Abstract:
Alpha-tocopherol concentrations were measured in plasma, liver and adipose tissue of young sheep given dl-alpha-tocopherol acetate, orally or subcutaneously, at dosages of 0, 15, 30, 60 or 120 mg/kg liveweight while the sheep consumed a pelleted diet containing less than 10 mg/kg dry matter alpha-tocopherol. Significant responses in plasma alpha-tocopherol concentrations were observed after 1 and 4 days in sheep given oral doses of the vitamin but not in those given subcutaneous injections. Variation between animals within treatment groups was not reduced by expressing plasma alpha-tocopherol as a ratio of various plasma lipid fractions. Oral doses of 30 and 120 mg/kg liveweight of alpha-tocopherol increased the mean liver alpha-tocopherol concentrations at 7 days, but only the highest dose significantly increased liver concentrations above that of untreated sheep at 1 and 2 months. Increases in mean liver alpha-tocopherol concentrations were observed 1 month after subcutaneous injections, at dosages above 15 mg/kg liveweight, suggesting a slow mobilisation of the vitamin from the injection site. Concentrations of alpha-tocopherol in adipose tissue were not altered by alpha-tocopherol treatment. Plasma and liver alpha-tocopherol concentrations were positively correlated, although vitamin E treatments and time from treatment had small but significant effects on this relationship. The results suggest that oral dosage is preferable to subcutaneous injection when administering alpha-tocopherol acetate to sheep. An oral dose of 120 mg/kg liveweight will probably maintain adequate liver alpha-tocopherol concentrations for a period of about 2 months in sheep consuming diets of low vitamin E content.