OVC Student Veterinarians Share Externship Experience: Apparently all hay is not created equally

Each summer DVM students from the Ontario Veterinary College delve into practical experience at veterinary clinics across Ontario and additional locales. These blog posts are an opportunity to tag along with five of them this summer. This week student veterinarian Jodi took a pasture-to-plate approach to some hay samples. Check out all the student blogs at www.ovc.uoguelph.ca/externship

Working with Dr. Bob brings the unique opportunity to focus on some of his specialties like horse nutrition and toxic plants. Each week, we make our way into the fields to discover what is growing and where. I have already learnt a ton about the plants covering Southern Ontario pastures in early summer and have a better idea about the amount still left to learn.

This week, we also had the unique opportunity to take a ‘pasture-to-plate’ approach to our regular pasture walk. I got to consult with Dr. Bob on a hay sample analysis submitted by a curious client. The client wanted Dr. Bob’s comments on the hay composition as well as insight specifically on if the hay contained a toxic plant called hairy vetch (Vicia villosa).

Hairy vetch (Vicia villosa) was originally introduced from Europe and derives its name from its hairy stems and leaves. It is toxic to both horses and cows if it is consumed in large quantities (as a major portion of their diet) when the plant is reaching maturity. Typically, hairy vetch poisoning results in an immune system response that leads to skin issues, weight loss, diarrhea, and inflammation throughout the body. In large enough quantities, pregnant animals may abort their fetuses and mature animals may die suddenly. It is no wonder the client wanted to make sure we looked specifically for hairy vetch in the hay samples – it can be quite a nasty plant!

We set up our analysis station in front of the clinic and combed through the samples that were submitted. A passerby even commented that we “look like kids playing in a sandbox” – it was quite fun!

Above is a photograph of some of our plant findings within the hay samples. Each plant species contributes a different nutrient profile to the overall hay affecting its quality and suitability for different life stages like foals, adult horses, or pregnant mares. From left to right in the photograph: red clover (with flowers), tufted common vetch (upper), tufted common vetch seed pods (lower), tufted common vetch freshly-picked, alfalfa (with flowers), mature orchard grass, mature brome grass, timothy hay, and mature blue grass. Luckily, we did not find any hairy vetch in our searches and tufted common vetch does not have the same toxicity issues!

I had no idea how much complexity went into a bale of hay until I spent an afternoon ripping some apart and looking at them stem by stem. I realize now that I had little respect for the plethora of species that exist and make up what I previously referred to as “grass”. After a bit of time with the specialist though I have learnt that all hay is not created equally!

Comments are closed for this blog post

Welcome to
Ontario Agriculture

Sign Up
or Sign In

Agriculture Headlines from Farms.com Canada East News - click on title for full story

Ag in the House: Dec. 1 – 5

A Liberal minister reminded the House the carbon tax doesn’t apply to farmer

Ontario Animal Health Network (OAHN) Swine Network Quarterly Industry Report

Starting in 2015, Senecavirus A (SVA) has caused intermittent complications with respect to the export of Canadian cull animals to the United States. This disease resembles reportable swine vesicular diseases. This is a national issue and since June 2025 has impacted Ontario cull sow movements. In July 2025, the APHIS and the USDA removed the export eligibility status for a cull sow assembly in Ontario due to SVA lesions being seen in cull sows sent to a USDA processing facility. These lesions initiated foreign animal disease investigations at this US processing plant. The suspect animal(s) were initially quarantined for individual inspection and further testing. Since the initial site, another 2 Ontario cull sow assembly sites have also had their export eligibility status revoked by APHIS and the USDA for similar reasons. The affected assembly sites accept cull sows from Quebec, the Maritimes and Ontario. Each affected assembly site must action the USDA requirements including emptyin

New restrictions placed on hunting, farming 'incredibly destructive' wild boars in Alberta

Wild boars have been declared "a pest in all circumstances" by the Alberta government effective Dec. 1, meaning new restrictions have been placed on keeping them in captivity and hunting them in the wild. It is now illegal to keep, buy, sell, obtain or transport wild boars in Alberta without a permit. That also means no new wild boar farms will be permitted in the province. The hunting and trapping of wild boars in Alberta is banned as well, with the exception of land owners or occupants killing the animals on their own land. Any person who kills a wild boar is now required to report the date, location and number of boars killed to the province as soon as possible. Hannah McKenzie, the province's wild boar specialist, says the changes were made due to the dangers posed by existing wild boar populations and the risks associated with more escaping from captivity. "In addition to damaging agriculture and the environment, wild boar pose a serious risk for the introduction and spread of

CUSMA Review Raises Concerns Over Potential U.S. Tariffs on Canadian Pork

As the first formal review of the Canada-United States-Mexico Agreement (CUSMA) approaches in July, pork producers across North America are bracing for potential impacts—especially the possibility of new U.S. tariffs on Canadian agriculture. Florian Possberg, Partner at Polar Pork Farms, says the U.S. political landscape is shaping expectations. He notes that U.S. President Donald Trump has repeatedly pushed for a baseline 15% tariff on foreign goods in recent global trade discussions. If that approach carries into the CUSMA renegotiation, it could disrupt one of the pork sector’s most critical trade corridors. Free Trade Has Been Essential for Pork Movement Possberg emphasizes that under CUSMA, both live hogs and processed pork products have flowed freely across borders without tariffs. This freedom is especially important given the highly integrated nature of North America’s pork supply chain. The best-case scenario, he adds, is that tariff-free access continues unchanged. The wor

FCC report highlights productivity as key to Canada’s agricultural future

Canadian farmers could see significant income gains and new opportunities if agricultural productivity growth returns to historic highs. The Farm Credit Canada (FCC) report titled Reigniting agricultural productivity in Canada, estimates that boosting productivity growth to two per cent annually could unlock $30 billion in additional farm income, generate $31 billion in GDP, and create nearly 23,000 jobs across the country. Canada has long been a standout among global food producers. Over the past half-century, the agriculture industry has achieved significant productivity growth through better farm management, improved input efficiency and technological innovation. The report warns, however, that productivity growth has slowed in recent years, threatening the industry’s competitiveness and Canada’s ability to meet growing national and global food demand. “Canada’s agricultural productivity growth has consistently outpaced other G7 countries for more than three decades, showing the s

More…

Badges | Report an Issue | Terms of Service