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

The residue profiles of 17α-/17β-boldenone conjugated (17α/β-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 4h after feeding and further from all the animals. Detectable amounts of 17α-Bol conjugated were measured in urine collected from all calves, but the concentrations of 17α-Bol were higher in urine from calves receiving the milk replacer with the greater amount of phytosterols. During the whole experiment, 17β-Bol and ADD were never detected in urine samples collected.