A plant disease caused by the fungus Claviceps purpurea, ergot, is nothing new, nor is its affect on animals who consume it. In fact, humans who ingested the fungus in the middle ages were said to have a problem known as “St. Anthony’s fire,” whereby narrowing of blood vessels would occur, and would often lead to changes in mental behaviour, as well as weakness, nausea, vomiting, gangrene and worse.
Symptoms of Ergotism in Cattle
“The first symptom of ergot poisoning is the animals will refuse to eat the grain or eat the forage that has the ergot bodies in it,” says Barry Yaremcio, beef/forage specialist with the Alberta Ag-Info Centre.
“If the levels are high enough, and they’ve got no other choice, they will eat a certain amount of the contaminated feed and the sloughing of hooves, reproductive problems, lack of milk in lactating cows — those things will all show up. But typically those animals will lose condition and lose weight… So it manifests itself in many different ways.”
Symptoms of ergotism will generally begin showing up in livestock 2-6 weeks after ingestion of ergot-contaminated feed. Because of the vasoconstrictive properties of alkaloids present in ergot, sloughing of hooves, ears and tails is common in affected cattle, along with changes in temperament and abortions in pregnant animals. And in cold conditions, animals are predisposed to frostbite and gangrene, potentially exacerbating ergot poisoning.
“I’ve noticed that if it’s fed during the wintertime — when it’s very cold, say, during a cold snap — because that toxin creates vasal constriction, then the blood supply to the limbs is reduced,” says Dr. Eugene Janzen, professor and assistant dean of clinical studies at the University of Calgary’s Faculty of Veterinary Medicine. “And if [the blood supply] is reduced, then that distal limb isn’t able to maintain itself in a warm condition and it’s more at risk to frostbite.”
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How do animals get it?
Quite simply, animals will show symptoms upon ingestion of ergot, which grows in cereals and grasses (most commonly occurring in those that are open-pollinated). Rye is especially susceptible to infection, with wheat and barley less susceptible and oats even less-so. Native and tame grasses may also be infected.
It doesn’t take much for an animal to receive poisonous doses of ergot.
“I’ve had producers count out 1000 kernels of barley and if there’s anywhere between 1 and 3 kernels of ergot in it, it’s too much,” said Janzen, who explained that Dr. Barry Blakely (a toxicologist at the Western College of Veterinary Medicine) says anything between 0.1 and 0.3% contamination can cause symptoms of ergot poisoning.
Whether eating pellets, hay, grain or greenfeed, animals may receive toxic doses. It is thus incredibly important to monitor feedstuffs for ergot, where possible.
“It’s very interesting; some of our feed companies that put supplements together, they use opportunity feeds like screenings and so on,” said Janzen, who explained that ergot seems to concentrate in screenings. “Some of our feed companies actually distributed supplements that were essentially toxic. And we’ve had outbreaks of ergotism in those kind of places.”
Is incidence increasing?
In the past few years, we have been hearing of more reports of ergot poisoning, and higher levels of ergot in cereals. Part of the problem, according to Yaremcio is that we’ve had some really wet years, high humidity and cloudy, cooler conditions during flowering. These factors contribute to a longer flowering period and thus a greater opportunity of spore contamination.
“To give you an idea of how bad some of the problems are: we’ve had screenings tested from this area with 33000 parts per billion alkaloid,” says Yaremcio. “So they’d have to put 1kg of the contaminated grain in 170kg of some other feed to make it safe to feed.”
Janzen, who says he heard little of ergotism until a few years ago, suggests no-till management may beneficial for the spread of ergot.
Preventing Ergotism in Livestock
“Typically, ergot poisoning symptoms start to occur 4-6 weeks after you start feeding ergot-contaminated grain,” says Yaremcio. Don’t wait, then react to something happening “because some of these animals will never recover; prevention is the best cure in this situation.”
Prevention starts right from planting. Ensure adequate crop rotation to unsusceptible species and watch fertility. Cultivation may also be a cultural control strategy, suggests Yaremcio as ergot bodies covered with over 3/4″ of soil won’t germinate/produce spores.
“The grading standards have become a lot tighter this year than in the past,” says Yaremcio.
And sure, these changes have potential in helping nation-wide management, but don’t let your guard down. If you’re buying or keeping feed, check it before it’s in the ration. If ergot bodies are present, either dilute concentration to levels deemed safe, or dispose of the feed entirely.
For animals you suspect have ergot poisoning, there’s not much you can do. Treat and manage the symptoms, and get the animals off the ergot-contaminated feed. If you decide to send them to slaughter early, allow sufficient time for withdrawal of ergot-contaminated feed, and only transport animals if both safe and humane to do so.