Food for thought (maybe not clear thought, but thought)

[Guest guest]

" Because of the identification of aflatoxin infested corn throughout the

Midwest in recent years, the FDA has issued guidelines that allow for the

interstate transportation of aflatoxin contaminated corn at levels above the

typical 20 ppb. "

Animals and Mycotoxins: Molds in Corn

Evidence of molds is typical under normal growing conditions, however, hail

damaged, drought and/or damp growing conditions contribute to excess molds on

maturing corn plants, according to Dr. Terry Mader, University of Nebraska

Extension Beef Specialist. Toxins produced by mold are called mycotoxins.

Aflatoxins and fusarium toxins, such as zearalenone and vomitoxin are

mycotoxins

of most concern to livestock producers. In general, aflatoxins are more

prevalent under warm, dry conditions while Fusarium toxins are more prevalent

under cool, damp conditions.

Generally, ruminants have a greater tolerance for mycotoxins and can handle

longer periods of low-level intake as compared to simple stomach animals. It

is postulated that the rumen microorganisms interact with to partially

degrade the toxins before they are absorbed. Sheep appear to excrete

significant

amounts of aflatoxin in their urine with a minimum of damage to liver and,

therefore, appear to be less susceptible to aflatoxin poisoning. Also, older

animals are less susceptible to mycotoxin toxicity than are younger animals.

Most

mycotoxins, and aflatoxin in particular, are difficult to remove from

feedstuffs. Ultraviolet irradiation and anhydrous ammonia under pressure will

reduce the toxicity of aflatoxins and, if continued long enough, will

deactivate

them entirely.

Dry heat can be used to reduce aflatoxin levels in contaminated corn.

Reductions from 60 to 90 percent in aflatoxin levels were observed when corn

kernels were heated to over 300 degrees F for approximately 12 minutes. High

temperatures may reduce feed value of corn, however. Also, cleaning or

screening

grain can remove as much as 50% of the toxins present. The degree to which

fermentation, through ensiling of the corn plant, will destroy mycotoxins is

not

clearly known. If ensiled, proper ensiling is important to prevent further

mold growth. Application of an inoculant to the green chop should enhance

fermentation and aid the ensiling process.

Because of the identification of aflatoxin infested corn throughout the

Midwest in recent years, the FDA has issued guidelines that allow for the

interstate transportation of aflatoxin contaminated corn at levels above the

typical

20 ppb. These guidelines are:

* Less than 20 ppb aflatoxins are allowed if the grain is destined for food

use by humans, for feed use by

immature animals or use by lactating dairy cows, or its destination is not

known;

* Less than 100 ppb aflatoxins if destined for breeding cattle, breeding

swine or mature poultry;

* Less than 200 ppb aflatoxins if destined for finishing swine 100 lb. or

heavier; or

* Less than 300 ppb aflatoxins if destined for finishing (feedlot) cattle.

State diagnostic laboratories and commercial laboratories with feed testing

facilities will usually test for mycotoxins.

By Dr. Rick Rasby, Professor of Animal Science

Animal Science, University of Nebraska - Lincoln

Institute of Agriculture & Natural Resources

Sharon Noonan Kramer

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