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Different studies has been reported that the relative bioavailability of natural vitamin E acetate (Nat E Ac) to syntetic E acetate (Syn E Ac) is underestimated in young and adult swine when using the commonly accepted ratio of 1.36:1. On the other hand the relative bioavailability of Nat E Ac to Syn E Ac has been estimated to be approximately 2:1 in sows. Therefore the objective of the present study was to determine the retention of α-tocopherol in blood and various body tissues of finishing swine fed diets containing various levels of Nat E Ac as compared with a positive control diet containing Syn E Ac.
Relative vitamin E status of pigs fed natural or synthetic vitamin E was evaluated based on serum and tissue α-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 Syn E Ac supplemented at 22 mg/kg, and 4 dietary levels of 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 pre-test and test diets. Serum samples were collected on d 15 and 32, whereas tissue samples were collected on d 32 for α-tocopherol analysis.
Serum α-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, α-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 α-tocopherol increased linearly (P < 0.01) on d 15 and 32 of the experiment. Increasing dietary Nat E Ac linearly increased (P < 0.05) α-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.
H Yang, DC Mahan, DA Hill, TE Shipp, TR Radke and MJ Cecava. Effect of vitamin E source, natural versus synthetic, and quantity on serum and tissue alpha-tocopherol concentrations in finishing swine. 2009. Journal of Animal Science, 87:4057-4063. doi:10.2527/jas.2008-1570