Effect of feeding gossypol in cottonseed meal on growth, semen quality, and spermatogenesis of yearling Holstein bulls

Yearling Holstein bulls were fed a corn silage ration supplemented with either cottonseed meal with gossypol or soybean meal in two trials to evaluate the effect of feeding gossypol on reproductive characteristics. In Trial 1, roughage to concentrate ratio was 88:12 and was fed for 60 d. In Trial 2, roughage to concentrate ratio was 50:50 and was fed for 42 d. Cottonseed meal concentrate had 3.03 g total gossypol/kg DM. Cottonseed meal concentrate was fed to provide 6 and 30 mg total gossypol/kg BW per d in Trials 1 and 2. Ejaculates were collected twice weekly via artificial vagina and critiqued for quantity and quality before and after thawing and after postthaw incubation. Leptotene spermatocytes to Sertoli cell ratio in stage 1 tubules was used to evaluate spermatogenesis. Growth characteristics and tissue total gossypol concentrations were also evaluated. No gossypol was found in plasma taken before, during, or after Trial 1 or from body organs or plasma taken during or after Trial 2. No signs of gossypol toxicity were observed, and growth characteristics were similar on both rations. Gossypol in cottonseed meal fed at low to moderate concentrations was not deleterious to seminal quantity or quality, and spermatogenesis was unaffected by treatment.