Efficacy of competitive exclusion to reduce Salmonella in broiler chickens

Competitive exclusion (CE) relies on the activity of normal flora to limit intestinal colonization by enteric pathogens. This study aims to investigate the effects of CE on Salmonella infection in broilers. The protective effect of CE on Salmonella cecal colonization was evaluated in 1 day-old chicks. In the laboratory trial, CE products were administered by oral inoculation, drinking water and whole body spray. Three days after treatment, the chickens were challenged with 10(7) cfu/mL of Salmonella Enteritidis orally, and were evaluated for 10 days. The CE- treated chickens showed comparable protection and the number of Salmonella in the cecal contents significantly decreased (P < 0.05) compared with those of the positive control. In the farm trial, CE was administered by whole body spray at the hatchery and the second was administered by drinking water and evaluated at 32 and 42 days, respectively. The CE significantly reduced Salmonella contamination in the farm trial and no Salmonella was detected in the cecal contents compared with the control group. Average body weight gains, feed conversion ratio and the performance index of the chickens were greater than the control group. Thus, the use of CE had a positive effect on broiler performance. Furthermore, the CE- treated chickens displayed greater intestinal histology including villous height, submuscular layer and cell mitosis. These studies demonstrate that CE was able to protect chickens from Salmonella cecal colonization and it is apparent that new methodologies associated with the development of a workable CE program are needed in the poultry industry.