Serum alpha-tocopherol concentration in sheep after intramuscular injection of DL-alpha-tocopherol

Forty-three crossbred wethers weighing 35 to 60 kg were used to investigate the effect of a single i.m. injection of DL-alpha-tocopherol (DL-alpha-ol). Animals were offered 1 kg/d of a basal diet containing 25 ppm of vitamin E. Lambs were randomly assigned to one of five DL-alpha-ol injection treatments as follows: 1) control (placebo, 0 IU), 2) 125 IU, 3) 250 IU, 4) 500 IU, or 5) 1,000 IU. Blood samples were taken via jugular venipuncture on d 1 before treatment administration and thereafter at designated intervals up to 360 h postinjection. The i.m. injections of DL-alpha-ol irrespective of dose increased serum alpha-tocopherol. Results showed a dose x time interaction (P less than .0001) across all treatments. Serum alpha-tocopherol increased rapidly to maximum concentration during the first 8 to 12 h for all non-zero treatments, followed by a rapid decline to pretreatment values. The mean serum alpha-tocopherol concentration at 0 h was .69 microgram/mL. Estimated peak serum alpha-tocopherol concentrations +/- SE were 6.68 +/- 1.04, 9.62 +/- 1.04, 21.66 +/- 2.37, and 50.75 +/- 7.05 micrograms/mL for Treatments 2 through 5, respectively. Results showed a quadratic dose effect (P less than .0003) on maximum response with apparently no effect on time taken to reach this peak. There was also a quadratic dose effect (P less than .0001) on the area under the concentration-time curve. The time taken for serum alpha-tocopherol to return to pretreatment levels increased with dose (56, 64, 67, and 74 h, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)