American Journal of Clinical Nutrition, Vol 21, 135-142, Copyright © 1968 by The American Society for Clinical Nutrition, Inc.

Alpha-Tocopherol Requirements for Equine Erythrocyte Stability

¹ From the Department of Veterinary Science, University of Kentucky, Lexington, Kentucky

Foals were tocopherol depleted by feeding a pelleted semipurified ration containing Torula yeast, cornstarch, alpha-cellulose, ground limestone, trace mineral salt, MgO, and vitamins A and D₂. The layering hemolysis (LH) test was used to estimate the alpha-tocopherol requirements for equine erythrocyte stability. The layering hemolysis was coincident with serum tocopherol levels below 1.15 µg/ml and occurred approximately 200 days after tocopherol depletion began.

In tocopherol repletion-depletion studies an average of 27 µg of parenteral or 233 µg oral alpha-tocopherol/kg body wt per day was required for maintenance of equine RBC stability (prevention of LH). Tocopherol-deficient erythrocytes in peripheral blood were protected from LH between 4 and 5 hr postparenteral tocopherol administration. The addition of 1 and 10 µg alpha-tocopherol/ml of 0.8% saline containing 10 and 20 mm³, respectively, of severely tocopherol-deficient blood per milliliter saline was required to prevent LH in vitro. For the same two concentrations of moderately tocopherol-deficient whole blood in 0.8% saline, 0.1 and 1 µg alpha-tocopherol/ml saline, respectively, were required to prevent LH in vitro. The average alpha-tocopherol requirement per million equine erythrocytes was estimated at 7.96 mµg.