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Effective control of Salmonella in beef products is needed and pre-harvest intervention
strategies are critical components of an integrated systems approach to ensure beef safety.
Culled cows from the dairy industry contribute substantially to US the beef supply, especially
ground beef products and have often been implicated in Salmonella-positive product. Therefore,
pre-harvest strategies aimed at reducing the burden of Salmonella in these animals is of utmost
concern. Conditionally licensed vaccines hold promise in their ability to increase the effective
immunity of the treated animals against various pathogens including Salmonella. This research
aids in the understanding of herd level factors that are responsible for the Salmonella burden.
<P>
Objectives:<br/>
1. To quantitatively determine whether a commercially available vaccine can effectively
control burden of Salmonella on dairies;<P>
2. To evaluate farm-level variables that explain a
significant amount of variation in Salmonella shedding on dairies; <P>
3. To partition unexplained
variation in Salmonella shedding to within- and between- herd dynamics.
Findings:
Salmonella is ubiquitous throughout the study population and multiple serotypes
previously identified in human outbreaks were identified. However, most isolates recovered
were pan susceptible to a broad range of antibiotics. Additionally, a majority of the observed
variation was within individual herds which in the future may aid in understanding herd-level
drivers responsible for the current Salmonella burden.