LAUSR

European Union prohibited the use of anabolic agents in food producing animals since 1988. An efficient control of abuses is guaranteed not only by highly performing analytical methods, but also by knowledge of metabolic pathways, kinetics of elimination and tissue distribution. To obtain data concerning metabolites production and accumulation in bile, two typical growth promoting treatments are carried out in cattle. In the first study, sixteen beef cattle were implanted with trenbolone acetate and estradiol. In the second one, three animals were implanted with zeranol and three were fed a diet containing zearalenone. Methods based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) were developed and validated to quantify the analytes of interest. The results evidenced that the biliary concentrations of the marker residues were always higher than those determined at the same time in urine and liver which are the matrices generally collected within the official monitoring programmes.