FLOCK INFECTION AND TRANSPORT AS SOURCES OF SALMONELLAE IN BROILER-CHICKENS AND CARCASSES

Abstract

Cultural monitoring was used to determine the incidence and sources of salmonellae in a 4160-bird broiler flock raised on litter in 32 pens. Twenty-five of the pens remained apparently free of salmonellae during the 49-day growing period. Salmonella johannesburg, first detected in the meat meal component of the starter ration, was recovered from the litter of 7 pens and from the intestines of dead or culled chicks from 2 pens. S. alachua was also recovered from 2 of these pens. Culture of swabs collected from the plastic crates used to transport this flock for processing showed that 97 of 112 (86.6%) were contaminated with salmonellae (15 serovars) before the birds were loaded. The crate washer at the plant did not remove salmonellae from these crates: 97 of 132 (73.5%) crates sampled after washing yielded salmonellae. Eleven serovars were recovered, including S. johannesburg and S. alachua introduced by the infected flock. Twelve of 31 chickens (38.7%) collected when the birds were unloaded at the processing plant were intestinal carriers of S. johannesburg and/or S. alachua and 29 (93.5%) were external carriers. S. johannesburg, S. alachua and 4 other serovars were isolated from the feathers of these birds. Eleven of 25 (44%) carcasses tested from this flock yielded salmonellae. S. johannesburg or S. alachua, first isolated from the infected flock, were recovered from 5 carcasses and S. haardt and S. typhimurium, first isolated from the transport crates, were recovered from 6 carcasses.