Aflatoxins and fumonisins in corn

“This is not a crisis, but it is a situation that needs to be monitored and managed,” said Jim Stack, UNL plant pathologist and moderator of an October 9 videoconference on the topic. Specialists from the University of Nebraska, Nebraska Department of Agriculture, and the Lincoln Grain Inspection Service explained how mycotoxins develop and addressed the regulations, sampling, testing, and management of grain contaminated with mycotoxins. The videoconference is available for viewing on-line at http://g2.unl.edu:8080/ramgen/programs/mj/mycotoxin.rm. Many Cooperative Extension offices also may have copies of the videoconference available on videotape.

Speakers on the videoconference were:

Dr. Jim Stack, Extension plant pathologist at the UNL South Central Research and Extension Center, who specializes in corn diseases;

Dr. Mike Carlson, analytical chemist in the UNL Veterinary Diagnostic Toxicology Laboratory, who discussed the development of mycotoxins and the effect on animals;

Dave Reeder, manager of the Lincoln Inspection Service, who discussed testing options and the results of the tests they’ve conducted of suspect grain;

Ken Jackson, program manager for the feed and fertilizer section, Nebraska Department of Agriculture, who discussed regulations on testing, blending and sale of contaminated crop;

Tom Jensen, administrator of the Laboratory Division of the Nebraska Department of Agriculture, who discussed testing options and results of their tests;

Dr. Galen Erickson, UNL Extension feedlot specialist, who will address some of the management issues; and

Dr. Duane Reese, UNL Extension swine specialist, who discussed feeding implications for swine.

Quick takes While mycotoxins develop from grain molds, the presence or absence of visible mold does not correlate with the presence of mycotoxins. Mycotoxins can develop both pre- and post-harvest and testing is necessary to confirm their presence. A number of contaminants, including insects and molds, may appear florescent under a black light. Further testing is required to determine the source of the florescence. This year's high incidence of aflatoxin was due to the drought and high temperatures. Avoiding plant stress, even in irrigated corn, can significantly reduce the potential for the development of mycotoxins. Fines and screens of contaminated grain and damaged kernels may have especially high levels of mycotoxins. Be sure to test these separately before feeding to livestock. Before sampling for mycotoxins, contact your grain tester for recommendations on sampling technique, amount and how to submit the sample. Generally, a sample of 5 or more pounds of grain is best. Inhalation of aflatoxin-contaminated dust has been associated with adverse health effects in humans. Workers should wear dust masks when moving or processing grains and respirators when working in silos or other confined areas containing grain. Fumonisin contamination became an issue several years when the USDA issued revised standards, based on recent research, limiting its level in corn. Take one grain from 250,000-285,000 pounds of sand -- that’s comparable to finding one part per billion when testing for contaminants.

Mycotoxins are toxins produced by molds under certain conditions. Aflatoxin, fumonisin, vomitoxin & zearalenone are all mycotoxins, but their chemical and toxicological characteristics differ. They are found in or on the grain, but not in the foliage.

Animal susceptibility to adverse health effects varies by species, but all animals are susceptible. Age and health status of individual animals will affect susceptibility; animals that are young, old, or have liver disease are more susceptible. Effects depend upon amount and length of exposure, and the animal's age, nutritional status, health, and species.

Management

When storing corn, reduce grain moisture to less than 15% in the first 48 hours. This will not decrease existing mold, but in most cases it should prevent it from increasing. To minimize problems in long-term storage, a low storage temperature (less than 40^oF) and good air circulation are critical to maintain a uniform temperature and low relative humidity. Insect management also is critical to maintaining condition in storage since insects may vector the fungi.

Nebraska Department of Agriculture regulations,
including allowable limits and blending of aflatoxin-contaminated grain

"The Food and Drug Administration has adopted, by policy as outlined in Compliance Policy Guide 683.100, certain levels of aflatoxin in corn. These are the same levels applied by the Nebraska Department of Agriculture in regulating aflatoxin in corn and are listed below:

Naturally occurring aflatoxin levels
Action Level	Commodity	Species
20 ppb or less	Corn	Human food, dairy, and immature animals
100 ppb or less	Corn	Breeding cattle, breeding swine, and mature poultry
200 ppb or less	Corn	Finishing swine greater than 100 lbs. in weight
300 ppb or less	Corn	Finishing beef cattle
200 ppb or less	Corn	Finishing swine greater than 100 lbs in weight
300 ppb or less	Corn	Finishing beef cattle

Naturally occurring fumonisin levels
5 ppm	Equids and rabbits
20 ppm	Swine and catfish
30 ppm	Breeding ruminants
100 ppm	Poultry
10 ppm	Other livestock and pets

Blending Policy/Intrastate Commerce

"We will not object to blending corn with higher levels of aflatoxin with corn found to have lower or negative aflatoxin levels intended as animal feed for finishing beef cattle or finishing swine (greater than 100 lbs. in weight.) The following requirements must be met:

"The producer/user must:

• Test the finished blend to verify that the resulting level of aflatoxin does not exceed 300 ppb for finishing beef cattle or 200 ppb for finishing swine (greater than 100 lbs.).
• Collect a representative sample -- no less than 5 lbs in a paper bag (good idea to double bag) and directly transport or mail to a laboratory for testing.
• Keep the test results for no less than one year.

"The shipper/seller must, in addition to the above requirements:

Provide a label or invoice stating the level of aflatoxin in the finished product.

Designate on the invoice or label what species the product is intended to be fed.

Have some assurance that the buyer is aware of the level and will use it accordingly.

Blending Policy/Interstate Commerce

"We will not object to blending corn with levels of aflatoxin above 300 ppb with corn found to have lower or negative levels of aflatoxin intended for feed for beef finishing cattle. The following requirements must be met:

• The seller must analyze each shipment of blended corn to identify the level of aflatoxin in the final product.
• The seller must keep the test results for no less than one year. The same sampling procedures apply as stated above.
• Provide a label or invoice stating the level of aflatoxin in the finished product.
• Designate on the label or invoice what species the product is intended to be fed.
• Have some assurance that the buyer is aware of the level and will use it accordingly.

Additional resources

Blending, Testing Key To Managing Corn Molds This Harvest Season, a news release from the UNL Institute of Agriculture and Natural Resources based on the Oct. 9 videoconference.

Immediate drying, bin aeration can minimize effects of mycotoxins in corn, a story in the Sept. 20 CropWatch

Limiting aflatoxins, a sidebar in the Sept. 20 CropWatch