Bacillus pumilus 315 improves intestinal microbiota and barrier function to alleviate diarrhea of neonatal goats

Diarrhea is the leading cause of mortality in postnatal goat kids, seriously impacting breeding efficiency. This study aimed to explore the effects of <i>Bacillus pumilus 315</i> (<i>B. pumilus</i>) 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 <i>B. pumilus</i> 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 (<i>P</i> < 0.05). A dose of 5 × 10⁸ CFU/d <i>B. pumilus</i> reduced pro-inflammatory factors (including tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β], interleukin-6 [IL-6], <i>P</i> < 0.05), increased the expression levels of anti-inflammatory factors (including transforming growth factor-β [TGF-β], peroxisome proliferate-activated receptor-gamma [PPAR-γ], interleukin-10 [IL-10], <i>P</i> < 0.05), immune indicators (including immunoglobulin G [IgG], immunoglobulin A [IgA], immunoglobulin M [IgM], secretory immunoglobulin A [sIgA], <i>P</i> < 0.05) and antioxidant indicators (including total antoxidative capacity [T-AOC], superoxide dismutase [SOD], glutathione peroxidase [GSH-Px], catalase [CAT], <i>P</i> < 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 <i>Enterococcus</i> and <i>Lactobacillus</i> (<i>P</i> < 0.05) and decreased abundance of <i>Campylobacter</i> and <i>Escherichia-Shigella</i> (<i>P</i> < 0.05). In conclusion, dietary addition of <i>B. pumilus</i> may improve gut health by modulating the composition and function of the flora, ultimately alleviating diarrhea in goat kids.