Intestinal microbiome in necrotic enteritis infection of broiler and comparison of treatment alternatives

Clostridium perfringens is the primary causative agent of necrotic enteritis (NE), a gastrointestinal disease that leads to substantial economic losses in poultry. This study aims to characterize the intestinal microbiome of chickens and assess the effects of Bacillus velezensis on gut microbiota and recovery from necrotic enteritis, comparing its efficacy to antibiotic treatment. The experiment involved five groups, each consisting of 16 chickens. The first group, the start-of-challenge (DB) group, included day-old chicks. The second group, the post-challenge control (DS) group, was reared until the end of the trial. The third group was infected with C. perfringens (NE group). The fourth group received both C. perfringens and B. velezensis (BV group), while the fifth group was treated with C. perfringens and amoxicillin (AB group). All chickens were euthanized via cervical dislocation following the experimental infection. Fecal samples collected from the cecum underwent 16 S rRNA gene-based metagenomic analysis, and the resulting data were statistically evaluated. Macroscopic examination after euthanasia revealed pathological changes in the intestines of chickens in the NE group, which had received only C. perfringens. Their intestines appeared swollen, with slight mild mucosal hemorrhage. In contrast, no macroscopic lesions were observed in the DB, DS, BV, or AB groups. Microbiome analysis showed a decline in microbial diversity within the NE group. The BV group exhibited a microbial composition most similar to that of healthy animals, followed by the AB group. The study concludes that B. velezensis could serve as an alternative to prophylactic antibiotics in mitigating the adverse effects of necrotic enteritis on the gut microbiome.