Background

Higher levels of multi-drug resistant (MDR) Salmonella have commonly been associated with dairy production. This trend has been notable in beef packing plants that process mature cows and bulls. Past research has found higher levels of MDR Salmonella in these facilities, compared to fed beef processing facilities and the higher incident rates of MDR Salmonella are often connected with cull dairy cows.  

The researchers involved in this project have done an extensive amount of sampling for MDR Salmonella in beef primarily from native or beef breeds of cattle. Based on an apparent association between dairy production systems and MDR Salmonella, the researchers hypothesized that Holstein steers might be exposed to MDR Salmonella during the neonatal period (i.e. while at the dairy) or during the growing phase (i.e. while at a calf ranch) and may pose a risk for introducing MDR Salmonella into the fed beef supply. The objective of this project was to evaluate the prevalence and level of MDR Salmonella in Holstein steers, which has never been specifically documented.  

Methodology

Researchers collected hide and fecal samples from Holstein steers and other non-Holstein fed cattle at two large commercial processing plants. Hide samples were obtained by swabbing the same 1,000 cm² area on each animal. Fecal samples were obtained via a rectal swab. Fecal samples were processed for E. coli O157:H7 and Salmonella enumeration and prevalence, while hide samples were processed for Salmonella enumeration and prevalence only. 

Findings

The researchers are performing more detailed analyses, but preliminary data demonstrate that Holstein steers do not carry Salmonella at a higher rate than other fed cattle. Further analyses will be conducted to determine if there is a difference in the proportion of MDR Salmonella between the two groups.  

Implications

Based on the results of this study, Holstein steers do not carry Salmonella at a higher rate than other fed cattle. Further investigation will determine any differences in the proportion of MDR Salmonella between the two groups.