Suppression of androstenone in entire male pigs by anabolic preparations

At an age of 19 weeks and an average weight of 80.5 kg, four boars each wer e implanted i.m. with two doses of either Synovex-H(R) (SH; total dose 400 mg testosterone propionate + 40 mg oestradiol benzoate) or Synovex Plus(R) (SP; total dose 400 mg trenbolone acetate + 56 mg oestradiol benzoate), res pectively. A third group of four boars served as control. The animals were slaughtered 5 weeks after implantation and the testes weights recorded. Hor mone (androgen and oestradiol benzoate) residues in implantation sites were quantified by high-performance liquid chromatography with UV detection, an d the boar taint steroid androstenone was determined in fat by enzyme-immun oassay (EIA). Gas chromatography-mass spectrometry analysis additionally co nfirmed the identity. Plasma testosterone and trenbolone concentrations wer e measured by EIA. Plasma testosterone and fat androstenone concentrations were reduced to basal levels by the SP treatment. With SH the decrease in f at androstenone concentrations was inconsistent between animals. Androgen a nd estrogen residues in implantation sites were higher in SH boars than in SP boars (179 mg + 19 mg versus 85 mg + 15 mg, respectively). Besides the r esulting higher resorbed doses, the higher SP efficiency was attributed to greater hypothalamic negative feedback activity of trenbolone compared with testosterone. Including the implantation site, whole batches of processed meat products would be contaminated above the international threshold level s for these hormones in meat. (C) 2001 Elsevier Science B.V. All rights res erved.