Effects on performance, tissue integrity, and metabolism of vitamin E supplementation for beef heifers fed a diet that contains gossypol

We conducted an experiment for 112 d with yearling beef heifers to evaluate the effects of cottonseed meal (CSM) fed with various concentrations of vi tamin E on hematological and tissue components. Heifers were assigned rando mly to four treatments, with eight heifers per treatment. The treatments co nsisted of the following dietary supplements: 1) CON, based on soybean meal with 30 IU vitamin E/kg; 2) GOS, based on CSM with 30 IU vitamin E/kg; 3) G+2E, based on CSM with 2,000 IU vitamin E.animal(-1).d(-1); and 4) G+4E, b ased on CSM with 4,000 IU vitamin E.animal(-1).d(-1). Supplements based on CSM provided 4.5 g of free and 50.5 g of total gossypol.animal(-1).d(-1). T he total gossypol present in the supplements was 29.1% of the negative isom er (-) and 70.9% of the positive isomer (+). Blood samples were collected a t the start of the experiment and every 2 wk thereafter up to 16 wk. There was a time x treatment interaction (P <.01) for plasma alpha-tocopherol (al pha-T) concentration; however, feeding gossypol did not decrease plasma alp ha-T. Weight gain, retinol palmitate, retinol, beta-carotene (P-C), hemoglo bin, and hematocrit were not affected by treatment. Erythrocyte osmotic fra gility (EOF) increased (P <.05) in gossypol-fed animals; however, vitamin E supplementation lowered EOF (P <.05). Heifers fed the supplements GOS, G+2 E, and G+4E had greater (P <.01) plasma (-)-, (+)-, and total gossypol than heifers fed CON from Collection 2 to the end of the experiment. There was a treatment effect (P <.05) on vitamin E and gossypol concentrations in dif ferent tissues, with no effect (P >.05) for trace minerals (Cu, Zn, Fe, and Se). Vitamin E concentration in tissue increased with increased dietary su pplementation of vitamin E. In heart and neck muscle, (-)-gossypol was grea ter(P <.05) than (+)-gossypol, but the reverse was true for liver. Gossypol decreased in vitro lipid peroxidation of liver homogenate in tissues. Goss ypol deposition in tissue was liver > heart > muscle. In summary, gossypol from CSM did not decrease concentrations of antioxidant vitamins, including alpha-T, vitamin A, and beta-C, or have any detrimental effect on performa nce of beef heifers.