Characterization of exogenous testosterone in livestock by gas chromatography/combustion/isotope ratio mass spectrometry: influence of feeding and age

✍ Scribed by Véronique Ferchaud; Bruno Le Bizec; Fabrice Monteau; François Andre

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 79 KB
• Volume: 14
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(20000430)14:8<652::aid-rcm928>3.0.co;2-c

✦ Synopsis

The detection of exogenous testosterone in bovine urine was investigated by using gas chromatography/ combustion/isotope ratio mass spectrometry (GC/C/IRMS). The carbon isotopic ratio measurement of epitestosterone, etiocholanolone (testosterone metabolite) and DHEA (testosterone precursor) in female bovine urines after testosterone enanthate administration was carried out. An important modification in the 13 C/ 12 C ratio of testosterone metabolites was observed, such that significant differences between precursor and metabolites of testosterone occurred until three weeks after intramuscular administration of testosterone enanthate. The factors influencing the 13 C/ 12 C of endogenous steroids were studied especially through cattle feeding and age. The DHEA mean d 13 C value was found to vary between À25 and À26% when hay and concentrate diet were used for fattening. On the other hand the d 13 C value observed when maize silage was used increased to À20%. Testosterone metabolites showed the same d 13 C increase as their precursor. Moreover, we observed a clear relationship between age and efficiency of misuse determination. Indeed, because of the lower concentration of natural hormones in young animals, the contribution of exogenous molecules increases significantly compared with older subjects. Consequently, demonstration of administration is easier to achieve in calves than in mature animals.