COMPARISON OF SALMONELLA-TYPHIMURIUM CHALLENGE MODELS IN CHICKENS

Experimental infection of chickens with controlled quantities of Salmo nella typhimurium is often achieved by administration of a single oral inoculum of live bacteria to caged chickens. However, this method is a poor simulation of the natural process of S. typhimurium infection i n the field, making the practical application of results obtained unde r such conditions tenuous. This experiment was designed to evaluate th e use of horizontal transmission for the challenge/infection of chicke ns with S. typhimurium with the expectation that it may more closely r esemble the natural situation and, therefore, the in-field physiologic al response of chickens. Further, the experiment allowed for compariso n of both the kinetics and magnitude of the mucosal immune response fo llowing each mode of challenge by exposing the chickens to challenge b y placing them on litter with S. typhimurium-infected seeder birds. Ov erall, birds challenged via seeded litter exhibited a slower rate of i nfection and a more gradual increase in serum antibody production comp ared with birds receiving a single oral inoculum.