Breeding parasite-resistant sheep

Research by Dr. Emma Borkowski aims to give producers new tools

By Lilian Schaer for Livestock Research Innovation Corporation

Parasite control has long been one of the toughest challenges for sheep and goat farmers. Gastro-intestinal worms reduce weight gain and wool quality, cause scouring and anaemia, and in severe cases can kill animals. 

For decades, deworming drugs were the go-to solution — but as resistance continues to grow, scientists and farmers alike are looking for new tools to protect animal health.

One of the researchers working on this problem in Canada is Dr. Emma Borkowski, a veterinarian and assistant professor at the University of Guelph. Her work focuses on understanding the immune responses that sheep and goats produce against these parasites — and how those responses could eventually help farmers breed animals that are naturally more resilient.

Borkowski is a winner of an Early Career Research Mentorship Award through the Livestock Research Innovation Corporation (LRIC). The program helps young scientists connect with mentors and industry partners across livestock sectors. 

“The mentorship has been incredibly valuable,” she says. “It’s given me exposure to people working in other areas — swine, dairy, beef — and that helps me think differently about how to communicate and apply my research. It also means when I reach out to someone new, they might already have heard about my work.”

Her current projects are supported through Ontario Sheep Farmers (OSF), the Ontario Ministry of Agriculture, Food and Agribusiness (OMAFA), the Ontario Agri-Food Research Initiative (OAFRI), and AgResearch New Zealand, among others — illustrating the strong network behind this growing body of work.

From New Zealand inspiration to Canadian adaptation

Borkowski’s research builds on a New Zealand discovery that changed the way sheep producers there think about parasite control. Researchers in that country developed a simple saliva-based test that measures antibodies produced in response to intestinal worm infections. 

High antibody levels in saliva mean the animal’s immune system is actively fighting off parasites — and those immune traits can be inherited, allowing farmers to select breeding stock with naturally stronger immunity.

“New Zealand is years ahead of us because of the size of their industry and their outdoor, year-round grazing systems,” Borkowski explains. “The same parasites exist here, but our climate and management are completely different. We have a long winter with snow cover when there’s no pasture exposure, so we didn’t know if our sheep could mount a similar immune response.”

During her PhD, she and her colleagues — including Drs. Andrew Peregrine, Niel Karrow, and Paula Menzies — were the first team to test this system outside New Zealand in Canadian sheep. Early results were encouraging: Ontario animals could indeed generate protective antibody responses.

That success led to an international collaboration between AgResearch New Zealand and the Animal Health Laboratory (AHL) at the University of Guelph. Once the necessary validation work is complete, AHL will become the first diagnostic lab outside New Zealand to offer the saliva-based antibody test to Canadian producers. Samples will be able to ship overnight on ice instead of being couriered halfway around the world.

Filling in the missing pieces

Before the test can be adopted widely here, researchers need to understand how Canadian management conditions — housing systems, lambing schedules, and pasture timing — affect immune responses.

This summer, Borkowski’s team began controlled trials at the University of Guelph’s Ponsonby research station. Using worm-free sheep that are given carefully measured exposures to worms, the group is monitoring antibody levels weekly to see how quickly responses develop, how long they last through winter, and how factors such as age or sex influence immunity.

“These trials will tell us how to interpret the saliva test under Canadian conditions,” she says. “If we know when antibody levels peak or fade, we can recommend the best time for producers to sample their animals.”

Over the next three years, her group will also investigate how nutrition influences immunity — for example, whether compounds such as condensed tannins in feed can “dial up” antibody production. 

They’ll also explore how different parasite species trigger immune responses and whether genetic selection programs like GenOvis might eventually include parasite-resistance traits.

Beyond sheep: goats and the search for better vaccines

Sheep aren’t the only focus. Borkowski is also studying parasites in goats through a major project funded by the Organic Science Cluster 4 in partnership with OMAFA, Ontario Goat, and the Canadian National Goat Federation.

“Canadian goats face the same parasites as sheep, but we don’t yet know if they produce the same types of antibodies or how long those antibodies last,” she says. “We’re collecting data now to see whether the same saliva test can be used for goats too.”

Another new direction looks even deeper — at the immune cells themselves. Using tools originally developed for human and mouse research, her lab is hunting for a special type of immune cell, called an iNKT cell, that can recognize certain parasite molecules and trigger antibody production in the gut. 

Finding those cells in sheep or goats could be a major step toward creating a truly effective vaccine for internal parasites — something that doesn’t currently exist in Canada.

“The only commercial vaccine available elsewhere is made from ground-up parasites and has to be given repeatedly,” she explains. “If we can figure out how to stimulate the right immune cells directly, we could design something more practical for farmers.”

Building a sustainable future for parasite control

For Borkowski, all of this work fits together as part of a larger research program focused on sustainable parasite management.
“We’ll always need dewormers, but they should be our last resort,” she says. “If we can breed and manage animals that are naturally more immune, we’ll use fewer drugs, slow resistance development, and make life easier for both producers and animals.”

From mentoring to molecular biology, Borkowski’s early-career journey shows how collaboration across sectors — and across species — can accelerate innovation. Ontario’s sheep and goat farmers will be watching closely as her findings start to make their way from the lab to the barnyard.

This article was written by LRIC for Sheep News in 2025.