12: Mycotoxins in the feed and animal products

Abstract

Mycotoxins are secondary metabolites of fungi, which are toxic to animals at certain concentrations. Hundreds of mycotoxins have been identified but only a few have been extensively studied. The primary classes of mycotoxins are aflatoxins, zearalenone, trichothecenes, including deoxynivalenol, fumonisins, and ochratoxin A. Certain fungi (field fungi) can grow and produce mycotoxins in a large number of growing crops while other mycotoxins are produced during improper storage favourable for fungal growth. Diseases resulting from the consumption of mycotoxins are called mycotoxicosis. They often cause syndromes not readily identifiable, the condition is not contagious, treatment with antibodies or other drugs has little effect and outbreaks occur under conditions conducive for fungal growth. Several mycotoxins are carcinogenic. In general, consumption of mycotoxins results in reduced animal performance including decreased production of flesh or eggs in poultry, milk in dairy cows and meat in pigs and beef cattle. Many of the mycotoxins are detoxified in the liver and excreted in the urine or faeces while some such as aflatoxin B1 becomes fixed in animal tissues. The transfer of mycotoxins such as the aflatoxins and ochratoxin A into edible animal products (milk, meat, offal, eggs) can have detrimental effects on human health. Both pre-and post-harvest controls have been effective at reducing mycotoxin concentrations and bioavailability in feedstuffs. Many different types of binding agents (adsorbents/ absorbents), biotransforming agents and other treatments have been shown to be variably effective in reducing mycotoxins bioavailability. There is a need to develop rapid, accurate and inexpensive feed tests for mycotoxins; variety of crops that are resistant to fungal infections and new and more effective treatments to reduce mycotoxin pathogenicity caused by the consumption of contaminated grains or feed. Modified in-vitro and in-vivo methods should be developed that can accurately and inexpensively evaluate the efficacy of mycotoxin treatment agents.