Farmers in Drought-Stressed Areas Should Test for Aflatoxin

Aflatoxins have been found in some corn in northwest Iowa, so field specialists are urging farmers in drought-stressed areas to test their cornfields and feed for its presence.

Aflatoxins are a group of chemicals produced by certain mold fungi and can be fatal to livestock. They also are considered carcinogenic to animals and humans.

“We have had a few positive tests for aflatoxin – not a lot yet, and hopefully it stays that way – but we have had a few test for aflatoxin,” said Joel DeJong, an Iowa State University Extension field agronomist.

DeJong said the production of aflatoxins is related to drought stress. Warm, dry periods are breeding grounds for the toxins. He hoped the rainfall in August would reduce that risk, but there have still been a few positive reports of the toxins.

DeJong has heard of three reports from farmers who have confirmed aflatoxin in their fields, he said. The fields were in two counties in northwest Iowa – areas that saw very little rainfall through much of May through July. Also, the toxins were not widespread across those fields, he said.

However, corn growers must test for the toxin before harvesting their crop, or it won’t be covered through crop insurance.

“Crop insurance does not cover loss if it’s not identified in the field,” DeJong said. “So if you have all your corn harvested and haul it to the elevator and it tests positive for aflatoxin, your insurance will not cover losses identified at that time.”

Also, DeJong said improper storage of corn increase the level of toxin present.

Those with cattle should test their feeds for aflatoxin before giving them to their livestock, said Beth Doran, a beef field specialist with ISU Extension, who works with the Iowa Beef Center.

She said aflitoxins can reduce feed efficiency in cattle and reduce the reproductive capability in breeding cattle. And, while a less likely scenario, she said they may result in an animal’s death.

Livestock operators need to know if and how much aflatoxins are present in their feed and how to address them.

“It’s cheaper to send it in and get a test on it than it is to lose an animal,” Doran said.

The Food and Drug Administration has guidelines on what is an acceptable aflatoxin level in corn based on its intended use. Anything under 20 parts per billion (ppb) likely will return a negative test, DeJong said.

Corn intended for breeding beef cattle must have less than 100 ppb; for finishing cattle, less than 300 ppb; for young animals, less than 20 ppb; and for dairy cattle, less than 20 ppb.

The Iowa Beef Center at Iowa State University was formed in 1996 by a legislative mandate. Its goal is to support the growth and vitality of the beef cattle industry in the state. As part of ISU Extension, the Beef Center also serves as a central access point for all ISU programs and research related to the beef industry.