Dietary supplementation with Bacillus velezensis enhances the intestinal health of broiler chickens challenged with necrotic enteritis via reshaping the structure and function of the intestinal flora.

Probiotics have great potential in maintaining intestinal health and ensuring the growth performance of broiler chickens, while the effects of Bacillus velezensis (BV) have not yet been fully characterized. In the present study, a necrotic enteritis model was established based on the combined infection of coccidia and Clostridium perfringens (CCP), and the effects of dietary supplementation with BV on growth performance and intestinal health were investigated. Our outcomes showed that dietary supplementation with BV contributed to alleviating the negative effects of CCP on the growth performance. Additionally, the ratio of ileal villus height to crypt depth, the levels of d-xylose and lysozyme in serum, as well as that of secretory immunoglobulin A (sIgA) in ileum were decreased, and the activity of diamine oxidase (DAO) was elevated with CCP challenged (P < 0.05). In addition, the level of ileal malondialdehyde (MDA), transcriptional levels of IL-1β and interferon-γ (IFN-γ) were up-regulated, correspondingly, the ileal total antioxidant capacity (T-AOC) and the mRNA levels of transforming growth factor-β (TGF-β), lysozyme (LYZ), Claudin-1, and Mucin-2 were down-regulated with CCP challenged (P < 0.05). Interestingly, the BV-supplemented diet was able to alleviate the above-mentioned negative effects of CCP on birds. The results of intestinal microbiota sequencing and association analysis further revealed that dietary supplementation with BV helped to enhance the energy utilization efficiency of the intestinal flora and might alleviate the impaired intestinal function of birds challenged with CCP by reshaping intestinal flora, especially through modulating the relative abundance of Clostridium. In conclusion, the diet supplemented with BV enhances the intestinal health of broiler chickens challenged with necrotic enteritis via reshaping the structure and function of the intestinal flora.