This year's drought has brought numerous challenges to cattlemen. Shortages of grass and water forced cow culling and sent many calves to the sale barn earlier than planned. The most recent challenge cattlemen are facing is high feed costs combined with the possibility of aflatoxin in the corn crop.
"It is a common misconception that the olive-green mold known as aspergillus automatically results in aflatoxin," said University of Illinois Extension beef educator Travis Meteer. "This is not the case. If you find mold present on your corn, it needs to be tested for aflatoxin."
Meteer cautioned that aflatoxin can also be found in Dry Distillers Grains with Solubles (DDGS) produced from infected corn. "Aflatoxin is concentrated in the fermentation process and thus the levels in DDGS can be dangerous," he said. "Testing corn and corn co-products for aflatoxin is recommended."
Livestock are usually the market for mycotoxin-infected commodities, he added. "Livestock can tolerate some level of mycotoxin, but levels above legal limits can cause problems in livestock. Reduced performance, immunosuppression, liver damage, and in extreme cases even death can be the result of feeding high levels of aflatoxin," Meteer said.
The chart below illustrates the approved levels in livestock.
Intended Use Aflatoxin Level (ppb)
Finishing(feedlot) cattle < 300
Finishing swine < 200
Breeding cattle or swine < 100
Dairy cattle, young cattle or swine < 20
Intended use not known < 20
Human food < 20
Livestock, especially finishing cattle, will be the end user of much of the aflatoxin-infected corn, Meteer said. "Caution and management are crucial to ensure that negative results do not occur from feeding this toxin-bearing feed."
Meteer recommends that the storage of corn that has aspergillus present needs to be dried down to less than 14 percent moisture to limit mold growth. Also, cool the grain down after drying and use aeration to control temperature. Mold inhibitors may also be applied to corn to reduce mold growth.
Test and monitor aflatoxin levels of corn to be fed to livestock. Blending aflatoxin-bearing corn with clean corn at the time of feeding can be a good practice to reduce aflatoxin levels in the diet.
Dilution is the solution. Blending should only occur directly before feeding. Blended corn is not legal for resale. Blending corn before feeding could result in contamination of clean corn.
Toxin-binding agents can also be incorporated into a ration.
"Many studies have shown that phyllosilicate feed additives bind toxins (clays, sodium bentonite, aluminosilicate)," Meteer said. "These products can bind toxins and ensure they are not absorbed by the animal. Many feed mills will include them in feeds if they are using corn with traces of aflatoxin. It would be a good idea to use toxin binders in a ration that includes corn that has high levels of aflatoxin," he said.
Grazing cornstalks where aflatoxin was found in corn should be of a lesser concern than feeding the corn. However, cornfields that have down corn or lots of ear drop coupled with aflatoxin being present may have potential to be dangerous to cattle. The less corn left in the field the better in this situation, Meteer said. Also, baling cornstalks from fields that have aflatoxin is discouraged.
Meteer said that corn silage or husklage that contains aflatoxin can also be a concern. However, if properly ensiled, the environment should not be conducive to mold growth. In the case of corn husklage, a byproduct of the seed corn industry, if it is not ensiled properly, mold growth may occur and aflatoxin could be a concern.
"Producers should dry corn below 14 percent moisture to reduce mold growth, be prepared to blend aflatoxin corn with clean corn directly before feeding, and consider toxin binders as a feed additive," Meteer said. "Identification of molds, testing for aflatoxin, and proper management and storage considerations will be vital to ensure livestock performance is maintained and legal limits are not exceeded."
Source: University of Illinois