AUTHOR=Guo Mengjiao , Li Mingtao , Zhang Chengcheng , Zhang Xiaorong , Wu Yantao 

TITLE=Dietary Administration of the Bacillus subtilis Enhances Immune Responses and Disease Resistance in Chickens

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01768

DOI=10.3389/fmicb.2020.01768

ISSN=1664-302X

ABSTRACT=<p><italic>Bacillus subtilis</italic> (<italic>B. subtilis</italic>) has a variety of proposed beneficial effects for chickens, including growth promotion and disease prevention. In this study, chickens were fed a diet containing <italic>B. subtilis</italic> for 21 days and growth performance, intestinal morphology, intestinal microbiota, immune responses, and disease resistance were investigated. After 21 days of feeding, chickens fed a diet containing <italic>B. subtilis</italic> had higher body weights. The concentrations of serum immunoglobulins IgA and IgM were significantly increased by <italic>B. subtilis</italic> in the diet. Moreover, chickens fed with <italic>B. subtilis</italic> had greater villus height (VH), shallower crypt depth (CD), and a higher VH/CD ratio in the jejunum than chickens fed a standard control diet. Diet with <italic>B. subtilis</italic> can balance intestinal microbiota, facilitate an increase in beneficial bacteria, and inhibit the pathogenic bacteria after 21 days of feeding. After an <italic>Escherichia coli</italic> (<italic>E. coli</italic>) challenge, the survival rate of chickens fed with <italic>B. subtilis</italic> was 66.67%, which was significantly higher than the controls. The <italic>E. coli</italic> contents in spleens and lungs from chickens fed a diet with <italic>B. subtilis</italic> were lower than those in controls. In addition, <italic>B. subtilis</italic> can trigger the toll-like receptor 4 and cause induction of proinflammatory cytokine (<italic>Il1</italic>β, <italic>Il6</italic>, and <italic>Il8</italic>) production to develop innate immune responses in chickens. In conclusion, diets containing <italic>B. subtilis</italic> can improve growth performance, serum immunoglobulin levels, the intestinal villus-crypt system, intestinal homeostasis, immune responses, and disease resistance against <italic>E. coli</italic> in chickens.</p>