LONG-TERM EFFECTS OF GOSSYPOL AND VITAMIN-E IN THE DIETS OF DAIRY BULLS

Long-term effects of the inclusion of cottonseed meal in the diet on h ematological and tissue parameters of Holstein bulls were investigated . Twenty-four Holstein bulls that were approximately 6 mo of age recei ved the following treatments for 10 mo: 1) soybean meal plus 30 IU of vitamin E/kg, 2) cottonseed meal plus 30 IU of vitamin E/kg, and 3) co ttonseed meal plus 4000 IU of vitamin E/d per bull. Treatments 2 and 3 were formulated to supply 14 mg of free gossypol/kg of body weight pe r d. Average daily gain, total gain, and final body weights were not a ffected by treatment. The osmotic fragility of erythrocytes was greate r during all collection periods for bulls on treatments 2 and 3 than f or bulls on treatment 1. The inclusion of 4000 IU of vitamin E/d per b ull did not reduce the increase in the osmotic fragility of erythrocyt es that was caused by gossypol. Bulls on treatment 3 had higher plasma a-tocopherol concentrations than did bulls on treatments 1 and 2. Vit amin E supplementation did not affect gossypol concentrations in plasm a or tissue. The highest gossypol concentrations were found in the liv er followed by the heart and testis. In vitro lipid peroxidation of ti ssue indicated that gossypol acts as an antioxidant in lipid peroxidat ion systems, and its role as an antioxidant may be dependent on dose o r tissue. Cottonseed meal in the diets of bulls did not affect growth or vitamin E status.