BIOAVAILABILITY OF VARIOUS VITAMIN-E COMPOUNDS FOR FINISHING SWINE

Relative bioavailabilities of four chemical forms of vitamin E were ev aluated when supplemented in diets of finishing swine for 28 d. Forty crossbred pigs (80 kg), individually penned, were divided equally amon g five treatments. Treatments consisted of corn soybean meal-based die ts supplemented with DL-alpha-tocopherol, DL-alpha-tocopheryl acetate, D-alpha-tocopherol, or D-alpha-tocopheryl acetate. A treatment withou t vitamin E supplementation (negative control) served as the fifth tre atment. Each compound was supplemented at 62 IU/kg of diet. Blood samp les were collected on d 0, 1, 2, 7, 14, 21, and 28. On d 29, half the pigs were slaughtered to obtain tissue samples. Feed samples, taken fr om feeders, were also collected on d 0, 5, 14, and 21. All vitamin E f orms fed increased (P < .01) serum (alpha-tocopherol by d 2 and peaked by d 7. Serum alpha-tocopherol in pigs fed either acetate form remain ed elevated beyond d 7; serum alpha-tocopherol steadily declined and w as lower (P < .01) on d 14, 21, and 28 in pigs fed either alcohol form compared with concentrations in the acetate-fed pigs. The decrease wa s probably a reflection of poor stability of the alcohol forms observe d in the feed; the acetate forms were found to be stable in the feed o ver the 28-d study. Dietary supplementation of D-alpha-tocopheryl acet ate resulted in the highest serum alpha-tocopherol throughout the stud y. A similar trend was observed in tissue (liver, backfat, leaf fat, s emimembranosus, rhomboideus) alpha-tocopherol and serum: the liver had the highest concentration. The bioavailability of D-alpha-tocopheryl acetate for swine seems to be greater than that predicted from traditi onal bioassays with the rat.