Watch for Molds and Mycotoxins

Published on: 09:43AM Jan 25, 2010


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Ki Fanning, Ruminant Nutritionist

The 2009 harvest season has proven to be one of the most difficult in recent memory and we will have to deal with the results for the next 12 months. The wet corn left in the fields would seem to be a good feed source. However, much of the corn that has been harvested and that has yet to be harvested as earlage or high moisture corn has had mold growth. These molds produce toxins that may have detrimental effects on performance. Insect damage and other stresses on the plant increase potential for mold growth.

Distillers grains will not destroy the toxins; in fact the process will triple the concentration of toxins just as it does the protein. Gluten feed on the other hand is a product that comes from a food grade plant; therefore, the corn is carefully screened prior to entry into the system.This ensures that the products manufactured for human consumption are not contaminated; consequently neither is the gluten feed.

Aflatoxin is the most well known and researched toxin.  Aflatoxin is considered a carcinogen and therefore, is regulated by the FDA.  If over 20 ppb in corn, the corn is considered contaminated for dairy cattle; milk must contain less than 0.5 ppb.  Symptoms of aflatoxin poisoning are: reduced growth, abnormal blood clotting, hemorrhaging, jaundice, reduced immune function, and death.

Zearalenone is as an estrogenic compound that may either cause animals to display a constant heat or may inhibit cyclic activity. Therefore, if developing breeding stock, grains contaminated with Zearalenone should not be fed. Zearalenone contamination is a strong possibility this year because of the lower temperatures and the wet weather we have had. Symptoms of this toxin are: reduced conception rates, poor feed efficiency, swelling of female reproductive organs, reduced milk production, reduced growth rate, and increased morbidity or mortality.

Vomitoxin is produced by the pink mold that grows in warm rainy weather. Lower temperatures may increase toxin production once the corn or small grain is infected. This toxin’s symptoms include diarrhea, reduced reproduction, vomiting, reduced growth, milk production or egg production, poor feed efficiency, neurological problems, and increased morbidity or mortality.

Fumonisin is more prevalent during periods of high humidity when preceded by hot and dry weather. Fumonisin cause leucoencephalomalica in horses and pulmonary edema and liver damage in swine. Cattle and sheep are not affected to as great of an extent, however liver damage may still occur. Poultry are even more resistant than cattle and sheep. The T-2 Toxin causes digestive upsets, hemorrhage of the intestine, poor growth and feed efficiency, bloody diarrhea, and an increase in morbidity and mortality.  

Table 1.  Mycotoxin toxic level






Aflatoxin, ppb





Zearalenone, ppb





Vomitoxin, ppb





Fumonisin, ppb





T-2 Toxin, ppb





If the corn must be used for feed, please consider these suggestions.  If it is going to be ensiled use an inoculant, pack well, and cover the pile (do everything possible to promote fermentation). Feed a toxin binder or flow agent or conditioner (call for more information on this). Monitor dry matter intake as many of these toxins will reduce intake slightly and can be detected if intakes are monitored. The incidence of bullers may increase either due to estrogenic compounds or a reduced intake of MGA. It is very important to test for the mycotoxins. Blend the feed with other unaffected feeds to lower dietary levels of mycotoxins. 

For additional information, testing supplies, or diet formulation please give us a call at (402) 781-9378.

-Dr. Ki Fanning is a ruminant nutritionist at Great Plains Livestock Consulting, Inc. The consulting service was founded in 1998 by Dr. Ki Fanning with the goal of becoming the premier animal agricultural consulting company for feed manufacturers, producers, and entities engaged in the areas of livestock production, with the reputation of the highest integrity and quality of service.

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