DEVELOPMENT AND EVALUATION OF A RAPID TEST PROCEDURE TO DETECT SALMONELLAE IN FEED INGREDIENTS AND FINISHED FEEDS

Broiler, layer, and swine feeds were inoculated with low levels of thr ee Salmonella serotypes commonly found in feed ingredients using a ''c harged'' chalk. The inoculated feeds, noninoculated central feeds, and naturally contaminated poultry byproduct meals were included in an in terlaboratory evaluation of two testing procedures. Three FDA labs, an independent lab, and one university lab were participants in the inte rlaboratory study. A rapid test kit (Salmonella-Tek, Organon Teknika C orp., Durham, NC) was compared to the culture method of Bailey and Cox (1992) which utilizes Universal Preenrichment broth and standard cult ure procedures. Each lab utilized 45 100-g feed ingredient or finished feed samples. There was 89.3% agreement in test results by the five l abs when comparing the two test procedures. The culture method resulte d in 1.3% false negatives while the Salmonella-Tek procedure resulted in 6.2% false positives. Either of the test procedures was capable of detecting extremely low levels (< 5 organisms/100 g) when samples (100 g) were preenriched with Universal Preenrichment broth.