Aerobic and anaerobic in vitro testing of feed additives claiming to detoxify deoxynivalenol and zearalenone

Deoxynivalenol (DON) and zearalenone (ZEN) are mycotoxins produced by fungi of the genus Fusarium which frequently contaminate maize and grain cereals. Mycotoxin-contaminated feed endangers animal health and leads to economic losses in animal production. Several mycotoxin elimination strategies, including the use of commercially available DON and ZEN detoxifying agents, have been developed. However, frequently there is no scientific proof of the efficacy of such adsorbents and degrading products. We therefore tested 20 commercially available products claiming to detoxify DON and/or ZEN either by biodegradation (4 products) or a combination of degradation and adsorption (16 products) under aerobic and anaerobic conditions at approx. pH 7. Under the applied conditions, a complete reduction of DON and consequent formation of the known non-toxic metabolite DOM-1 was exclusively observed in samples taken from the anaerobic degradation experiment of one product. For all other products, incubated under aerobic and anaerobic conditions, a maximum DON reduction of 17% after 72h of incubation was detected. Aerobic and anaerobic incubation of only one tested product resulted in complete ZEN reduction as well as in the formation of the less-toxic metabolites DHZEN and HZEN. With this product, 68-97% of the toxin was metabolised within 3h. After 24h, a ZEN reduction >= 60% was obtained with four additional products during aerobic incubation only. Six of the 20 investigated products produced alpha- and/or beta-ZEL, which are metabolites showing similar oestrogenic activity compared to ZEN. Aerobic and anaerobic degradation to unknown metabolites with unidentified toxicity was obtained with 10 and 3 products, respectively. The results of our study demonstrate the importance of in vitro experiments to critically screen agents claiming mycotoxin detoxification.