EFFECT OF 19-NORANDROSTENOLOLYLAURATE ON SEMEN CHARACTERISTICS OF COLTS

The long-term effects of the anabolic steroid 19-norandrostenololylaur ate on semen characteristics of Finnhorse colts were studied in 3 expe riments. Semen was collected initially at 24 months of age and then tw ice a year. In experiment I, 500 mg or 100 mg of steroid per animal wa s given every 3rd week from 12 or 16 months to 24 months of age. In co lts treated with 500 mg of anabolic steroid every 3rd week, azoospermi a was observed in 3 out of 5 colts in the first semen collections, imm ediately after the end of treatment. The other 2 colts had low sperm n umbers and a high percentage of proximal droplets in relation to contr ol animals. The 100 mg group was less affected by steroid treatment th an the 500 mg group. The seminal changes were observed to be reversibl e. All of the colts had spermatozoa in their ejaculates 4 months after the end of treatment. Two years after cessation of treatment, sperm n umbers in treated animals exceeded those in the control group. In expe riment II, colts were treated from 7 months to 12 months of age with a dose of 1 mg/kg every 3rd week or 0.3 mg/kg every week. The first sem en collections took place 12 months after the last treatment. The anim als treated with 0.3 mg/kg every week were less affected than those tr eated with 1 mg/kg every 3rd week. In experiment III, animals were tre ated from 3 months to 8 months of age, and the interval from the last treatment to the first semen collection was 16 months. There were no s ignificant differences between the groups in any of the semen paramete rs examined In the last semen collection, the control animals had nume rically higher spermatozoal concentration and progressive motility and less dead sperm than the treated animals. It was concluded that the a dverse effects of steroid treatment on semen characteristics were reve rsible, at least in the groups treated at age 7-25 months.