Aflatoxin B1 Adsorption to Clays and Toxicity Reduction in Animal Feed.

Aflatoxins are chemical compounds that are toxic and carcinogenic to animals and humans which are produced by fungi in crops, such as corn and peanuts.  Clay minerals, such as montmorillonite, are used as feed additives and some clay additives can effectively reduce aflatoxicosis in animals caused by contaminated feed.  Animal feeding studies have shown that some feed additives more effectively reduce aflatoxicosis than others. Less expensive methods, such batch aflatoxin adsorption isotherms from water, are used to screen potential feed additives.  However, feed additives that effectively adsorb aflatoxins from water may not reduce aflatoxicosis when added to animal feed.  Activated carbon readily adsorbs aflatoxins from water, but does not effectively prevent aflatoxicosis when added to animal feed.  Batch adsorption isotherms from water do not model the digestive tract where soluble compounds might interfere with aflatoxin adsorption.  Ingested food, such as corn, can affect pH and release dissolved organic compounds.  Aflatoxin adsorption procedures to screen potentially good feed additives might be modified to better correlate with animal feeding studies. Methanol/water extractions are commonly used to extract aflatoxins from feed grains to measure the aflatoxin content.  Aflatoxin isotherms using methanol extractions with a corn meal matrix yielded relative sorption values consistent with animal feeding studies.  In isotherms using methanol extraction and corn meal, activated carbon retained much less aflatoxin than a clay-based feed additive that reduced aflatoxicosis in feeding studies. Modified aflatoxin adsorption isotherms can more effectively select feed additives that will reduce aflatoxicosis when added to feed.