Comparing the potential of Bacillus amyloliquefaciens CGMCC18230 with antimicrobial growth promoters for growth performance, bone development, expression of phosphorus transporters, and excreta microbiome in broiler chickens

Bone health of broiler chickens is essential for welfare and production. In this study, the probiotic Bacillus amyloliquefaciens (BA) CGMCC18230 was compared with antimicrobial growth promoters (AGPs) for its ability to promote growth and bone health. To address this, a total of 180 Arbor Acres (AA) 1-day-old, male, broiler chicks were randomly allocated into 3 treatment groups, with 6 replicates, containing 10 chicks in each replicate. The treatment groups were: control group (CON) fed a corn-soybean based diet; BA treatment group fed the basal diet supplemented with 2.5 × 10¹⁰ CFU/kg BA CGMCC18230; AGPs treatment group was fed the basal diet containing the antibiotics aureomycin (75 mg/kg), flavomycin (5 mg/kg) and kitasamycin (20 mg/kg). Over the 42 d experiment, broilers fed BA and AGPs diets both had higher BW, and the ADG was significantly (P < 0.05) higher than that of the CON group both in the grower phase (22–42 d) and overall. Moreover, with BA birds had higher (P < 0.05) serum concentrations of phosphorus (P, day 42) and alkaline phosphatase (ALP, days 21 and 42). Conversely, the content of P in excreta decreased significantly (P < 0.05) on days 21 and 42. Tibia bone mineralization was improved in BA, and the mRNA of P transport related genes PiT-1,2 in the duodenum and jejunum were significantly up-regulated in the BA group than in the CON group (P < 0.05). 16S rRNA gene sequencing revealed that dietary BA supplementation increased the relative abundance of butyrate-producing bacteria (Ruminococcaceae) and polyamine-producing bacteria (Akkermansia and Alistipes), which had a positive effect on bone development. These data show that dietary supplementation of BA CGMCC18320 improves broiler growth performance and bone health similar to supplementation with AGPs through up-regulation of intestinal P transporters, microbial modulation and increase P retention. However, no significant influence of BA CGMCC18320 supplementation on the retention of Ca was found.