Prevalence of Salmonella in beef feeder steers as determined by bacterial culture and ELISA serology

Results are presented for monitoring Salmonella infection by bacteriologica l culture and immune response (enzyme linked immunosorbent assay (ELISA) an d haptoglobin) testing of samples collected from beef cattle at a single fe edyard sampled over time. A total of 120 beef steers were examined on entry to the feedyard and at days 30, 60, and at time of slaughter (120-150 days ). Isolations of Salmonella decreased over time from 40% of the steers samp led at day 0 to 0% at slaughter, whereas serological results varied by sero group. Seropositivity increased for Salmonella group B up to day 60, and su bsequently decreased to about half of the 60-day positivity rate at the tim e of slaughter. No significant changes in seropositivity were detected duri ng the course of the study for the four other Salmonella serogroups (C1, C3 , D1, and El). Haptoglobin measurements were not a good indicator of Salmon ella infection status. Sequential Salmonella testing either by culture, ELI SA, or both could be used to monitor pathogen control practices. (C) 2000 E lsevier Science B.V. All rights reserved.