It is a moving target that changes. Not only does the presence of mycotoxins change year by year due to field conditions, plant stress, moisture or drought, the conditions within a bunker or forage bag can be different in different locations.

Packing success and consistency, product consistency throughout the pack, tightness of seal and elimination of oxygen all impact the degree to which mycotoxins will affect the dairy herd.

Let’s face it: These troublemakers that originate in the field are found everywhere. No two farms and no two fields within one farm are alike. The mycotoxin load that sends one herd into a tailspin might barely be noticed in another herd.

Why one herd and not the other? That depends. There are more than 700 mycotoxins, according to Dan Armstrong, owner of Advanced Preservative Systems. Only 12 of those have names. “Just because a forage sample comes back clean, that doesn’t mean mycotoxins aren’t there; they just aren’t detected and identified,” Armstrong says.

“Mycotoxins are always a problem, but when we test more regularly, we find them more regularly, and we may falsely believe they are a larger problem than they really are,” says Nathan Meeuwse, dairy nutritionist with Cornerstone Ag Management LLC in Wayland, Michigan.

While some people use mycotoxin management products year-round, others use them as needed, depending upon what is observed within the herd. Sometimes a problem rectifies itself simply because by the time a situation is identified and pinpointed, that spot in the bunker or bag has probably been fed and eliminated.

Both approaches are neither wrong nor right. The second approach may cost less up-front. It could also result in hefty veterinary bills, reduced production or drop in butterfat. The key is having a good handle on the farm’s overall risk factors.

Cause and effect

Milk and butterfat production; fiber digestion capacity; reduced rumen protozoa; foot, skin and udder health; general cow health and the ability to fight off secondary infections are just some of the tell-tale signs of larger-than-normal forage mycotoxins.

Still, the same levels and combinations of mycotoxins may be found on two different farms yet yield entirely different results. Gut health, immune system and environment are all factors that determine how a cow will handle the disruption.

Mycotoxins may not be the direct cause of a problem, but rather it is their impact on the rumen microorganisms that causes the cows’ disruption. Dr. Max Hawkins, nutritionist working with Alltech’s mycotoxin management teams, says this is where binding products can have a big impact by allowing those toxins to pass through the rumen without interacting with existing gut organisms.

Even if a cow is a low risk through good health and immunity, she cannot forget that she consumed mycotoxins and the risks are cumulative over time.

DON/vomitoxin is a field-sourced mycotoxin. Penicillium, a storage mold, can magnify quickly with only small amounts of oxygen. Combined, the two have a synergistic impact on the rumen.

Mycotoxins are beginning to be the first thing investigated in poor performance or health situations. “We are beginning to understand which mycotoxins impact which production trait,” Hawkins says. More study is needed to determine the impact of different specie combinations. Also, the severity of a production impairment may be magnified by the mold species that incubated the mycotoxin.

Harvest years compared

Hawkins is a little surprised at the forage test results being generated from last year’s crops. From excessively wet fields, drought-stressed and overly mature plants, 2019 saw it all.

“We are seeing an average of 8.5 mycotoxins per sample,” Hawkins says. The range is from three to 15, but five to eight different toxins per sample is the average for Alltech labs.

“We have a moderate to high risk for health issues around mycotoxins, but it hasn’t gotten as bad as we thought it would. We don’t really have a good explanation,” Hawkins says. “A lot of forage got exposed to a lot of wet weather, got harvested past maturity and didn’t ensile well. We still see some samples that are very risky – but not as often as we thought we might.”

Jeremy Runyan, business development director for Alliance Analytical, says DON levels in corn silage tested through their Coopersville, Michigan, laboratory were essentially the same at 2.43 parts per million (ppm) for the first half of 2020 versus 3.5 ppm DON during the first half of 2019. However, there were only 12 tests done thus far in 2020 compared to over 600 tests during the same timeframe last year.

“A lot of corn silage was already frozen going into the pile,” Runyan says. “Because it wasn’t fermenting as well, the mold has potential to grow at a higher rate. The high dry matter creates a different set of problems and may have allowed for more air entrapment in the bunker.”

Mycotoxin management tools

Experts agree that the first tool in managing mycotoxins is routine testing and more frequent testing when there is a wet harvest.

Binders disable contaminants by trapping them in a clay or other porous material through adsorption. DON, which is structure flat, becomes trapped between layers of binding material, much like a burger in a bun. A good binder will box off the flat-shaped aflatoxins and most endotoxins. Mycotoxins which are more rounded require different binding materials.

According to Hawkins, mycotoxin management tools can be effective or not, depending on the type of toxin, binder and amount used. Straight clay types are inexpensive, used in large quantities, but are only good against a handful of mycotoxins and not effective against DON. Multiple-ingredient binders yield more complete results. Enzymatic action products are complex and work best in ideal environments but, in the real world, ideal environments are rare. He says various research both supports and detracts from adding binders to forages.

Along with good packing and sealing to the bunk or bag, a good preservative helps reduce molds that give mycotoxins a conducive growing environment.

“You can’t stop mycotoxins, but you can slow them down by reducing the presence of yeast and molds through forage treatment, especially in years where there is a lot of crop stress,” Armstrong says.

“Everybody needs to understand what risk they have on their farm, and in order to do that, you have to test,” Hawkins says. “At the end of the conversation, this is the question: ‘How much is this mycotoxin costing me? And if I use a product, how much will it make me?”