LAUSR

Aflatoxins are known to contaminate maize and other small-grain cereal crops both pre-harvest and during storage. Aspergillus spp. within the section flavi are principal producers of aflatoxins, fungal secondary metabolites (mycotoxins) that include aflatoxin B1 (AFB1). Chronic exposure to AFB1 and aflatoxin M1 (AFM1), a phase I metabolite of AFB1, have shown teratogenic, immunotoxic, mutagenic, and hepatotoxic activity and are classified as Group I carcinogens. Many jurisdictions limit the amount of AFB1 permissible per kg of feed material. For example, the United States allows between 20-300 µg total aflatoxins per kg of feed material, depending on the production stage of the animals and/or feed material. The European Union and Canada have tighter limits, with limits of 20 µg/kg of feed material and in the European Union 10 µg/kg for all complimentary and complete feeds. To further mitigate the impact of aflatoxins on animals, adsorbent materials that sequester aflatoxins can be added to animal feeds. Various studies have demonstrated the efficacy of a range of substances at reducing the impact of feed contaminated with mycotoxins, however these studies usually deal with feed contaminated at levels higher than those allowed in feed by the US and EU/Canada. The aim of this study was to investigate the effects a yeast cell wall preparations (YCW, Mycosorb®) on in vitro adsorption of mycotoxins; and in vivo, on AFB1 and AFM1 deposition in the liver of growing pigs fed diets contaminated with AFB1 at a level of 20 µg/kg. Adsorption evaluation performed in an acidic buffer environment established an aflatoxin B1 binding exceeding 92% in vitro. In vivo, thirty-two female pigs were randomly distributed to 16 pens with two pigs per pen. For one week the pigs were allowed to acclimatize to the housing and the basal diet containing no mycotoxin or YCW. The pigs were then fed diets containing AFB1 only (Control diet) or AFB1 + YCW (treatment diet) for 14 days, at which point the pigs were euthanized and their livers collected for mycotoxin quantification. No differences in productivity parameters (weight, weight gain, feed conversion ratio) were detected between the control and YCW treated animals. The results of the liver demonstrated that pigs fed diets supplemented with YCW had significantly (p< 0.05) less AFB1, AFM1 and AFB1 + AFM1 in their livers with respective concentrations of 47.0, 83.4 and 130.4 ng/kg compared to the mycotoxin challenge alone, with 60.6, 106.1 and 166.7 ng/kg respectively. These results indicated that even at low levels of contamination, YCW could adsorb aflatoxin B1 and significantly decrease the deposition of aflatoxins in the liver.