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, including corn ear silage or high-moisture corn has had mold growth. These molds produce toxins that may have detrimental effects on feed performance. Insect damage and other stresses on the plant increase the 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.
Know the risks.
Aflatoxin is the best known and researched toxin. It is considered to be a carcinogen and is regulated by the Food and Drug Administration. If there is more than 20 parts per billion (ppb) in corn, it is considered contaminated for dairy cattle; milk must contain less than 0.5 ppb. Symptoms of aflatoxin poisoning include reduced growth, abnormal blood clotting, hemorrhaging, jaundice, reduced immune function and death.
Zearalenone is as an estrogenic compound that either causes animals to display a constant heat or inhibits cyclic activity. Producers who are developing breeding stock should not feed grains contaminated with zearalenone. Feed contaminated with zearalenone is a strong possibility this year because of the low temperatures and wet weather we have had. Symptoms include 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; vomiting; reduced reproduction, growth, milk production or egg production; poor feed efficiency; neurological problems; and increased morbidity or mortality.
Fumonisin is more prevalent in times of high humidity preceded by hot and dry weather. Fumonisin causes leukoencephalomalica in horses and pulmonary edema and liver damage in swine. Cattle and sheep are not as affected, but liver damage may still occur. Poultry are even more resistant.
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.
If moldy corn must be used, be cautious. Blend contaminated feed with clean feed to lower the mycotoxin levels. If corn is going to be ensiled, use an inoculant and do everything possible to promote fermentation. Feed a toxin binder, flow agent or conditioner.
Monitor dry matter intake, as many toxins will reduce intake slightly and can be detected with close monitoring. The incidence of bullers may increase due to estrogenic compounds or a reduced intake of MGA.
Ki Fanning is a ruminant nutritionist with Great Plains Livestock Consulting, Inc., in Eagle, Neb. Call him at (402) 781-9378 or visit www.GPLC-Inc.com.