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Build resiliency against mycotoxins this fall

Neil Michael for Progressive Dairyman Published on 28 September 2018
Immune suppression is one way mycotoxins affect cow health and production

No dairy is immune to the negative effects of mycotoxins on animal health and performance. In tests of the 2017 U.S. corn crop across 23 states, 91 percent of grain, silage and corn byproduct samples contained mycotoxins.

These unseen enemies also lurk in oilseeds, byproduct feeds, protein concentrates, wet brewers grains, food wastes and forages.



Exposure to mycotoxins through rations can suppress cattle immunity, hamper reproduction and reduce nutrient utilization and feed intake. It’s often difficult to spot mycotoxin contamination because symptoms are so wide-ranging and often seem unrelated.

Considering the pervasive nature of mycotoxins, it’s essential for dairy producers to find ways to mitigate their economic impact.

What are mycotoxins?

Mycotoxins are metabolites produced by fungi commonly found in feedstuffs. They can form wherever molds exist – in the field, at harvest, during storage and processing, and even at feedout. Most fungi produce several mycotoxins simultaneously, and there are thousands of different species.

When feedstuffs contain multiple mycotoxins, their impact is not as simple as 1 + 1 = 2. Mycotoxins can have a cumulative effect, creating an even greater risk of dairy performance loss.

Growing conditions can affect the severity of mycotoxin contamination. Cool, wet weather favors Fusarium toxins, while heat and humidity encourage aflatoxins produced by Aspergillus. Therefore, Fusarium toxins are more common in the Northeast and Midwest, while aflatoxins occur frequently in the South and West.


If you are bringing in feedstuffs from other regions, it’s not safe to assume rations are mycotoxin-free just because certain mycotoxins are not prevalent in your area.

Every day, every bite

Feed analyses, while valuable, can miss some mycotoxin species. Rather than rely on testing, it’s best to assume mycotoxins are present in the feed and manage accordingly. Your goal should be to make your herd resilient against the pervasive risk of mycotoxins – every day and in every bite.

Researchers are learning more about the ties between gut health and overall immune function, especially related to mycotoxins. This is of key interest because immune suppression is one of the ways mycotoxins affect cow health and production.

The intestines are the first area of the animal to be exposed to mycotoxins – and often at higher concentrations than other tissues. Maintaining a healthy gastrointestinal lining is crucial, as it ensures nutrients are absorbed at an optimum rate and protects the body against pathogens through its own immune system.

Mycotoxins affect the animal at the point of attack (locally) and throughout the body (systemically) when inflammatory compounds reduce overall immune function. A ripple effect opens the door for opportunistic diseases that negatively impact reproductive performance and animal productivity. The worst-case scenario is animal mortality.

Scott Blevins, manager of Weise Brothers Dairy near Greenleaf, Wisconsin, saw the worst-case impacts of mycotoxin firsthand. When the 6,000-cow dairy experienced digestive issues and death losses, testing confirmed suspected mycotoxin presence. “It’s losing cows that alarms you,” Blevins says.


Proactively manage mycotoxins

Considering the potentially severe impact of mycotoxins, dairy producers should consider an approach similar to how they handle subclinical milk fever and ketosis: Assume mycotoxins are present and proactively manage the herd to reduce their negative effects.

For decades, the primary method of management was through mycotoxin binders, using materials like bentonite to inactivate some strains of mycotoxin after ingestion by the cow. But since binders aren’t effective on all mycotoxin strains, those strains often damaged the intestinal cells lining the gut, even with use of binders. A newer, more effective approach is to focus on protecting the gut from mycotoxin damage.

Refined functional carbohydrates (RFC) is a new technology that helps counteract mycotoxins and helps prevent them from being absorbed through the gut and into the blood circulation. This reduces the negative influence of mycotoxins that can decrease dairy performance.

In addition, immune suppression caused by mycotoxins can be reversed by beta 1,3/1,6 glucans and mannans present in RFCs, allowing further protection against the pathogens. Better nutrient uptake leads to improved feed efficiency, enhanced reproduction and increased animal performance.

Ultimately, the increased protection from RFCs enables animals to devote energy to all functions – especially reproduction – instead of staving off infections or struggling to maintain nutrient uptake. That means cows are better able to weather the ill effects of mycotoxins.

Adding RFCs to the lactating cow ration mitigated the mycotoxin crisis at Weise Brothers Dairy. “We investigated a number of binders, but none provided the full solution,” Blevins says. “We know mycotoxins are there and RFCs give us a layer of protection against them.” To that end, Blevins continues to feed RFCs routinely in calf and heifer rations.

Don’t overlook silage making

A complete management plan against mycotoxins must also include best practices to prevent mold formation in the first place. Follow these steps when harvesting corn silage this fall:

  • Harvest at the proper crop maturity and moisture level based on your silage hybrid.

  • Chop at an optimum length, keeping blades sharp for a consistent cut.

  • Achieve adequate packing to eliminate oxygen and facilitate fermentation.

  • Seal the bunker properly to keep oxygen out.

  • Apply inoculants to speed up the fermentation process and achieve the proper pH and stable anaerobic conditions.

  • Use good bunk face management techniques to preserve quality during feedout.

The odds are extremely high mycotoxins are present in your feedstuffs and threaten herd health, production and reproduction – reducing your economic return. Now is the time to take steps to boost the resiliency of your herd to fight back against mycotoxins.  end mark

PHOTO: Immune suppression is one way mycotoxins affect cow health and production. Getty Images.

Neil Michael received both DVM and MBA degrees from Purdue University and has over 30 years of industry experience including veterinary practice, dairy management, reproduction and nutritional consulting.

References omitted but are available upon request. Click here to email an editor.

Neil Michael
  • Neil Michael

  • Manager, Ruminant Technical Services
  • Arm & Hammer Animal Nutrition
  • Email Neil Michael