Detection of endogenous steroid abuse in cattle: results from population studies in the UK.

The use of steroids as growth-promoting agents in food production is banned under European Union legislation. Detecting the abuse of testosterone, nandrolone, boldenone, oestradiol and progesterone is complicated by the fact that these steroids are known to be endogenous in certain situations. In this study, the concentrations of characteristic metabolites of each of these steroids were quantified in populations of untreated steers and heifers. Steroid concentration population data were then used by a statistical model (the Chebyshev inequality) to produce threshold concentrations for screening and confirming the abuse of these steroids in steer and non-pregnant heifer urine. In addition to thresholds based on testing one animal (a '1 out of 1' approach), new methods based on testing multiple animals from a herd (a 'y out of n' approach) allowed threshold concentrations to be significantly reduced and hence false compliances to be minimised. In the majority of cases, the suggested thresholds were found to be capable of confirming the abuse of endogenous steroids in steers and heifers. In the case of oestradiol abuse in the female, however, confirmation based on a threshold is not possible and alternative methods such as gas chromatography-combustion-isotope ratio mass spectrometry are required. In addition to the steer and heifer populations, a small number of pregnant animals were also tested, yielding insights into the biosynthetic pathways of some of the steroids.