A pan-Canadian epidemiological observational case-control study of post-weaning diarrhea (PWD) on Canadian swine farms

Why is this project important?

Post-weaning diarrhea (PWD) caused by enterotoxigenic E. coli (ETEC) is one of the major issues for the pork sector, costing the industry an estimated $100 million per year. Pigs are mostly infected a few weeks after weaning, become diarrheic and dehydrated, and sometimes die. Even those who overcome the condition often experience poor weight gain and performance. Cleaning and disinfection between batches and vaccination may help to control the disease. 

Another approach to preventing PWD is the inclusion of antimicrobials in the feed of nursery pigs, but this can lead to antimicrobial resistance to E. coli and other bacteria. While high levels of zinc oxide (2,500ppm) are also used by some producers as a preventive feed additive, this can leave residue in the environment that may pose a public health risk. For that reason, zinc oxide will soon be banned for use in feed.

What will researchers do?

• Visit nursery barns across Canada that have an ongoing or historical issue with PWD associated with ETEC. In each nursery, researchers will select 10 pigs that currently have post-weaning diarrhea (cases) and five healthy pigs (controls) from the same pens, and of the same age, as the sick pigs.

• Seek to understand the type of ETEC that causes PWD in pigs across Canada. Using this knowledge, they will work to develop a more effective vaccine for the disease.

• Gain a thorough knowledge of the gut microbiome in pigs that contract PWD and in those that do not. This will help to identify and/or create probiotics that enhance pig gut health and aid them in combatting PWD.

• Examine genetic resistance in pigs to ETEC F4 and ETEC F18, which are the two most common types of enterotoxigenic E. coli, and screen the pigs’ genomes for genetic markers that affect immune response. The findings will eventually be applied to breed pigs that are resistant to ETEC.

What will be the benefit of this research?

This project will aid producers with not only enhancing profits and productivity, but also improving animal welfare.  By reducing the cost of treatment, researchers can lower expenses on farm. Nursery pigs are very expensive to raise, so having to feed and water them, only to experience death losses or impaired performance, is a significant drain on producer revenue. The current study aims to keep pigs alive and thriving, ensuring that investments in nursery pigs generate the returns needed to protect the producer’s bottom line.

Of great importance is the impact of this work on antibiotic usage. Outcomes that will help to implement more potent vaccines, effectual probiotics and genetic resistance to ETEC all provide healthier alternatives to antimicrobials in protecting nursery pigs. Drawing on the knowledge gained, the swine industry can focus on two key areas: breeding animals that are resistant to the most frequent ETEC and developing probiotics that produce healthier guts.

What has been done so far?

To date, several farms have been visited in Ontario and examined for different types of ETEC. The most prevalent strains so far have been ETEC F4 and ETEC F18, with some farms showing both and others just one of the two. Of note to scientists is that certain pigs who would normally be susceptible to ETEC are not becoming sick. This could be a result of the bacteria passing through them and not attaching to the intestine, or it might be linked to genetics. As well, even some pigs that don’t display PWD are still shedding (replicating or reproducing) the bacteria.

Over the next five years, those on the project plan to sample more farms in Ontario, Quebec, Manitoba, Alberta and Saskatchewan. They will also be working with industry partners including Cargill, OMAFRA (Ontario Ministry of Agriculture, Food and Agribusiness and Ministry of Rural Affairs) and Demeter Services Vétérinaires in Quebec.

Project status: Currently in progress. Results expected in 2028.

Collaborators:

• Dr. Brandon Lillie, University of Guelph

• Dr. Ehsan Khafipour, Cargill

• Dr. John Fairbrother, University of Montreal

• Dr. Robert Friendship, University of Guelph

• Dr. Russell Fraser, University of Prince Edward Island

• Dr. Michael Surette, McMaster University