Animal feed, including herbage, may be contaminated with organic and inorganic compounds and with particulates. Organic chemicals comprise the largest group and include plant toxins, mycotoxins, antibiotics, prion proteins, animal toxins and pesticides. Inorganic compounds include heavy metals and radionuclides. Particulates such as weed seeds and certain bacterial pathogens are common contaminants of feed.
Mycotoxin is a toxin produced by an organism of the fungus kingdom, which includes mushrooms, molds and yeasts. Most fungi are aerobic (use oxygen). Fungi are found almost everywhere in extremely small quantities because of their spores, and are most commonly microscopically small. They consume organic matter, wherever humidity and temperature are sufficient. Mycotoxins are secondary metabolites produced by certain species of fungi growing under specific environmental conditions.