Blood plasma and tissue concentrations of vitamin E in beef cattle as influenced by supplementation of various tocopherol compounds.

Twenty-four crossbred beef cows were used to investigate the concentration of alpha-tocopherol in plasma and tissues following oral administration of four tocopherol sources. Animals were allotted to the following treatments: DL-alpha-tocopherol, D-alpha-tocopherol, DL-tocopheryl acetate and D-alpha-tocopheryl acetate. Animals received a daily oral dose of 1,000 IU of the respective tocopherol treatment for 28 d and then were slaughtered. Blood samples were collected on d 0, 1, 7, 14 and 28 for tocopherol concentration assays, and samples from 10 different tissues were collected from slaughtered cows. Identification of alpha-tocopherol in tissues was confirmed by HPLC retention times and by comparison of mass spectra with that of alpha-tocopherol standards. The D-alpha-tocopherol and its acetate ester increased plasma tocopherol concentration faster than the racemic products, the greatest response occurring with D-alpha-tocopherol. Across all treatments, the highest alpha-tocopherol concentrations were noted in the adrenal gland and liver, the lowest in muscle and thyroid tissue. Tissue analyses confirmed that in adrenal gland, kidney, liver and lung, alpha-tocopherol concentrations were higher following D-alpha than DL-alpha-tocopherol supplementation.