Mycotoxicosis is caused by ingestion of toxic substances produced by molds growing on feed, feed ingredients and possibly litter. Several types of fungi produce toxins that may cause problems in poultry, but of primary concern are substances produced by the Aspergillus flavus fungi and are thus called aflatoxins. Aspergillus flavus is a common mold that grows on many substances, and grows especially well on grain and nuts. Several other fungi also produce toxins that cause the disease. The B 1 toxin is the most toxic and is of greatest concern to the poultry industry.
Mold toxins cause a wide variety of signs, many difficult to recognize.
Diagnosis is difficult because characteristic lesions usually are not present, and detection of the toxin is not conclusive. Molds are widespread in nature. Standing grains and other feed substances are frequently infected with toxin-producing molds prior to harvest. The key is proper storage to control moisture and temperature to reduce growth of the molds while in storage. Although the mold is present, it cannot produce toxic products unless allowed to grow freely.