The Thai Journal of Veterinary Medicine


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 CEon Salmonellainfectionin 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 107cfu/mL of SalmonellaEnteritidisorally, and were evaluated for 10 days. The CE-treated chickens showed comparable protection andthe 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 administeredby 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 Salmonellacontamination in the farm trial andno Salmonellawas detected in the cecal contents compared with the control group. Average body weight gains, feed conversion ratioand theperformance indexof the chickens were greater than thecontrol group. Thus, the use of CEhad a positive effect on broiler performance. Furthermore, the CE-treated chickens displayed greater intestinal histology including villous height, submuscular layerand cell mitosis.These studies demonstrate that CEwas able to protect chickens from Salmonella cecalcolonization and it is apparent that new methodologies associated with the development of a workable CE program are needed in thepoultry industry.

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