Study of the metabolism of testosterone, nandrolone and estradiol in cattle

The current metabolism study was undertaken to identify key analytes in uri ne, plasma and bile following testosterone, nandrolone and estradiol admini strations to cull cows, heifers and steers. This information will be used t o develop confirmatory analysis procedures. In the present study, mixtures (1:1) of testosterone, nandrolone or estradiol and their deuterium labelled analogues were administered to cull cows, heifers and steers. Two analogue s of deuterium labelled testosterone were synthesised and administered, to facilitate identification of metabolites. Following administration, urine, plasma and bile samples were collected and subjected to solid phase extract ion. The extracts were derivatised and analysed by CC-MS. The major analyte s derived from the administered steroids were identified on the basis of th e twin ion peaks produced for their non-labelled and deuterium labelled ana logues and their stereochemistries determined by comparison of retention ti mes with appropriate reference standards. Using suitable internal markers, excretion profiles for the major analytes in urine and plasma have been det ermined and levels in isolated bile samples estimated. This work is on-goin g, and this paper is a summary of some of the studies completed to date.