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 r eceive 0, 150, 250 or 350 mg Fz/kg feed daily for 5-w. Blood samples w ere taken at weekly intervals. The birds were challenged with 500 IU h uman chorionic gonadotropin (hCG) iv at the age of 24 w before slaught ering. Concentration of testosterone in the plasma was measured by a s pecific radioimmunoassay. Testicular tissue was process-ed for morphom etric studies. Testicular weights of the groups fed 250 or 350 mg Fz/k g feed/d were decreased (P<0.05). Plasma testosterone levels were affe cted by age (P<0.001) and dose of Fz (P<0.001). Mean plasma testostero ne levels during and after drug administration were reduced (P<0.05) b y all Fz doses. Human chorionic gonadotropin administration led to poo r testosterone response (P<0.05) in all Fz-dosed groups, but not the c ontrol group (P<0.05). As compared to the control, Fz-dosing reduced t he seminiferous tubule diameter (P<0.05) at the 350 mg/kg feed dose, s eminiferous epithelial height (P<0.05) at the 250 and 350 mg/kg feed d oses, 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 testic ular level.