Because of this fall’s record rainfall and cold weather, Illinois dairy producers should beware of mold and mycotoxins in corn, according to Mike Hutjens, University of Illinois extension dairy specialist.

University of Wisconsin experts are asking their producers to watch for the same problems.

Besides reducing bushel weight, corn quality and nutrient content, moldy corn increases the chance of mycotoxins that can cause rumen disorders. Signs of toxin problems include loose fecal discharges; reduced microbial digestion, dry matter intake and fertility; hormonal changes; and immune suppression to disease challenges, Hutjens says.

“Dilution of contaminated feed with clean feed can reduce mycotoxins to acceptable levels, but be forewarned – contaminated feed can vary greatly in concentration,” he says.

If you’re concerned that mold could cause problems, the feed can be tested. But those tests can be expensive and sampling and feed variation can reduce the usefulness of the results, Hutjens says.

Adding a mycotoxin binder may help. “Binders include yeast cell wall extracts or MOS products and clay binders.”

Mold growth could increase in high-moisture corn until the pH drops, but drying corn below 15% moisture stops further toxin development. “Adding a grain inoculant to speed up fermentation and stabilize the wet corn is recommended. And steers can tolerate higher levels of problematic feed than young animals and pregnant cattle,” Hutjens points out.

Removing fines, damaged seeds and cracked corn kernels can reduce toxin risk. If you buy corn screenings, expect higher mycotoxin levels. Production of distillers grains can concentrate the level of toxins in the feed, he suggests. Adding propionic acid at ensiling can reduce mold development in wet corn.

Across Wisconsin, the primary ear molds causing mycotoxin contamination in high-moisture or dry shelled corn include Diplodia, Fusarium, Gibberella and Penicillium, state specialists note. Conditions have been less favorable for the development of Aspergillus.

The longer corn stays in fields, the higher the risk for mycotoxin development, the experts say. They recommend that producers monitor grain throughout the winter; when corn was infected in the field, contamination can occur much later.