Besides prevention, the most common strategy for reducing animal's exposure to mycotoxins is to de- crease mycotoxins bioavailability by incorporating various mycotoxin-detoxifying agents in the feed, which targets a reduction of mycotoxin uptake and distribution to the blood and target organs. Depending on their mode of action, these feed additives may act by reducing the bioavailability of the mycotoxins (adsorbing agents also called binding agents, adsorbents, binders) or by degrading them into less toxic metabolites (biotransforming agents). Mycotoxin-adsorbing agents are large molecular weight compounds that are not digested by the animals and end up in the faeces. Adsorbing agents must be able to bind mycotoxins in contaminated feed without dissociating along the gastrointestinal tract of the animal, so that the toxin-adsorbing agent complex is eliminated via the faeces. This minimises the exposure of animals to mycotoxins (EFSA, 2009). Adsorbing agents can be mineral or organic compounds. Their mode of action is based on intermolecular interactions (toxin-binder) that depends on electrostatic/hydrophobic interactions (hydrogen or ionic binding and Van der Waals forces) and shape effects (planar or non-planar geometry), differing with the nature of the adsorbent as well as the type of mycotoxin. Many mycotoxins can occur simultaneously in the feed with various chemical and physical properties. They can differ a lot in terms of hydrophobicity/polarity and possible types of bonds (number and nature). The size of mycotoxins can be similar between families, but with very different 3D conformation and volume. For instance, aflatoxins are planar, zear- alenones are flexible and trichothecenes are globular and rigid molecules, though they all have comparable size. The total charges distribution and the size of pores or accessible surface of adsorbing agents also determine their efficacy to bind to different mycotoxins.
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