Furazolidone treatment suppresses pubertal testosterone secretion in male broiler breeder birds (Gallus domesticus).

We determined the effect of chronic administration of furazolidone (Fz) on sexual maturation of male broiler breeder birds (Ross 308; Gallus domesticus). A total of 20 15-w-old birds were randomly assigned to receive 0, 150, 250 or 350 mg Fz/kg feed daily for 5-w. Blood samples were taken at weekly intervals. The birds were challenged with 500 IU human chorionic gonadotropin (hCG) i.v. at the age of 24 w before slaughtering. Concentration of testosterone in the plasma was measured by a specific radioimmunoassay. Testicular tissue was processed for morphometric studies. Testicular weights of the groups fed 250 or 350 mg Fz/kg feed/d were decreased (P < 0.05). Plasma testosterone levels were affected by age (P < 0.001) and dose of Fz (P < 0.001). Mean plasma testosterone levels during and after drug administration were reduced (P < 0.05) by all Fz doses. Human chorionic gonadotropin administration led to poor testosterone response (P < 0.05) in all Fz-dosed groups, but not the control group (P < 0.05). As compared to the control, Fz-dosing reduced the seminiferous tubule diameter (P < 0.05) at the 350 mg/kg feed dose, seminiferous epithelial height (P < 0.05) at the 250 and 350 mg/kg feed doses, and Leydig cell nuclear diameter (P < 0.05) at the 350 mg/kg feed dose. This data suggest that sexual maturation in male broiler breeder birds is adversely affected by chronic Fz-administration. Actions of Fz on sexual maturation probably involve a direct effect at the testicular level.