Assessment of vitamin E nutritional status in yearling beef heifers

Effects of four dietary levels of DL-alpha-tocopheryl acetate (0, 500, 1,500, and 3,000 IU.animal-1.d-1) on serum, red blood cell (RBC), and tissue alpha-tocopherol concentrations were investigated in 32 yearling cattle during an 84-d trial. Supplemental vitamin E was fed for 28 d, withdrawn for 28 d, and then resumed for another 28 d. Blood was collected on d 1 before treatment administration, d 3, and biweekly thereafter. Serum alpha-tocopherol increased rapidly from pretreatment values (1.8 micrograms/mL) with linear (P < .05) treatment effects on d 3 and 14 and cubic treatment effects on d 28. Upon withdrawal of vitamin E supplementation, serum tocopherol concentrations declined and again increased rapidly and linearly by d 84 after supplementation was resumed. Concentration of alpha-tocopherol in RBC did not respond appreciably to supplemental vitamin E. There were no vitamin E treatment effects on blood lipid fractions (cholesterol and triglycerides). When serum tocopherol was expressed relative to the sum of cholesterol and triglycerides, response to vitamin E intake followed similar trends as serum alpha-tocopherol. The relationship between serum alpha-tocopherol concentrations or serum tocopherol:cholesterol plus triglycerides ratio and vitamin E intake was linear (P < .05) for d 14, 28, and 84 and linear with liver for d 84. Serum and liver tocopherol reflected vitamin E intake and can be used reliably to estimate vitamin E status in young cattle.