Aflatoxin in Corn

What a weather anomaly this year has been!  It started this spring with the bomb cyclone in March in the western part of Nebraska and the flooding on the central and eastern portion of the state from the rapid melting and rains.  Since then, much of the state has been wet or flooded.

As silage harvest continues and corn harvest begins, mycotoxin challenges and issues may arise.  Mold produce mycotoxins.  It is not the molds themselves that impact animal health, it is the mycotoxins that negatively impact animal health. 

One common mycotoxin is Aflatoxin.  Aflatoxin is produced by two molds, Aspergillus flavus and A. parasiticusA. parasiticus causes the most aflatoxin issues in the United States.  High heat, relative humidity and drought are ideal conditions for aflatoxin growth during pollination and as kernels mature.  On corn in a field, mold growth will appear as gray-green or yellow-green mold growing on corn kernels in the field or storage.

Long-term consumption of low levels of mycotoxins may contribute to chronic problems including reduced feed intake, reduced nutrient absorption and impaired metabolism, suppressed immunity, and altered microbial growth. 

Before feeding grains to livestock, it is recommended to test feeds for mycotoxins. Contact the laboratory you or your nutritionist use to determine if they test for mycotoxins.  Iowa State University Extension and Outreach developed a Mycotoxin Grain Testing Directory of laboratories, both commercial and University based, that test for mycotoxins.  The table below outlines the FDA guidelines for using contaminated grain in livestock feed. 

In the past two years, there have been aflatoxin issues on dairy farms. Two cases where aflatoxins caused deaths of dairy cattle of all ages and another case where milk in the bulk tank tested positive because of aflatoxins in corn.  After it was determined these cases were caused by aflatoxins, the dairies disposed of the contaminated grain and silage and began feeding a binder.  Within days of feeding the binder, the animals began to positively respond to the binders in the ration.  

Intended use Afloxtoxin Level (ppb)
Corn for dairy cows <20
Corn for finishing beef cattle <300
Corn for breeding beef cattle, breeding swine or mature poultry <100
Immature animals (goats, sheep and pigs less than 4 months of age; cattle and equine less than 6 months of age) <20

If you have mycotoxins in your feed, you may consider feeding a binder such as sodium bentonite or calcium aluminosilicate.  The theory is that the binder decontaminates mycotoxins in the feed by binding them strongly and preventing absorption of mycotoxins in the digestive tract.  Although these products are approved for use in feed, the FDA does not recognize these binders as aflatoxin management strategies. 

Additional Resources

Mold and Mycotoxin Issues in Dairy Cattle: Effects, Prevention and Treatment –

Aflatoxins in Corn – University of Missouri Extension

Reducing Aflatoxin in Corn During Harvest and Storage - University of Georgia Extension