Effect of dietary Bacillus coagulans supplementation on growth performance and immune responses of broiler chickens challenged by Salmonella enteritidis

Abstract

This study was conducted to evaluate the protective efficacy of dietary Bacillus coagulans (B. coagulans) supplementation in birds receiving Salmonella enteritidis (SE). Two hundred and forty 1-day-old Cobb broilers were randomly assigned to 2 × 2 factorial arrangements of treatments with 2 levels of dietary B. coagulans (0 or 400 mg/kg) and 2 levels of SE challenge (0 or 1 × 109 SE between d 9 to 11). Results showed that SE infection did not affect growth performance, but caused intestinal inflammation and barrier function impairment by reducing intestinal goblet cells and beneficial bacteria numbers, increasing cecal Salmonella colonization and liver Salmonella invasion, downregulating jejunal mucin-2 (at 7 and 17 d post-infection, DPI), TLR2 (at 7 and 17 DPI), TLR4 (at 17 DPI), TNFSF15 (at 7 and 17 DPI) gene mRNA levels, and upregulating jejunal IFN-γ mRNA levels (at 17 DPI) compared to uninfected birds. Moreover, SE infection also elevated the concentration of jejunal anti-Salmonella IgA and sera anti-Salmonella IgG compared to uninfected birds. However, chickens received B. coagulans diets showed significant increase in body weight gain and weight gain to feed intake ratio from d 15 to 21, alkaline phosphatase activity (at 7 DPI), cecal Lactobacilli and Bifidobacterium numbers (at 7 DPI; at 17 DPI), villous height: crypt ratio (at 17 DPI), and goblet cell numbers (at 7 and 17 DPI), whereas exhibiting reduced jejunal crypt depth (at 17 DPI), cecal Escherichia coli (at 7, 17, and 31 DPI), and Salmonella (at 7 and 17 DPI) levels compared with the non-supplemented birds, regardless of SE infection. In addition, B. coagulans supplement upregulated lysozyme mRNA levels (at 17 DPI), downregulated IFN-γ mRNA levels (at 7 and 17 DPI), showed an increased trend in Fowlicidin-2 mRNA levels (at 7 DPI) and a reduced trend in liver Salmonella load compared to the non-supplemented control. These data indicated that B. coagulans has a protective effect in SE infected broilers.