HORIZONTAL TRANSMISSION OF SALMONELLA-TYPHIMURIUM IN BROILER CHICKS

Broiler breeder flocks and hatcheries have been identified as reservoi rs of salmonellae and potential sources of Salmonella infection for hi ghly susceptible day-old chicks. Once salmonellae have colonized the g astrointestinal tract of the chick, the bacteria replicate and are she d into the environment to contaminate it and to colonize other chicks. Salmonella will continue to cycle throughout the broiler flock via bi rd to bird contact, and any facilities that have housed the flock will become a potential reservoir for future flocks. The present studies w ere conducted to evaluate horizontal transmission of Salmonella typhim urium from challenged chicks (seeders) to non-challenged broiler chick s (contacts). Data from the present study suggest that the spread of S almonella from seeder chicks to contact chicks is dependent on the Sal monella challenge dose and not the number of chicks originally exposed . Horizontal transmission of Salmonella to unchallenged contact chicks from seeders initially challenged with 100 Salmonella or more will li mit the effectiveness of any post-hatchery Salmonella control program after they leave the hatchery.