Effect of Bacillus subtilis and Bacillus licheniformis probiotic supplementation on cecal Salmonella load in broilers challenged with salmonella

The overall objective in this study is to determine the effects of Bacillus subtilis and Bacillus licheniformis probiotic supplementation on performance and cecal Salmonella load in broilers challenged with Salmonella enterica serovar enteritidis. A total of 360 one-day-old broiler chicks were randomly distributed to 4 experimental groups in a 2 × 2 factorial setup of treatments: control, control + challenge, probiotics (10 mg/kg feed of B. subtilis strain HU58; HU58 plus 100 mg/kg feed of B. licheniformis SC307; Prepro; Microbiome Labs, Saint Augustine, FL), and probiotics + challenge. Each treatment was replicated in 6 pens (n = 6) with 15 chicks per pen. At 21 d of age, all birds in the challenge groups were inoculated orally with 250 μL of 1 × 109 cfu S. enteritidis. At 42 d of age, birds in the control + challenge group had 180-g decrease, whereas birds in the probiotic + challenge groups had only 40-g decrease in the BW gain, compared with the control group. At 28 d of age, birds in the control + challenge group had 220-g decrease, whereas birds in the probiotic + challenge groups had only 140-g decrease in feed consumption compared with that in the control group. Birds in the probiotic + challenge group had 0.73, 1.59, and 1.32 log decrease in Salmonella cfu/g of cecal contents at 5, 12, and 21 d after Salmonella infection, compared with the challenge group. Birds in the challenge group had higher (P < 0.05) titers of anti-Salmonella IgA in the bile. Birds in the probiotic + challenge group had further increased (P < 0.05) anti-Salmonella bile IgA titers compared with the birds in the challenge group. At 21 d after Salmonella infection, birds in the challenge group had 17.3-μm decrease (P < 0.05) in the villus height compared with the control group, whereas birds in the probiotics + challenge group had a comparable villus height to that in the probiotic group. It can be concluded that B. subtilis and B. Licheniformis probiotic can be a tool in decreasing Salmonella loads in the broiler's gastrointestinal tract, and B. subtilis and B. Licheniformis supplementation can be expected to decrease broiler carcass contamination with Salmonella.