factors(including tumor ne-crosis factor-α[TNF-α],interleukin-1 β[IL-1β],interleukin-6[IL-6],P＜0.05),increased the expression levels of anti-inflammatory factors(including transforming growth factor-β[TGF-β],peroxisome proliferate-activated receptor-gamma[PPAR-y],interleukin-10[IL-10],P＜0.05),immune indicators(including immunoglobulin G[IgG],immunoglobulin A[IgA],immunoglobulin M[IgM],secretory immunoglobulin A[sIgA],P＜0.05)and antioxidant indicators(including total antoxidative capacity[T-AOC],superoxide dismutase[SOD],glutathione peroxidase[GSH-Px],catalase[CAT],P＜0.05)in both jejunum and colon,and ultimately improved the barrier function of the jejunum and colon mucosa.The enhanced gut immunity and barrier function were associated with increased abundance of Enterococcus and Lactobacillus(P＜0.05)and decreased abundance of Campylobacter and Escherichia-Shigella(P＜0.05).In conclusion,dietary addition of B.pumilus may improve gut health by modulating the composition and function of the flora,ultimately alleviating diarrhea in goat kids.