Immunology, Health, and Disease

The objective of this experiment was to investigate the effects of Bacillus subtilis, yeast cell wall and their combination on intestinal health of broilers challenged by Clostridium perfringens over a 21-d period . Using a 5 × 2 factorial arrangement of treatments, 800 1-d-old male Cobb 500 broilers was used to study the effects of feed additives (without additive or with zinc bacitracin, B. subtilis, YCW, and the combination of B. subtilis and YCW, respectively), pathogen challenge (without or with Clostridium perfringens challenge), and their interactive effects . C. perfringens infection increased broilers’ intestinal lesions scores, damaged broilers intestinal histomorphology, increased the serum endotoxin concentration, cytokine mRNA expression levels and intestinal population of C. perfringens and Escherichia coli, and decreased ileal Bifidobacterium numbers . The 4 additives decreased the serum endotoxin . Zinc bacitracin tended to decrease cytokine mRNA expression levels and the intestinal number of C. perfringens and E. coli . B. subtilis, YCW and their combination increased cytokine mRNA expression . B. subtilis and YCW decreased the number of C. perfringens and E. coli in ileum, and their combination decreased the pathogens numbers in the ileum and cecum . In conclusion, B. subtilis, YCW and their combination improved the intestinal health of NE-infected broilers, and could be potential alternatives of the antibiotics .