Incidence of Salmonella on beef carcasses relating to the US meat and poultry inspection regulations

This article is part of a major study designed to collect baseline contamin ation data by sampling beef carcasses in seven slaughtering plants (four st eer-heifer and three cow-bull plants) during both a dry season (November to January) and a wet season (May to June). Samples (n = 30) were excised fro m each of three carcass anatomical sites (brisket, flank, and rump) at each of three points in the slaughtering chain (pre-evisceration, following fin al carcass washing, after 24-h carcass chilling). A total of 3,780 samples (100 cm(2) each) were analyzed for presence of Salmonella; aerobic plate co unts, total coliform counts, and Escherichia coli counts were also made. Af ter 24-h chilling, average incidence (expressed as a percentage) of Salmone lla in the brisket, flank, and rump samples, respectively, for steer-heifer carcasses was 0.8 +/- 1.7, 0, and 2.5 +/- 5.0 for the wet season and 0.8 /- 1.7, 0, and 0 for the dry season; the corresponding percentages for cow- bull carcasses were 4.4 +/- 2.0, 2.2 +/- 3.9, and 1.1 +/- 1.9 for the wet s eason and 2.2 +/- 3.9, 1.1 +/- 1.9, and 0 for the dry season. Depending on plant and season, ranges of probabilities of chilled steer-heifer carcasses passing the U.S. regulatory requirements for Salmonella contamination were 0.24 to 1.0 for the brisket, 1.0 for the flank, and 0.002 to 1.0 for the r ump; the corresponding ranges for the chilled cow-bull carcasses were 0.25 to 1.0, 0.25 to 1.0, and 0.70 to 1.0. When the number of positive brisket, flank, and rump samples were combined, the probabilities of passing the reg ulatory requirements were 0.242 to 1.0 and 0.772 to 1.0 for the wet and dry seasons, respectively, in steer-heifer plants and 0.368 to 0.974 and 0.865 to 1.0 in cow-bull plants. Correlation coefficients of aerobic plate count s, total coliform counts, and E. coli counts with Salmonella incidence were higher (P less than or equal to 0.05) for cow-bull samples that had increa sed incidence of the pathogen when compared to steer-heifer samples.