Mycotoxin risk elevated due to wet growing season

As wet weather continues to delay fall harvest on Ontario farms, livestock producers and their nutrition advisors are watching for signs of elevated mycotoxins in their feed.

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Results from the 2023 Corn Ear Mould survey from the Ontario Ministry of Agriculture, Food and Rural Affairs confirm there’s cause for concern.

Why it matters: Elevated mycotoxins in feed can negatively affect production, health and reproduction in multiple livestock species.

“Growers should be vigilant, as they may have fields with elevated DON (deoxynivalenol, also referred to as vomitoxin),” OMAFRA said in an Oct. 25 Field Crop News article about the survey. “Fields should be evaluated for risk and consider harvesting and drying higher risk fields before infections worsen.”

The survey highlights only the field-formed mycotoxin risk. As wet conditions persist and farmers harvest in less-than-ideal conditions, the risk also rises of mycotoxin-forming organisms thriving in feeds after they’ve been stored.

For the survey, 192 samples were collected between Oct. 2-5 from across the province.

“DON concentrations were higher than long-term survey averages,” reported the Field Crop News article.

DON is present at some level every year in Ontario corn crops. Ideally, virtually all of those fields have concentrations less than two parts per million. Realistically, the 10-year average from the OMAFRA surveys — conducted in cooperation with Grain Farmers of Ontario and the Ontario Agri-Business Association — sits at 88 per cent of samples testing below that threshold.

In early October, 77 per cent of the samples tested below two ppm for DON. Samples with greater than five ppm only occurred from London west, but there were samples collected between two to five ppm in all corn-growing regions.

Paul Garvey, Hanover-based Canadian sales manager for feed additive manufacturer CBS Bio Platforms, says those numbers are cause for vigilance.

“The flags are up that protecting feed quality will be important this year post-harvest,” said Garvey, a poultry nutrition specialist, in a recent news release from the Calgary-based company. “We’re advising farmers and feed mills to plan ahead and have mitigation options ready.

“Corn yields look very good (in Ontario),” Garvey added when contacted by Farmtario. “But there were challenges with spraying fungicides due to weather conditions and a lot of excess moisture, creating the possibility of toxin challenges.”

The Field Crop News article outlined factors that support the growth of mycotoxins, and wet weather topped the list. After a dry planting season extending through a few weeks of germination and growth, the weather became less stable and rainfall events began, continuing through August and into early September for many areas. In addition to moisture, there were few prolonged hot spells.

“With lower-than-normal heat unit accumulation in 2023, the corn crop is less mature and higher moisture than normal in many cases,” the OMAFRA article states. “This can be a risk for continued ear mould activity until grain moistures or temperatures drop enough to limit activity.”

Weather conditions also resulted in above normal feeding by pests, according to the DON survey, which opens husks and damages kernels. That provides opportunities for ear mould infection.

“While still only representing a minority of samples, feeding damage appeared more common than what has been observed in recent surveys,” the OMAFRA article said.

Garvey said the survey results only tell part of the story. With much of the province’s corn still in the field at the end of October, conditions were favourable for further mycotoxin development. Storage could present its own risks.

“Work with your (feed) supplier,” he advised, “and make sure they have a program in place to deal with potential contamination and/or help you with toxins on your farm. Make sure you are managing your grain storage to optimize results.”

Pigs, especially lactating sows and young piglets, are the most susceptible among all common livestock to mycotoxin contamination. In the October edition of Ontario Pork’s News and Views, OMAFRA swine specialist Laura Eastwood offered tips on dealing with feed sources that test high in mould.

“In most years, blending of multiple ingredients into a final diet will sufficiently dilute the mycotoxins in the feed; however, in years with higher than normal mycotoxin presence, there may be a need to blend contaminated and clean grain of the same kind to create a ‘stock grain’ with lower total concentrations to use in diets,” she wrote.

She offered a particular caution to producers who use distiller’s byproducts.

“Mycotoxins that were present in parent grains will be concentrated up to three times in distiller’s grain products, and thus extra care is needed when including them.”

CBS Bio Platforms is among the companies offering feed additives to mitigate the risks of mycotoxin contamination. Additives can include probiotics or enzymes that consume or facilitate the consumption of toxins, products that act on mycotoxins physically (such as clays that bind to the toxins) or chemically (such as ammonia or formaldehyde).

Eastwood urges caution when using chemical products, as they could affect palatability or run afoul of food safety regulations. She offers assessments of various feed additives at the ONswine website.