Effects of Bacillus subtilis and coccidiosis vaccine on growth indices and intestinal microbiota of broilers

Avian coccidiosis is the most serious parasitic disease in the poultry industry. Therefore, the aim of the current study was to explore the effects of B. subtilis and live coccidiosis vaccine alone or in combination on the production performance and anticoccidiosis, as well as the dynamic changes of intestinal microbial community. Nine hundred ninty Mahuang chickens were randomized into 4 preimmune groups including control group, coccidiosis vaccine immunization group; B. subtilis administration group and a group that was administrated a combination of live coccidiosis vaccine and B. subtilis group. Intestinal mucosal scraps collected from all these experimental groups at the age of 8 d and 15 d for microbial community 16S rRNA gene sequencing. At the age of 25 d, 30 broilers from each preimmune group were randomly assigned to a subgroup infected with Eimeria spp. and renamed as CI, V-CI BS-CI, and VBS-CI group. The production performance was monitored at the age of 25 d, 35 d, 45 d, and 55 d for the rest broilers from each pre-immune group. Otherwise, in the Eimeria spp. challenge stage, intestinal mucosal scraps collected for microbial community sequencing, while duodenum, jejunum, and cecum collected for pathological examination after sacrifice at the age of 32 d. In addition, the oocysts per gram of feces (OPG) and intestinal lesion score of broilers after Eimeria spp. challenge were also counted. Overall, the probiotics and coccidiosis vaccine resulted in the significantly improvement of the production performance. Otherwise, the intestinal lesion score and OPG after Eimeria spp. infection was significantly decreased in the VBS-CI group (P < 0.05). Moreover, these protective effects may also be closely related to genus such as Romboutsia, Blautia, and Butyricococcus, as well as microbiota functions like the quorum sensing pathway. According to these results, a combination of B. subtilis and coccidiosis vaccines can improve performance and provide additional protection against Eimeria spp. infection.