EFFICACY OF DIETARY D-ALPHA-TOCOPHEROL AND DL-ALPHA-TOCOPHERYL ACETATE FOR WEANLING PIGS

A 2 x 3 factorial experiment in a randomized complete block design was conducted using a total of 180 weanling pigs in five replicates. The study evaluated the efficacy of two dietary vitamin E sources (D-alpha-tocopherol, DL-alpha-tocopheryl acetate) added at three dietary levels (16, 48, 96 IU/kg) during a 35-d postweaning trial. Pigs within each treatment were fed two similarly fortified vitamin E diets in sequence; the first contained 40% milk products and was fed to 14 d, and the second contained 20% milk product and 5% fat and was provided from 15 to 35 d postweaning. Five pigs per pen per replicate were bled weekly for serum analysis of alpha-tocopherol, Se, cholesterol, triglyceride, and glutathione peroxidase (GSH-Px) activity. At the end of the trial, one pig per pen was randomly selected and killed with liver, loin, lung, and heart excised and frozen for tocopherol analysis. Postweaning gains, feed intakes, and efficiencies were similar between the two vitamin E sources and at the various dietary levels. Serum tocopherol concentrations were consistently higher when D-alpha-tocopherol was provided. Vitamin E sources and levels had no effect nor did they influence weekly serum Se, cholesterol, or triglyceride concentrations or GSH-Px activity. A serum and tissue interaction (P < .05) response occurred between dietary vitamin E source x level with alpha-tocopherol concentrations increasing linearly (P < .01) as dietary vitamin E level increased, but at a higher rate when D-alpha-tocopherol than when DL-alpha-tocopheryl acetate as fed. These results indicate that dietary D-alpha-tocopherol may be more effectively absorbed and retained by weanling swine than DL-alpha-tocopheryl acetate. These data also suggest a biological activity of approximately 2.44 IU/mg of the alcohol relative to the acetate form of the vitamin for weanling swine.