Purpose: The purpose of this study is to help understand prevalence in the cow/calf operations in the Southwest U.S.
Methods: Thirty cow/calf pastures were investigated during this experiment. From each cow/calf pasture fifteen fecal samples, three water, three swab and three sediment samples were tested for Salmonella and Escherichia coli O157:H7. Samples were collected from most ranches twice in the Summer and Fall months of 2011. Sampling supplies were shipped from Texas Tech University to cow/calf operations with instructions to obtain samples and shipped back in cold conditions to TTU for microbial analysis. Salmonella and E. coli O157:H7 were detected in water samples using PCR analysis with the BAX system. Fecal and sediment samples were tested for Salmonella presence by enriching samples in RV and TT for 24 hours at 42°C and plating on XLT-4. Fecal and sediment samples were tested for E. coli O157:H7 using IMS protocols and biochemical confirmation.
Results: During summer sampling, fecal samples were 4.8% positive for E. coli O157:H7 (n=900) and 5.8% positive (n=450) for Salmonella. Salmonella and E. coli O157:H7 were not detected in water samples in the fall or summer. E. coli O157:H7 was not detected in any swab sample and only 1.1% of swab samples (n=90) were positive for Salmonella. Sediment samples were 2.2% (n=90) positive for Salmonella and 0.002% positive for E. coli O157:H7 (n=180).
During fall sampling time, fecal samples were 1.1% positive (n=900) for E. coli O157:H7 and 3.33% (n=450) positive for Salmonella. Swab samples were all negative for both pathogens. Sediment samples were 1.1% positive for Salmonella and 0% positive for E. coli O157:H7.
Significance: While the prevalence of pathogens were low in cow/calf operations in the Southwest, more data are needed over various years and different geographical locations to gain more understanding of the behavior of pathogens in these environments.