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Mycotoxins — the invisible danger for livestock

Ruminant nutritionist offers tips to ensure feed doesn’t pose a health hazard to your cattle

Reading Time: 3 minutes

Mould and mycotoxins can be tricky, but there are a few tips that can help prevent them from hurting your cattle.

That was the message that Amanda Van De Kerckhove, ruminant nutritionist with Co-op Feeds, brought to Northlands’ first BeefTech event.

“It can be a little overwhelming when you look at all the factors that go into putting up quality feed,” said Van De Kerckhove. “A lot of it has to do with weather at the time of harvest.”

When it comes to grasses, it’s best to knock them down as soon as possible. The lignification process at maturation happens so fast that feed quality will go down rapidly. Rain will not only leach nutrients out of grasses lying in swath, but give moulds the opportunity to grow.

It’s also a good idea to consider what was in the field before because inoculum could be present from the previous year. Ergot and sclerotinia can also infect feed if weather conditions are correct.

It’s also important to cover your feed and stack it appropriately. The worst way to stack bales is in a mushroom-shaped stack, said Van De Kerckhove. Instead, put them in long lines in the direction of the prevailing wind.

“If you are putting up silage, get that harvest right,” she added. “The moisture content from the plant will target the right maturity level in that plant.”

It all comes down to packing and getting oxygen out of that silage.

“If there is oxygen left in there, there’s opportunity for mould,” she said.

An open flap on silage can allow oxygen to come in and contaminate the feed. Mouldy feed can also cause intake and palatability concerns. There’s also the risk of air contamination, when spores and fungus growing on mould are released into the air.

“If you are feeding, you can bust it up in a hay buster or shred it and you can get that blown off,” she said. “Just know that when you’re releasing those spores, you can have the potential to cause respiratory issues in the animal.”

Along with reducing feed quality, fungus or mould “also impairs the digestibility up to 15 per cent in terms of reduced production and reduced digestibility of that feed.”

The best solution is simply to not give mouldy feed to animals.

Invisible threat

Moulds can also produce mycotoxins, which are the secondary toxic metabolites of a stressed mould.

“Mycotoxins are really a mixed bag. They’re invisible, colourless and odourless. You do need a chemical analysis for mycotoxins,” she said. “If animals are refusing feed, take note of that. It’s not something to take lightly.”

Mycotoxin tests cost about $150 a pop and you need to submit a representative sample. There are multiple fungal classes that impact the crop and lead to mycotoxins. Fusarium produces Type A and Type B tricothecenes, also known as deoxynivalenol (DON), which causes cattle to go off feed and cause diarrhea or digestive problems. Fusarium mycotoxins can cause a secondary infection, such as pneumonia, and can also affect sperm motility. A less common mycotoxin, an estrogen-like compound called zearalenone, doesn’t have an effect on feeder cattle but can cause reproductive issues in cows.

“By far, zearalenone is pretty low on my list of concerns,” said Van De Kerckhove.

The big mycotoxins are T2 and HT2, which are commonly — but not always found — with DON.

Another concern is ergot, which appears at the honeying stage of flowering. Cool, cloudy weather at that time precipitates an elongation of that flowering. The honey dew can often infect more plants in the field, and change wheat and barley kernels into an ergot sclerotia.

Ergot can affect all cereal grains and forages, as well as any cool-season grass. The ergot body develops in the seed head, and in some cases, gets knocked off in the harvesting process. In this case, it can affect the plant the next year.

“Everybody likes to think about the barley and the wheat — those are easy because you can see those when they come through the mill,” she said. “It will be those hays and grasses that you’re not suspecting to be a problem, and any cereal byproduct. Keep in mind that your forages can be contaminated.”

Cereal screenings are high risk, as are distillers grains.

The good thing is that fusarium mycotoxin effects are reversible — “get some clean feed in front of them, and it will be gone,” she said.

Ergot can cause vasoconstriction, which results in less blood to the extremities and can cause ears, tails and feet to fall off. Animals may stamp their feet in order to try and get blood flow to their feet. Ergot can also cause reduced milk production if the cow eats infected feed when she is pregnant.

About the author

Reporter

Alexis Kienlen

Alexis Kienlen lives in Edmonton and has been writing for Alberta Farmer since 2008. Originally from Saskatoon, Alexis is also the author of two collections of poetry, a biography, and a novel called "Mad Cow."

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