COUNTERACTING MYCOTOXICOSIS IN ANIMALS BY FEED ADDITIVES

Mycotoxins have become one of the most recognised feed chain contaminants, with hundreds of mycotoxins identified to date. Management of mycotoxins includes prevention, regulation, monitoring, decontamination, detoxification and animal treatments. Even with good management, unavoidably low levels of several mycotoxins can cause loss of feedstuffs, increased animal disease, reduced animal performance, and food residues. A promising approach to protect animals against the harmful effects of mycotoxin contaminated feed is based on the use of feed additives. These additives are defined as substances that, when included into contaminated feed, can adsorb or denature mycotoxins in the digestive tract of animals. Since 2009, the use of these substances is officially allowed in the European Union as technological feed additives. Depending on the mode of action, these additives may act either by degrading or transforming mycotoxins into less toxic metabolites (biotransformation) or by binding mycotoxins to their surface (adsorption). Mycotoxin adsorbents are the most studied feed additives and are successfully used worldwide to reduce the absorption of mycotoxins from the gastrointestinal tract and their distribution to blood and target organs. A number of products including indigestible adsorbent materials such as silicates, activated carbons, complex carbohydrates and others have been shown to be effective. Decreasing the bioavailability of aflatoxins by the inclusion of binding agents is particularly effective, as this group of toxins has a chemical structure which favours adsorption, especially by materials of mineral origin such as clay and zeolites. Ochratoxin A, zearalenone and fumonisin adsorption by biological adsorbents has been extensively studied due to the inefficiency of mineral adsorbents. Deoxynivalenol and T-2 or HT-2 toxins do not bind easily to a type of binding agents. So far, a mycotoxin adsorbent product that meets all the desirable characteristics is not available; most of them cannot adsorb a wide range of mycotoxins and may have adverse nutritional effects. Organic adsorbing agents such as yeasts have a well-known ability to stimulate the immune system, providing a good resistance to infectious diseases. An overview of the most important types of mycotoxin adsorbents will be presented together with the relevant effectiveness, problems, current trends and future perspectives.