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Control of Salmonella and Other Pathogens of Public Health Concern on Ontario Pig Farms


We propose to conduct field studies on Ontario pig farms in order to establish effective intervention strategies to minimise the prevalence of pathogens of public health significance. In particular, we hope to demonstrate how Yersinia enterocolitica and Salmonella sp can be controlled. These two disease agents appear to be the most important food-borne pathogens associated with pork. If these organisms can be reduced at the farm level then the risk through the rest of the food chain will be also lessened.
Over the past 5 years, we have monitored approximately 80 finishing herds on an annual basis and have identified herds with a high prevalence to either Yersinia or Salmonella. In the case of Yersinia, a major risk factor appears to be environmental contamination and we hypothesised that strict hygiene and reduced mixing of pigs will greatly reduce the prevalence of Yersinia enterocolitica. On the other hand, Salmonella appears to be more closely associated with feeding techniques. We have shown that farms using fermented liquid-feeding are much less likely to have Salmonella-shedding market hogs compared to farms using dry-feeding. It has been suggested that the main reason for this apparent protection is the acidification of the diet. Whereas, liquid feeding is an expensive technology that tends to be only available to large farming operations, water acidification is easily applied to any size of pig farm, making it a more acceptable approach.
We propose to select 10 farms that we have identified as having a high prevalence of Salmonella and another 10 farms that have a high prevalence of Yersinia. Initially, we will investigate the spread of disease within each farm to determine when pigs appear to become infected and therefore determine at which stage of production intervention would be most appropriate. We will conduct field trials to evaluate intervention strategies on 5 farms with Salmonella and 5 farms with Yersinia.
Intervention on five Salmonella farms will consist of water medication with an acidifier. For five Yersinia farms, intervention will be improved hygiene and control of mixing of pigs. Ten control and ten treatment pens will be assigned and followed from entry in the grower-finisher barn until market on each farm. Culture of faeces of market age pigs will be used to determine the success of the treatment.

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Expected Impact of Project Outcomes on Food Safety in Ontario:

Pork production is a major agricultural industry in Ontario and food safety has become an important issue with regard to ensuring both domestic and export markets. Countries, such as Denmark, have instituted on-farm monitoring programs to measure the prevalence of Salmonella. There will be pressure to institute similar programs in Ontario. The success of a monitoring program depends on whether or not farms that are identified with a high pathogen load can be instructed as to how they might be able to reduce the prevalence of Salmonella or other pathogens. At present, it is unlikely that some of the steps used in Denmark and elsewhere could be easily implemented or would be successful.
The Ontario pork industry is very diverse with many different farm types and management systems. In order to be able to implement a program to minimize pathogens of public health concern, intervention strategies need to be relatively inexpensive and practical for small farming operations as well as large multi-site co-operatives. The benefit of this research is to ensure that Ontario pig farmers are able to respond to demands and pressures in the area of food safety. Our goals are to develop the monitoring tools and practical intervention strategies to assist Ontario pig farmers to meet food safety standards of the future.
<P> For more information, please visit the <a href="; target="_blank">Ontario Ministry of Agriculture, Food & Rural Affairs (OMAFRA) Food Safety Research Program</a>.

Friendship, Robert
University of Guelph
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