Evaluation of Mycotoxin Binders

Lon W. Whitlow Department of Animal Science North Carolina State University Raleigh, NC 27695 Phone: 919-515-7602 Fax: 919-515-2152 Email: [email protected] Summary Considerable research has been directed at finding methods to prevent toxicity of mycotoxins. Some of the approaches have included mycotoxin separation from contaminated feeds, detoxification and inactivation. Detoxification and inactivation methods include the use of binders or sequestering agents added to feed as an approach to reduce toxicity of mycotoxins by reducing reactivity of bound mycotoxins and reducing their intestinal absorption. Substances used as mycotoxin binders include indigestible adsorbent materials such as silicates, activated carbons, complex carbohydrates and others. The use of binders offers an approach to salvaging feeds with low levels of mycotoxins and to protecting animals from the background levels of mycotoxins that, although low in concentration, routinely occur and may cause chronic disease problems and losses in performance. A binder product that meets all the desirable characteristics is not available, but the potential currently exists for practical judicial use of mycotoxins binders for reducing mycotoxin exposure to animals. Various materials offer the potential to bind mycotoxins in feed. Silicates bind aflatoxin and some other mycotoxins, such as sterigmatocystin, which has a chemical structure similar to aflatoxin. There are many different silicates and they differ in mycotoxin binding. Chemically modification of silicates can increase binding to mycotoxins such as deoxynivalenol and zearalenone. Activated carbon (charcoal) has produced variable binding results, perhaps because of differences in physical properties of the test product. Aflatoxin binding by activated charcoal has been variable, but mostly positive. Charcoal may also bind zearalenone and deoxynivalenol. Complex indigestible carbohydrate polymers derived from yeast cell walls are shown effective in binding aflatoxin and restoring performance to animals consuming multiple mycotoxins (generally Fusarium produced). Bacterial cell walls also have potential to bind mycotoxins, but limited research has been conducted. Inorganic polymers such as cholestyramine and polyvinylpyrrolidone also have binding potential. No adsorbent product is approved by the U.S. Food and Drug Administration (FDA) for the prevention or treatment of mycotoxicoses. Several of these adsorbent materials are recognized as safe feed additives (GRAS) and are used in diets for purposes such as flow agents and pellet binders. Introduction Molds are filamentous fungi that occur in many feedstuffs including grains (Russell et al., 1991) and forages (Lacey, 1991). Molds can infect animals, especially during stressful periods when they are immune suppressed, causing a disease referred to as a mycosis. Molds also produce mycotoxins, which can cause a mycotoxicosis or toxic response in animals exposed primarily by consuming mycotoxin-contaminated feeds. The FAO has estimated that worldwide about 25% of crops are affected annually with mycotoxins (Jelinek et al., 1989). Surveys reveal sufficiently high occurrences and concentrations of mycotoxins to suggest that they are a constant concern (Whitlow et al., 1998). Molds are present throughout the environment and mycotoxins can be formed on crops in the field, during harvest, or during storage, processing, or feeding. Mold spores are present in materials such as soil and plant debris, ready to infect the growing plant in the field. Field diseases are characterized by yield loss, Proceedings of the 4th Mid-Atlantic Nutrition Conference. 2006. Zimmermann, N.G., ed., University of Maryland, College Park, MD 20742.