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Mycotoxins vs. Molds

Kristine Koepplin Livestock Nutrition Specialist

Are Mycotoxins and molds the same? What is a Mycotoxin versus Mold? Often these two terminologies get used interchangeably, and often considered the same. However, they are not the same. Mycotoxins are a secondary metabolite (or natural substance) produced by molds under stressed conditions. Scientists do not know how many mycotoxins may exist at this point, even though more than 500 different mycotoxins have identified. Mycotoxins can be found on many different types of forages and grains. The growth of mycotoxins on feedstuffs is typically promoted by heat and moisture. However, mycotoxins can be produced by other stress conditions like drought as well as late harvest due to wet weather.  

Different mycotoxins cause different diseases and are different from each other. Diseases in animals caused by mycotoxins are called mycotoxicoses. Mycotoxicoses occur when one or more mycotoxin enters the body usually by consumption of contaminated feed. The illness in the animal is caused by actions of mycotoxins on the cells in the body and the immune system is not stimulated to fight off the mycotoxicosis. Mycotoxicoses are not contagious and do not spread from animal to animal with the herd or pen, however multiple animals are often affected due to the contaminated feeds.

Diseases directly caused by mold or fungal infections are called mycoses. Mycoses occur when a mold or fungi infect tissues of the body. Mycoses can be contagious, spreading from animal to animal. Molds begin to grow in the body or on the body after the infections are started. The animal’s immune system may be stimulated to fight of the infection of a mycoses. Ringworm and athlete’s foot are common mycoses.

Diagnosis of mycotoxicoses is typically difficult as mycotoxins rarely can be found in the tissues of the animals due to limited availability testing offered. Therefore, diagnosis depends heavily on testing the forages or grain, which collecting representative samples of the feeds are very important. Molds are often visible on the forages or grains and be a variety of colors. The color or level of mold does not reflect the type or level of mycotoxins. Mycotoxins can be present when molds are not visible. Mold counts do not equal mycotoxins. It is recommended to test grains and forages using a mycotoxin analytical test to identify mycotoxin species in your feedstuffs. By the time you can see mold growth, the nutritional value is compromised and most of the digestible nutrients are gone.

The most common mycotoxins are: aflatoxin, deoxynivalenol (DON) or vomitoxin, zearalenone, T-2 Toxin and fumonisin. Mycotoxins in high enough concentrations can cause reduced feed intake, poor performance and production, decreased immune function and increased susceptibility to diseases. If you have any further questions about mycotoxins or testing any forages and grains for mycotoxins, contact your local nutrition consultant or veterinarian.  

Thank you and have a safe winter!
Kristine Koepplin
Livestock Nutrition Specialist
New Salem & Elgin


Carlson, M. NebGuide. Understanding Fungal (Mold) Toxins (Mycotoxins). http://extensionpublication.unl.edu.
Griffin, D. Food Animal Practice. Cow-Calf Operation Beef Quality Assurance. P589-590.
Drouin. P, Lallemand Animal Nutrition. Silage Management Technical Guide.P. 50-52.

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