title: Relative bioavailability of vitamin E in dairy cows following intraruminal administration of three different preparations of DL-alpha-tocopheryl acetate.
abstract: DL-alpha-tocopheryl acetate, a synthetic form of vitamin E, is routinely given as a dietary supplement to cattle. In this study we assessed the relative bioavailability of three formulations of DL-alpha-tocopheryl acetate in a kinetic study of plasma alpha-tocopherol in four Italian Friesian dairy cows, following intraruminal administration of a gelatin capsule containing 5,000 IU of DL-alpha-tocopheryl acetate. A Latin square design was used so that each animal received all formulations: (A) adsorbed on silica, (M) microencapsulated and (O) in oil form; 5,000 IU of DL-alpha-tocopheryl acetate was also administered intraperitoneally. The treatments were given following a 2-week period on a diet having no vitamin E supplementation with an interval of 8 days between each administration. Blood samples were collected at 0, 1, 10, 11, 21, 30, 48, 72, 96 and 168 h after each administration. The mean initial plasma alpha-tocopherol concentration (CO) was 2.38 +/- 0.57 micrograms/mL. Maximum plasma concentrations (Cmax) of alpha-tocopherol, adjusted for pretreatment values, were 3.90 +/- 0.13, 3.29 +/- 0.13 and 4.07 +/- 0.19 micrograms/mL, following administration of the A, M and O forms, respectively. The length of time required to obtain the maximum concentration (Tmax) in plasma was 57.5 +/- 7.8, 76.8 +/- 8.9 and 73.1 +/- 14.1 h, and the area under the curve (AUC) was 503.3 +/- 63, 620.25 +/- 108.5 and 465.4 +/- 38.7 micrograms.h/mL for A, M and O forms, respectively. Administration significantly increased the plasma alpha-tocopherol levels in all cases; however the A and M formulations had a lower elimination rate than the O form.
authors.affiliation: Istituto di Alimentazione Animale, Facoltà di Medicina Veterinaria, Milan, Italy. alivet@imiucca.csi.unimi.it
authors.forename: A
authors.initials: A
authors.lastname: Baldi
authors.forename: V
authors.initials: V
authors.lastname: Bontempo
authors.forename: F
authors.initials: F
authors.lastname: Cheli
authors.forename: S
authors.initials: S
authors.lastname: Carli
authors.forename: C
authors.initials: C
authors.lastname: Sgoifo Rossi
authors.forename: V
authors.initials: V
authors.lastname: Dell'Orto
mesh_terms: D000042:Absorption; D000818:Animals; D019540:Area Under Curve; D001682:Biological Availability; D002214:Capsules; D002404:Catheterization / Q000379:methods / Q000662:veterinary; D002417:Cattle / Q000097:blood / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods / Q000662:veterinary; D004032:Diet / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D004339:Drug Compounding / Q000662:veterinary; D005260:Female; D016014:Linear Models; D008892:Milk / Q000737:chemistry; D009821:Oils; D011355:Prodrugs / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D012417:Rumen / Q000378:metabolism*; D012822:Silicon Dioxide; D013997:Time Factors; D024505:Tocopherols; D014810:Vitamin E / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics; D024502:alpha-Tocopherol / Q000031:analogs & derivatives*
chemical_list: D002214:Capsules; D009821:Oils; D011355:Prodrugs; D014810:Vitamin E; D012822:Silicon Dioxide; D024502:alpha-Tocopherol; D024505:Tocopherols