High ambient temperature provokes heat stress in animals, and pigs are highly affected showing low performance, and intestinal integrity and microbiota compromised. Probiotics could help pigs to maintain a healthy intestinal environment. We analyzed the effect of a probiotic based on Bacillus subtilis on growth performance, intestinal integrity of small intestine, intestinal microbiota, antioxidant activity, and serum concentration of amino acids in pigs under heat stress (HS) and thermal neutral (TN) conditions. Ambient temperature under TN and HS conditions was 19–25 and 30–38.5 °C, respectively. Weight gain and feed intake reduced in HS pigs compared to TN pigs, but probiotic increased weight gain in both TN and HS pigs. Heat stress decreased villi size in duodenum and jejunum, and probiotic restored them. Relative abundance of Lactobacillus and Bifidobacterium reduced and Escherichia coli increased in the small intestine content of HS pigs; probiotic increased the abundance of Bacillus. The activity of antioxidant enzymes increased in HS pigs fed the probiotic diet. Serum concentration of amino acid metabolites was affected by HS. These data suggest that supplementing a Bacillus subtilis-based probiotic may help to counteract the negative effects of HS on the performance and intestinal integrity of pigs.

Read the full article in the Journal of Animal Science.