Reversibility of furazolidone-induced changes in testes and secondary sex characters of White Leghorn cockerels.

Furazolidone (Fz) was fed to 4 groups of cockerels 15 w of age at 0, 400, 800 and 1200 mg/kg feed for 3 w and then was withdrawn for another 3 w. In a second experiment conducted simultaneously cockerels were fed these same Fz levels for 6 w and then were withdrawn from Fz feed for 4 w. In both experiments, 800 and 1200 mg Fz/kg feed resulted in decreases in comb and wattle size and in the weight of testes. The testes had smaller seminiferous tubule diameters and increased relative and decreased absolute volumes of interstitium. Spermatogenesis was not observed in cockerels fed 800 and 1200 mg Fz/kg feed. Withdrawal of Fz resulted in increased comb and wattle size, weight of testes and diameter of the seminiferous tubules. There was also an increase in absolute volume of interstitium along with decreased relative interstitium volume. Spermatogenesis was restored.