Evaluation of steroid hormones anabolic use in cattle in Croatia

Natural sex hormones are part of the endocrine system and are found in animal biological material. On analysis of residual substances with anabolic effect and detection of their abuse, it is necessary to know the physiological levels of these hormones to be able to differentiate physiological concentrations from the illegal use of anabolics. The hormone concentrations exceeding the physiological ones, found on monitoring for illegal substance use, would point to the abuse of these substances for anabolic purpose. In the present study, concentrations of the natural hormones 17β-estradiol, progesterone and testosterone were determined in bovine plasma according to animal age and sex. Natural hormone concentrations were determined using quantitative validated ELISA methods in plasma samples from cattle of different breed composition collected at several farms in Croatia during the 2006-2009 period. Methods validation showed good mean recovery and repeatability (approx. 75-87%), demonstrating the methods efficiency in determination of 17β-estradiol, progesterone and testosterone level in cattle plasma, respectively. The level of sex hormones was statistically significantly higher in yearling plasma as compared with calf plasma (P<0.05). The highest levels of 17β-estradiol (0.03±0.01 ng/mL) and progesterone (4.87±1.63 ng/mL) were recorded in female yearlings, and of testosterone (9.44±5.47 ng/mL) in male yearlings. Results showed the steroid hormone levels to vary with animal age and sex, indicated that illegal use of anabolic substances could not be suspected in none of the study animals.