Kinetics and metabolism of deoxynivalenol (DON) and zearalenone (ZEN) in the pig: Consequences for diagnosis of exposure and intoxication

DON and ZEN often co-contaminate cereal grains used as feedstuffs. These toxins are highly relevant in pig feeding as this species responds especially sensitive to the presence of DON and ZEN with a decrease in feed intake and reproductive disorders, respectively, especially when critical contaminations in feed are exceeded. The European guidance values for critical DON and ZEN concentrations in diets for pigs amount to 0.9 mg DON/kg for all pig categories, and 0.1 and 0.25 mg ZEN/kg for piglets/gilts and sows, respectively (CEC 2006). Both from a practical and from forensic perspective often raises the question on whether the detection of mycotoxins in physiological samples has relevance for the occurrence of more or less pronounced toxid effects or, in other words, whether there are useful correlations between the toxin concentrations and toxic effects. From a methodological viewpoint dose-response studies are helpful which relate the toxin concentration in the diets to the resulting toxin cencentrations in the physiological specimens as indicators for the inner exposure of the animal. Based on the kinetic characteristics of DON and ZEN various physiological samples can principally be used for evaluation of exposure, such as blood, bile, urine and faeces. However, in the view that both toxins differ markedly in kinetics there also exists differences in the usefulness of these matrices as indicators for exposure. Moreover, the metabolism of the toxins needs to be considered especially in the view that metabolites might differ markedly in toxicity. DON might be metabolised to de-epoxy-DON while ZEN can principally be converted to a number of metabolites, from which alpha- and beta-zearalenol (ZEL), zearalenone (ZAN), and alpha- and beta-zearalenol (ZAL) are the most important ones.