Frequently Asked Questions about Aflatoxin in Corn:
(September 14, 2012)
Q:What is aflatoxin?
A: Fungi in the genus Aspergillus produce aflatoxins. These Aspergillus fungi can colonize corn kernels causing an ear mold or ear rot. The most common Aspergillus species that affect corn are Aspergillusflavus and Aspergillusparasiticus. Aflatoxins are carcinogens (cancer-causing agents) in animals and humans.
Q:What does the Aspergillus ear rot look like?
A:Aspergillus ear rot appears as an olive-green colored mold growing on and between corn kernels on an ear.
Q:What conditions favor aflatoxin contamination of grain?
A:Drought and high temperatures during the corn grain fill stages are the most favorable for the development of aflatoxin in grain. Pictures of Aspergillus ear rot are available on-line at:
Q:What can I do to prevent Aspergillus ear rot and aflatoxin contamination of grain in my fields?
A:When conditions are very favorable for Aspergillus ear rot and contamination (hot temperatures and droughty conditions), prevention of the disease and the toxin development can be difficult. Any practices that minimize stress from heat and drought may limit development of Aspergillus ear rot and aflatoxin. Planting hybrids adapted to local soil types and conditions, maintaining good fertility and soil conditions may help alleviate heat and drought stress. Managing insects that feed on silks and ears also will reduce exposure of kernels to Aspergillus fungi. A product known as “Aflaguard” from Syngenta Crop Protection is registered for use on corn to help prevent high aflatoxin contamination levels. This product has not been tested by the University of Illinois, but has been tested by scientists at Texas A&M University. Some results from Texas A&M field studies have indicated that alfatoxin levels were reduced compared to non-treated controls. The Aflaguard product contains a strain of the Aspergillus fungus that does not produce aflatoxin. Aflaguard must be applied prior to tasselling and silking to achieve the best efficacy.
Q:Should fields that are at the highest risk for aflatoxin be harvested differently than other fields?
A:Fields that have suffered the most from drought and heat stress would be at a higher risk of having higher levels of aflatoxin contamination. These fields should be harvested first and immediately dried to below 15% moisture. Drying the corn to below 15% moisture will prevent additional mold development and aflatoxin production. For long-term storage, grain should be dried to below 13% moisture. Adjusting the combine settings to limit the number of broken kernels and amount of trash in the hopper may reduce aflatoxin levels in the harvested corn, as broken kernels tend to have the highest level of aflatoxin contamination.
Q:What crop insurance implications are there for aflatoxin contaminated grain?
A:Aflatoxin contamination is considered a quality-loss, and is covered by crop insurance. If aflatoxin is suspected, the crop insurance agent should be contacted immediately. An independent test for aflatoxin must be done before the field is harvested, so it is imperative that the crop insurance agent be contacted immediately if aflatoxin is suspected or detected. For more information about crop insurance implications of aflatoxin in corn, go to:
Q:I have aflatoxin contamination in my grain, is there anything I can do to lower the aflatoxin level?
A:Running the grain through a rotary screen to take out fines may reduce the level of aflatoxin contamination. Damaged and broken corn kernels tend to have the highest level of aflatoxin contamination. Cleaning out these broken and damaged kernels should reduce the level of aflatoxin. It is important that the screenings from the cleaning process not be used for animal feed; however, as the aflatoxin levels may be very high in this material.
The process of ammoniation has been shown to reduce aflatoxin contamination levels in corn. The ammoniation process detoxifies the grain. This process generally can be done only for on-farm livestock feeding use, as the FDA does not allow ammoniated corn to be shipped in interstate commerce. The ammoniation process may discolor corn and will leave a temporary off-odor on the corn, which could result in feed refusal by animals. Because the ammoniation process is somewhat dangerous, it should be conducted only by trained professionals. Ammonia:corn dry matter ratios for treatment range from 0.5% to 1.5% depending on the level of contamination, so the per-bushel cost of ammonia treatment is considerable even before adding the treatment apparatus and labor.
Q:What can I do with loads of corn that have been rejected at the elevator because of high aflatoxin contamination levels?
A:Depending on the level of contamination, aflatoxin contaminated corn may still be used as livestock feed. Aflatoxin can also be diluted at feeding by blending with non-contaminated feed, but such blending needs to be done with care to ensure the resulting mixture is below the target action level. The U.S. Food & Drug Administration (FDA) has guidelines for feeding aflatoxin contaminated corn (below; also online at:
Animal Feeds / Action level (parts per billion)Corn products intended for finishing beef cattle / 300
Corn products intended for finishing swine of 100 lb or greater / 200
Corn products intended for breeding beefand dairycattle, breeding swine, or mature poultry / 100
Corn products intended for lactating dairy animals / 20
Q: Can a mycotoxin binder be added to the ration to reduce risk of alfatoxin?
A: FDA has not approved mycotoxin binders, but classifies these feed additives as flow agents or anti-caking additives. For aflatoxin, the addition of clay based additives (such as aluminosilicates and benetonite products) can tie up some of the toxin, reducing its negative impact on cattle. For mycotoxins such as zearolene or T-2, the use of yeast cell wall products (called MOS) and enzymatic products can be effective.
Q:Can corn with high levels of aflatoxin contamination be used to make ethanol?
A:Aflatoxin does not interfere with ethanol production; however, aflatoxin may become even more concentrated in the distillers grains. Because these distillers grains are intended for animal feed, ethanol plants may reject corn with high levels of aflatoxin contamination.
Q:How is aflatoxin detected in corn?
A:Different tests are available that can detect and quantify the level of aflatoxin contamination in corn. The use of a black light may detect the presence of kojic acid, a precursor to aflatoxin, in corn, where the kojic acid will fluoresce (glow) in the presence of black light. This black light test is considered somewhat rudimentary, because it is not directly detecting aflatoxin, and may lead to a false positive or negative result. Some commercial kits are available that rely on immunoassays to detect aflatoxin. Analytical laboratories may use different techniques that are highly accurate, such as gas chromatography, mass spectroscopy, or thin-layer chromatography.
Q:Where can I have my grain tested for aflatoxin?
A:There are a number of laboratories and approved facilities that can test for aflatoxin. A list of certified testing facilities for aflatoxin in Illinois, Indiana, Ohio, and Michigan is available on-line at:
Prepared by:
Carl Bradley, Department of Crop Sciences, University of Illinois ()
Ted Funk, Department of Agricultural and Biological Engineering ()
Michael Hutjens, Department of Animal Sciences ()
Gary Schnitkey, Department of Agricultural and Consumer Economics ()