Diversity of Salmonella serotypes in cull (market) dairy cows at slaughter

Objective—To determine the diversity of Salmonella serotypes isolated from a large population of cull (market) dairy cows at slaughter. Design—Cross-sectional study. Sample Population—Salmonella organisms isolated from the cecal-colon contents of 5,087 market dairy cows. Procedure—During winter and summer 1996, cecalcolon contents of cull dairy cows at slaughter were obtained from 5 US slaughter establishments. Specimens were subjected to microbiologic culturing for Salmonella spp at 1 laboratory. Identified isolates were compared with Salmonella isolation lists published by the Centers for Disease Control and Prevention (CDC) and the National Veterinary Services Laboratory (NVSL) for approximately the same period. The Simpson diversity index was used to calculate the likelihood that Salmonella isolates selected randomly by establishment were different. Results—Of 58 Salmonella serotypes identified, Salmonella ser. Montevideo was the most prevalent. Two of the top 10 CDC serotypes identified from humans i...