Bacillus subtilis 29784 induces a shift in broiler gut microbiome toward butyrate-producing bacteria and improves intestinal histomorphology and animal performance.

The study reports the effects of Bacillus subtilis 29784 on broiler performance. A total of 1,600 one-day-old Cobb 500 male broiler chicks received either a control diet or the same diet to which B. subtilis 29784 spores were added (1E8 CFU/kg of feed). The birds were slaughtered at 42 D of age. Ileal and cecal tissues and content were collected for histomorphological analysis and 16S rRNA gene sequencing, respectively. The inclusion of B. subtilis 29784 led to an increase of final body weight gain of broilers (+5.7%; P < 0.0001) and an improvement in feed conversion ratio (-5.4%; P < 0.0001). Higher feed efficiency in the Bacillus-fed group was correlated with a significant increase in intestinal microvilli length (+18% in ileum and +17% in cecum; P < 0.001). Among the differences revealed by 16S rRNA analysis, Ruminococcus, Lachnoclostridium, and Anaerostipes were found in higher relative abundance in Bacillus-treated birds at the cecal level. These bacterial genera include species that produce butyrate, the main source of energy for enterocytes and known to be an immune modulator. There was also a slight increase in the Butyrivibrio genus in the cecum, which is known to be an important player in the production of conjugated linoleic acid, also considered an anti-inflammatory compound. In conclusion, dietary supplementation of B. subtilis 29784 significantly improved the growth performance of broilers, likely through beneficial effects on microbiota and host.

Bacillus subtilis strain specificity affects performance improvement in broilers.

The study reports the effects on broiler performance of a newly isolated Bacillus subtilis strain, which is phylogenetically not closely related to already well-described strains of B. subtilis. In the first experiment, birds were reared in battery cages and exposed to C. perfringens. An increase in growth performance was observed with the strain when compared to the challenged animals. Three additional growth trials were conducted to 35 d of age, in different rearing conditions (genetic breeds, corn-soybean meal-based diet with or without animal proteins, in presence or absence of phytase, on fresh or used litter) to investigate the efficacy and the specificity of this new B. subtilis strain on the improvement of BWG and FCR of broilers in comparison with a B. subtilis-based DFM already used in the field. Whatever the rearing conditions tested, the new B. subtilis strain led to an average 3.2% improvement in feed conversion ratio or bodyweight. Comparatively, the commercial Bacillus strain significantly improved broiler performance in only one trial out of 3 with an average improvement reaching 2%. All these results indicate that this new B. subtilis strain consistently improves broiler performances.