An evaluation of natural (RRR-α-tocopheryl acetate) and synthetic (all-rac-α-tocopheryl acetate) vitamin E fortification in the diet or drinking water of weanling pigs

Three experiments conducted with weanling pigs evaluated the effects of vitamin E added to the drinking water or diet on plasma and tissue alpha-tocopherol concentrations. When natural or synthetic vitamin E was used, it was added at an IU-equivalent basis, but natural vitamin E was 73.5% (mg basis) of the synthetic vitamin E. Experiment 1 used 18-d-old weanling pigs (n = 120) in a 3 x 2 factorial arrangement of treatments in a randomized complete block design with 4 replicates. The first factor evaluated the dietary levels of natural vitamin E (RRR-alpha-tocopheryl acetate) added at 0, 50, or 300 IU/kg, whereas the second factor was the natural vitamin E added to the drinking water at 0 or 100 IU/L. Pigs were bled at periodic intervals, and 1 pig per pen was killed at the end of the 21-d trial and tissues ( liver, heart, lung, and loin) were collected for alpha-tocopherol analysis. When vitamin E was not added to the diet or water, plasma alpha-tocopherol declined over the 21-d period. Although there were some interactions (P < 0.01), tissue and plasma alpha-tocopherol concentrations increased linearly when vitamin E was added to the diet or water. Experiment 2 was a 3 x 2 factorial in a randomized complete block design with 4 replicates. A total of 96 pigs weaned at 18 d of age, with an initial BW of 6.2 kg, were fed a nonvitamin E fortified diet, but natural or synthetic (all-rac-alpha-tocopheryl acetate) vitamin E was added to their drinking water at 50, 100, or 150 IU/L. Pigs were bled at 0, 3, 7, 10, 14, and 21 d postweaning, with tissues (liver, lung, heart, and loin) collected for alpha-tocopherol analysis at d 21. The results indicated that plasma alpha-tocopherol concentrations increased (P < 0.01) as vitamin E increased, with greater tissue alpha-tocopherol concentrations (P < 0.01) when natural vitamin E was provided. Experiment 3 was conducted in 2 replicates, but pigs (n = 60) were not provided vitamin E in the diet or water for 7 d postweaning, and then natural or synthetic vitamin E was added to the drinking water as in Exp. 2 (50, 100, or 150 IU/L). Pigs were bled at 0, 2, 4, 6, 8, 10, and 24 h after being provided vitamin E to evaluate the absorption from each vitamin E source and level. Plasma alpha-tocopherol increased quadratically (P < 0.01) and plateaued at 8 to 10 h for each treatment group. These results indicate that adding vitamin E to the pig's water supply at weaning was more effective in increasing plasma alpha-tocopherol than when it was added to the diet during the initial 14 d postweaning, and that natural vitamin E was a superior source compared with synthetic vitamin E.