Phytates, Phytase, and Fumonisin B1 Adsorption to Feed Additives During Simulated Gastrointestinal Digestion of Corn Meal.

Fungi produce toxic compounds (mycotoxins) in crops, such as corn, wheat, and peanuts.  Fumonisins are mycotoxins toxic to humans and animals that frequently contaminate corn.  Animal feeding studies have shown that feed additives can effectively bind some mycotoxins in feed and prevent toxicity.  Fumonisin B1 (FuB1) is the most toxic and most common fumonisin.  Fumonisins are anionic compounds that adsorb to anion exchange materials, such as cholestyramine.  Animal feeding studies have shown that cholestyramine can bind fumonisins in feed and decrease toxicity to animals. Phytates are soluble compounds in corn (0.8 to 2.2%) and other grains that exist as multivalent anions at weakly-acidic to alkaline pHs. Phytates cannot be digested by humans, pigs, or other non-ruminant animals.  Low-phytate corn varieties were produced to improve phytate-phosphorus absorption from feed by non-ruminants and reduce soluble phosphate concentrations in manure.  Anionic phytates adsorb to anion exchange materials and could reduce fumonisin adsorption to feed additives.  Adsorption isotherms indicate that phytates in corn meal can greatly decrease FuB1 adsorption to cholestyramine.  Ferric chloride addition to precipitate phytates or phytase enzyme added to decompose phytates in corn meal increased FuB1 adsorption.  This suggests that fumonisins in low-phytate corn would more readily adsorb to cholestyramine or other feed additives.  Simulated gastrointestinal digestions of FuB1-contaminated corn meal with and without phytase were performed to model the effects of digestion on fumonisin binding to feed additives in regular corn versus low-phytate corn.