Combining two independent indirect methods as a new possibility for screening the illegal use of growth promotants

In this study the possibilities of combined indirect screening methods for the growth promotants clenbuterol and estradiol-17 beta benzoate and the combination of both these agents were investigated. Three groups of 5 male goat kids (two months of age) were treated for 4 weeks; clenbuterol per os, 10 micrograms/day/kg body weight via milkreplacer twice a day; 2 mg estradiol-17 beta benzoate weekly per i.m. injection; combined clenbuterol per os+estradiol-17 beta benzoate per injection. Five animals were not treated and served as controls. Nuclear Magnetic Resonance (NMR) was used as an initial tool to monitor the urine composition. The analysis of NMR spectra showed, that most treated animals had increased L-lactate/creatine ratios (L/C-ratio) in their urine, compared to control animals. For screening, L-lactate/creatine ratios could be determined directly in urine--in a simple, quick and inexpensive manner--by using enzymatic methods and an autoanalyzer. Histologically clenbuterol induced degenerative changes in the urethral and glandular epithelium of the prostate. Changes consisted of vacuolization of the epithelium and necrosis with nuclear pyknosis and fragmentation. Estradiol-17 beta benzoate induced metaplastic changes in the glandular tissue of the goat prostate. In combination with estradiol-17 beta benzoate, characteristics of both agents could be observed. The histological methods and observed effects can be used directly for screening. The combination of independent histological and L/C-ratio methods looks very promising with respect to screening of growth promotants. Since in both cases effects of growth promotants are detected, it may be expected that this approach is not limited to goats or clenbuterol and estradiol alone.