BIOAVAILABILITY OF VITAMIN-E COMPOUNDS IN LAMBS

A study was carried out to assess the bioavailabilities of several forms of vitamin E in lambs. A total of 40 lambs was allotted to eight dietary groups of five each and supplemented or not daily for 60 d with equimolar amounts of different vitamin E compounds as follows: 1) control, no supplemental vitamin E, 2) DL-alpha-tocopheryl acetate, 3) D-alpha-tocopheryl acetate, 4), D-alpha-tocopheryl succinate, 5) D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS), 6) DL-alpha-tocopheryl nicotinate, 7) DL-alpha-tocopheryl nicotinate + TPGS, or 8) D-alpha-tocopheryl acetate + TPGS. During these 60 d, serum alpha-tocopherol concentrations in the control lambs remained constant and lower (P < .05) than in lambs that received all treatments. Various indices of bioavailability, including C(mas) - C(i) (concentration maximum - concentration initial), C(t) - C(i) (concentration terminal - concentration initial), areas under the serum concentrations profiles, and pooled increment were higher (P < .05) with D-alpha-tocopheryl acetate + TPGS than in the other groups, suggesting a synergism between these forms. No such effect was observed between nicotinate and TPGS. For the TPGS, a water-soluble form of vitamin E, the indices of bioavailability were lower (P < .05) than for the other groups. D-alpha-tocopheryl acetate resulted in a bioavailability that outranked all the other forms of vitamin E, except those of D-alpha-tocopheryl acetate + TPGS. A slightly higher bioavailability index was observed for D-alpha-tocopheryl succinate than for DL-alpha-tocopheryl nicotinate. Dosing daily with 300 mg of various vitamin E compounds in lambs resulted in significant differences in serum alpha-tocopherol concentrations.