Effect of anabolic steroids on reproductive function of young stallions.

Thirty-two stallions were used to determine the effect of anabolic steroids on reproductive function. Stallions were assigned to one of the four treatments: 1) .23 ml sesame oil/kg of body weight (BW; control, C); 2) 4.4 mg boldenone undecylenate/kg BW (4E); 3) 1.1 mg boldenone undecylenate/kg BW (1E) and 4) 1.1 mg nandrolone decanoate/kg BW (D). Injections were given at 3-wk intervals for 15 wk. Semen was collected every other day for 3 wk before the first injection and at the same frequency during d 85 through 105 (d 0 = day of first injection). Libido was assessed on the basis of reaction time. Total scrotal width was determined every 2 wk. Serum was obtained at various intervals and analyzed for concentrations of luteinizing hormone (LH). Portions of testicular parenchyma were used to determine spermatid reserves and to permit quantitative histological evaluation of spermatogenesis. Gel, gel-free and total seminal volumes and pH were not affected (P greater than .05) by steroid treatment. However, spermatozoal motility, spermatozoal concentration and total sperm/ejaculate were severely lowered (P less than .05) by all anabolic steroid treatments. Total scrotal width for stallions in the D, 4E and 1E groups was less (P less than .05) than that of C stallions by wk 5. The weight of the testes of the D, 4E and 1E stallions averaged only 40.1, 44.9 and 61.6%, respectively, of that for the controls. Spermatozoal production was altered, as evidenced by smaller (P less than .05) numbers of spermatids/testis and primary spermatocytes for all treated groups than for the controls. Anabolic steroid treatment had no effect (P greater than .05) on erection time, time to first mount, ejaculation time or number of mounts/ejaculation. treatment with anabolic steroids resulted in a depression in concentration of LH in all treatment groups.