Excretion profile of boldenone in urine of veal calves fed two different milk replacers

The residue profiles of 17alfa-/17beta-boldenone conjugated (17a/b-Bol) and ADD were investigated by liquid chromatography–tandem mass spectrometry (LC–MS/MS) in urine of male veal calves fed two commercial milk replacers, with different content of cholesterol and phytosterols. The urine samples were collected within 4 h after feeding and further from all the animals. Detectable amounts of 17a-Bol conjugated were measured in urine collected from all calves, but the concentrations of 17a-Bol were higher in urine from calves receiving the milk replacer with the greater amount of phytosterols. During the whole experiment, 17b-Bol and ADD were never detected in urine samples collected.