Mycotoxins

Mycotoxins and Animal Health

Although the following section emphasizes the effects mycotoxins exert on animal health and performance, mycotoxins may also be a hazard to human health since animal products consumed by people may contain mycotoxin residues. While healthy animals tend to "filter out" or detoxify many of the mycotoxins to which they are exposed, in our consumer-oriented society the issue of mycotoxin residues in milk and animal tissues should not be ignored.

Mycotoxins produce a wide range of harmful effects in animals. The economic impact of reduced animal productivity, increased incidence of disease due to immunosuppression, damage to vital organs, and interferences with reproductive capacity is many times greater than the impact caused by death due to mycotoxin poisoning. In comparison to other animals, poultry species tend to be resistant to the effects of fumonisin, deoxynivalenol, and zearalenone. However, the presence of these mycotoxins within poultry rations is an indication that mold activity has occurred in the ration or in the ingredients within the ration. Since mold activity can generate numerous other mycotoxins as well as reduce the nutritive value and palatability of feeds, the presence of fumonisin, deoxynivalenol, or zearalenone in poultry feeds is cause for concern.

While young animals are most susceptible to the effects of aflatoxin, all ages are affected; and clinical signs include gastrointestinal dysfunction, reduced productivity, decreased feed utilization and efficiency, anemia, and jaundice. Nursing animals may be affected by exposure to aflatoxin metabolites secreted in the milk. Aflatoxin causes a variety of symptoms depending on the animal species. However, in all animals, aflatoxin can cause liver damage, decreased reproductive performance, reduced milk or egg production, embryonic death, teratogenicity (birth defects), tumors, and suppressed immune system function, even when low levels are consumed.

Deoxynivalenol (DON) is, perhaps, the most commonly detected Fusarium mycotoxin. DON has been associated with reduced milk production in dairy cattle, vomiting by swine consuming contaminated feed or their refusal to eat feed containing the toxin, and inhibiting reproductive performance and immune function in several animal species. In addition, DON levels greater than 500 ppb have been associated with numerous other field problems.

Zearalenone mimics the effect of the female hormone estrogen and, at low doses, increases the size or early maturity of mammary glands and reproductive organs. At higher doses zearalenone interferes with conception, ovulation, implantation, fetal development, and the viability of newborn animals.

T-2 toxin and its chemical relatives cause irritation, hemorrhage, and necrosis throughout the digestive tract, depress the regenerative process in the bone marrow and spleen, impair immune system function, and cause changes in reproductive organs. Affected animals show signs of weight loss, poor feed utilization, lack of appetite, vomiting, bloody diarrhea, abortion, and (in severe cases) death.

Fumonisin is a mycotoxin which has only recently been discovered. Thus it has not been extensively studied. Nonetheless, it is known that in most animals fumonisin impairs immune function, causes liver and kidney damage, decreases weight gains, and increases mortality rates. Fumonisin also causes leukoencephalomalacia in horses and respiratory difficulties in swine. In some animals fumonisin can also cause tumors.

Prepared by

Mary Beth Genter, Extension Toxicology Specialist
Winston M. Hagler, Director of NCSU Mycotoxin Laboratory
Jeff A. Hansen, Extension Animal Science Specialist
Bob A. Mowrey, Extension Animal Science Specialist
Frank T. Jones, Editor, Extension Poultry Science Specialist
Matt H. Poore, Extension Animal Science Specialist
Lon W. Whitlow, Extension Animal Science Specialist

http://www.ces.ncsu.edu/gaston/