Excretion kinetics and metabolism of zearalenone in broilers in dependence on a detoxifying agent

Two experiments were carried out with male broilers to examine excretion kinetics of zearalenone (ZON) and its metabolites and their occurrence in blood plasma and bile fluid after a single oral dose of ZON (approximately 6 micrograms/kg BW) from naturally contaminated wheat (406 micrograms ZON per kg). In addition, this ZON bolus was administered either in the absence or presence of a detoxifying agent (Mycofix-Plus, Biomin GmbH, Herzogenburg, Austria). Specimens were sampled after administration of the zearalenone bolus at different times of up to 48 h. Excretion of zearalenone and alpha-zearalenol as the only detectable metabolite of ZON peaked at approximately 6.5 h after administration of the bolus. Cumulative excretion of both substances amounted to approximately 58% of ZON intake after 48 h, when a plateau was achieved. The incomplete recovery could have been due to a partial total degradation of ZON in the digestive tract, undetected sulfate conjugates of ZON or its metabolites, to other unknown and undetected metabolites or to incomplete analytical recovery from the matrix, and needs to be examined further. Peak concentrations of zearalenone and alpha-zearalenol in bile were detected in the time period of approximately 2 to 6 h after bolus, whereas ZON and metabolite concentrations in blood plasma were around or lower than the detection limits. Mycofix-Plus supplementation seemed to have only minor or no effects on the parameters examined.