Effects of Bacillus subtilis on growth performance, slaughter performance and immune function of broilers

Zhang Jingbo¹, Cheng Peng¹, Zhao Longmei¹, Cao Pinghua¹, Ma Yanbo¹, Fan Shouwu², Li Wang¹
1.College of Animal Science and Technology, Henan University of Science and Technology
2.Luoyang Ouke Biotechnology Co., Ltd.

Abstract: This experiment aimed to study the effects of Bacillus subtilis on the growth performance, slaughter performance, and immune function of broilers. 144 one-day-old (AA) white-feathered broilers (mixed male and female chicks) were randomly divided into three groups, with six replicates per group and eight chicks per replicate. The control group was fed a basal diet (without any additives), the Bacillus subtilis group received a basal diet supplemented with 1.5 × 10¹⁰ CFU/kg Bacillus subtilis, and the antibiotic group received a basal diet supplemented with 300 mg/kg 20% chlortetracycline and 300 mg/kg 20% salinomycin. The experiment lasted for 42 days. The results showed that compared with the control group, the addition of Bacillus subtilis to the broiler diet reduced the average daily feed intake from 1 to 21 days of age (P<0.05), reduced the body weight and average daily weight gain at 21 days of age (P<0.01), and increased the feed conversion ratio (P<0.05) and IgA content (P<0.01). Between 22 and 42 days of age, compared with the control group, the Bacillus subtilis group showed no significant changes in average daily feed intake, average daily weight gain, and feed conversion ratio, but increased thymus index, leg muscle percentage (P<0.05), and IgA and IgG levels (P<0.01). Compared with the antibiotic group, adding Bacillus subtilis to the broiler diet reduced average daily feed intake (P<0.05) and average daily weight gain (P<0.01) at 21 days of age, and reduced IgG levels (P<0.01) at 42 days of age; other indicators showed no significant differences. In conclusion, dietary supplementation with Bacillus subtilis can serve as an alternative to antibiotics in broilers.