Evaluation of salmonella serotype distributions from commercial broiler hatcheries and grower houses

By conventional trayliner (hatcheries) and drag swab assembly (broiler hous es) culture methods, the isolation distribution of Salmonella serotypes fro m five commercial broiler hatcheries (three sample times) and 13 broiler fa rms (eight. sample times) was evaluated. A total of 11 different Salmonella serotypes were isolated from hatcheries, with Salmonella heidelberg (9/30) and Salmonella kentucky (6/30) accounting for 50% of the total isolations. Of 700 chick paperpad trayliners sampled, regardless of lot (breeder flock source) or hatchery, 12% were positive for Salmonella. When 10 individual trayliners were cultured from individual lots (same breeder flock source), Salmonella was detected in 24/57 lots (42%). Multiple serotypes were simult aneously isolated from the same lot on three occasions (6%). Of the 21 lots that were serially sampled, the Salmonella serotype detected was different within lots eight times (38%) on at least one occasion of two or more samp ling times. Of the 196 individual broiler houses sampled, 44 were positive for Salmonella (42%). Twelve different serotypes were isolated from broiler houses during this study. The serotypes isolated most frequently were S. h eidelberg (34/94) and S. kentucky (22/94). These two serotypes accounted fo r 59.6% (56/94) of the total broiler house isolations. Of the 38 houses tha t were serially sampled, two or more serotypes were detected in the same br oiler house on 20 occasions (53%). Of the 38 serially sampled houses (four or more times), a consistent Salmonella serotype was detected in five house s (13%). In only 5 of the 38 (13%) serially sampled houses did we fail to d etect Salmonella on four or more samplings. No significant difference in Sa lmonella isolation frequency was observed between poultry houses using new or used litter. These data support previous findings indicating that paraty phoid Salmonella serotypes are prevalent in some broiler hatcheries and hou ses. Further, the observation of multiple serotypes simultaneously and seri ally isolated from the same breeder hatchery lots suggests that breeder flo cks may be infected with more than one serotype, possibly providing a sourc e for multiple serotype infections in progeny grower flocks.