A pan-Canadian team of researchers is evaluating potential alternatives to antibiotics and zinc oxide for protecting piglets from diarrhea during weaning.
The University of Guelph and the University of Manitoba are leading the research, which the Swine Innovation Porc funds through Swine Cluster 4. The research explores the roles of swine genetics and the gut microbiome in fighting postweaning diarrhea.
Swine Innovation Porc (SIP) announced earlier in 2024 an investment of over $10.6 million by the Government of Canada in Swine Cluster 4, a strategic research program driving innovation in the Canadian pork sector until 2028. This initiative is made possible with support from Agriculture and Agri-food Canada’s Sustainable Canadian Agricultural Partnership – AgriScience Program, in collaboration with leading industry partners.
Dr. Vahab Farzan, a research scientist and adjunct Professor in the Department of Population Medicine and Pathobiology at the Ontario Veterinary College with the University of Guelph, said this project focuses on postweaning diarrhea associated with pathogenic E. coli.
The goal is to investigate the prevalence and frequency of diseases on swine farms across Canada to discover what diseases are caused by different types of E. coli.
First off, researchers want to know what types of E. coli cause diseases on swine farms in Canada.
Secondly, some pigs are genetically resistant to getting infected by this bacteria. Still, they need to know what proportion of the pigs in Canada are resistant and what proportion are susceptible.
“We would like to understand the frequency or prevalence of genetic susceptibility in Canadian pigs,” said Farzan.
Finally, the third goal of this study is to examine the gut microbiome because, based on science, there is a solid relationship between the gut microbiome and gut health. Postweaning E. coli diarrhea is a gut health issue, so if the pig has a very healthy bacterial population in the gut, she will be more likely to fight against E. coli infection.

“Our objective is to look at the gut bacterial population, which we call gut microbiome, and then compare the pigs that have postweaning diarrhea with those that don’t.”
Postweaning diarrhea (PWD) in pigs is a common issue caused by various microbial agents, including E. coli. This condition, often marked by watery diarrhea, leads to dehydration and poor growth performance. High levels of zinc oxide and antimicrobials in feed are commonly used to prevent PWD but contribute to environmental concerns and antimicrobial resistance (AMR). AMR genes can spread from E. coli to other bacteria and even pose public health risks as resistant genes can enter the food chain, potentially causing treatment failures in human medicine.
The swine industry is increasingly moving towards banning zinc oxide in pig diets and reducing antimicrobial use due to the environmental and health risks associated with these practices. Postweaning diarrhea (PWD) continues to present significant economic challenges, costing the Canadian swine industry an estimated $100 to $150 million annually.
“This cost includes mortality, production losses, and expenses for treatment and vaccinations,” he said.
Efforts to address PWD involve improving bio-security and reducing reliance on harmful treatments to prevent further issues like antimicrobial resistance and environmental contamination.
Dr. Farzan said the infection in pigs caused by E. coli spreads through bacteria equipped with structures called fimbria, which attach to receptors in the pig’s intestine. There are five types of fimbria, but F18 and F4 are the most common. This attachment allows the bacteria to release toxins that cause diarrhea and dehydration. Some pigs are genetically resistant as they lack the receptors.
“Postweaning diarrhea is common on swine farms, influenced by genetics, farm management, and other factors like the use of antimicrobials or zinc oxide.”
Anyone interested in learning more about this pan-Canadian project can email the lead researcher for detailed information. The project involves collaboration with several universities across Canada, including the University of Manitoba, McMaster University, and the Ontario Veterinary College. Suppose swine producers are experiencing ongoing issues with post-weaning diarrhea. In that case, they can contact the research team to collect samples from their farms and work alongside their veterinarians to analyze the results and share the findings.
Dr. Farzan said the project is in its early stages, and he is looking forward to sharing results as they become available. •
— By Harry Siemens