Investigating farm-level risk factors for Salmonella Dublin infection and on-farm transmission in British Columbian dairy farms

A recent study found that 30% of all dairy farms in British Columbia (BC) were positive for <i>Salmonella</i> Dublin, which has prompted a need to determine how to properly manage and mitigate <i>Salmonella</i> Dublin within the province. The overarching goal of this study is to use the components of a Danish <i>Salmonella</i> Dublin risk scoring tool to perform a cross-sectional, exploratory study to evaluate whether the tool, or components therein, can differentiate between <i>Salmonella</i> Dublin bulk tank milk (BTM)-positive versus BTM-negative BC dairy farms. A total of 70 BC dairy producers completed the survey and were classified as positive or negative based of BTM surveillance results. Overall, the components outlined in the modified Danish tool failed to differentiate herds that were positive or negative for <i>Salmonella</i> Dublin on BTM, with only 2 risk factors being identified. Farms that reported housing more than one adult dairy cow in the maternity pen were 4 times more likely to be positive for <i>Salmonella</i> Dublin on BTM than farms that only kept one adult in the maternity pen at a time. Future research should seek to determine if further modifications to the risk factor survey would be useful, especially the inclusion of questions on factors that target introduction of <i>Salmonella</i> Dublin versus on-farm transmission of <i>Salmonella</i> Dublin.