Effect of vitamin E source, natural versus synthetic, and quantity on serum and tissue alpha-tocopherol concentrations in finishing swine.

Relative vitamin E status of pigs fed natural or synthetic vitamin E was evaluated based on serum and tissue alpha-tocopherol concentrations. Individually fed finishing gilts at a BW of 70.5 kg (n = 24) were allotted to dietary treatments based on initial BW. The 5 dietary treatments consisted of a positive control diet using synthetic vitamin E acetate (Syn E Ac) supplemented at 22 mg/kg, and 4 dietary levels of natural vitamin E acetate (Nat E Ac) supplemented at 6.71, 8.33, 11.00, and 16.18 mg/kg of diet. Before initiation of the 32-d experiment, pigs were fed a non-vitamin E-fortified diet for 30 d. Diets were formulated to contain true ileal digestible lysine of 0.9 and 0.8% for the pretest and test diets. Serum samples were collected on d 15 and 32, whereas tissue samples were collected on d 32 for alpha-tocopherol analysis. Serum alpha-tocopherol concentrations on d 15 and 32 were greater (P < 0.05) in pigs fed 8.33, 11.00, or 16.18 mg/kg of Nat E Ac than in pigs fed 22 mg/kg of Syn E Ac. When compared with pigs fed 22 mg/kg of Syn E Ac, alpha-tocopherol concentrations were greater (P < 0.05) in 6 tissues (heart, kidney, spleen, liver, lung, and adipose) in pigs fed 16.18 mg/kg of Nat E Ac; greater (P < 0.05) in heart, kidney, spleen, liver, and adipose tissue in pigs fed 11.00 mg/kg of Nat E Ac; and greater (P < 0.05) in spleen, loin, and adipose tissue in pigs fed 8.33 mg/kg of Nat E Ac. As dietary Nat E Ac increased from 6.71 to 16.18 mg/kg, serum alpha-tocopherol increased linearly (P < 0.01) on d 15 and 32 of the experiment. Increasing dietary Nat E Ac linearly increased (P < 0.05) alpha-tocopherol concentrations for lung, heart, kidney, spleen, and liver. These results indicate that Nat E Ac was an effective vitamin E source and its relative bioavailability was substantially greater than 1.36 for finishing swine when compared with Syn E Ac.