Long-term effects of feeding gossypol and vitamin E to dairy calves

Male Holstein calves were used to test the effect of feeding 400 mg of free gossypol/kg of diet and to determine whether vitamin E could counteract go ssypol toxicity. Fifty-two calves were allotted to treatments as follows: 1 ) soybean meal-based starter; 2) cottonseed meal-based starter; 3) cottonse ed meal-based starter + 2000 IU of vitamin E/d per calf, and 4) cottonseed meal-based starter + 4000 IU of vitamin E/d per calf. Vitamin E supplementa tion (treatments 3 and 4) improved weight gain and feed intake over calves on treatment 1. Gossypol concentrations in plasma were higher in calves on treatments 2, 3, and 4 than in calves on treatment 1; however, no differenc es were observed among animals receiving the three cottonseed meal diets. H emoglobin and hematocrit were decreased in calves receiving treatment 2, an d vitamin E supplementation counteracted this effect (treatments 3 and 4). Plasma a-tocopherol concentrations were not affected by gossypol intake and followed the vitamin E supplementation pattern. During the experimental pe riod, 10 calves died, six from treatment 2 and two each from treatments 3 a nd 4. Necropsy findings from 4 of 10 calves were suggestive of gossypol tox icity. Histopathological examination revealed centrilobular necrosis in the liver and atrophy and vacuolation of cardiocytes. Feeding cottonseed meal caused death of some calves with gossypol related toxicity signs, but did n ot decrease plasma alpha-tocopherol; however, vitamin E supplementation inc reased performance and may have conferred some protection against gossypol toxicity.