Survey of the hormones used in cattle fattening based on the analysis of Belgian injection sites.

Although the illegal use of orally administered compounds in cattle fattening has gained popularity, injection sites are still frequently found during control experiments on the carcasses in the slaughterhouses. The high concentrations of hormones in injection sites enable screening for the presence of 39 different hormones by a simple extraction followed by a fast and simple high-performance thin-layer chromatography analysis. Analysis of injection-site tissue is particularly successful for determining the hormones that are illegally injected. This data can not be obtained by analysis of other biological matrices like faeces, kidney fat or urine, owing to metabolization and selective excretion and/or deposition of these compounds. Since 1989, over 2000 injection sites have been analysed in our laboratory, which yielded a good survey of the hormones that were illegally injected. Over this period, the natural hormones estradiol and testosterone (mostly present as their esters) have obviously been used extensively. It is clear that since 1990 clostebol acetate has remained the most abused exogenous hormone. Additionally, some distinct trends were noticed, e.g., a tendency towards a highly decreased use of nandrolone, an increased use of progesterone and an increased occurrence of certain androgens like stanozolol and fluoxymesterone.