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The specific function of α-tocopherol is to protect the long-chain PUFA and thus maintain their concentrations for important events, such as membrane fluidity and eicosanoid signaling. The present study evaluated the effect of increasing supplementation of all-rac- α-tocopheryl acetate and dietary fatty acid composition during a four week period after weaning on porcine tissue composition of α-tocopherol stereoisomers and fatty acids, and on hepatic expression of genes involved in transfer of α-tocopherol, and oxidation and metabolism of fatty acids. Nine pigs of each litter were allotted to nine dietary treatments in a 3×3 factorial arrangement of treatments in a randomized complete block design. Pigs were obtained from sows which had been provided a lactation feed containing a high content of vitamin E (250 mg all-rac-α-tocopheryl acetate/kg feed), and during the last 2 weeks of the suckling period, piglets received creep feed containing 70 mg all-rac-α-tocopheryl acetate/kg feed. From day 28 to 56 of age, pigs were provided 5% of tallow, fish oil or sunflower oil and 85, 150, or 300 mg/kg of all-rac-α-tocopheryl acetate. Samples of liver, heart, and adipose tissue were obtained from littermates at day 56.
Tissue fatty acid composition was highly influenced by dietary fat sources. Dietary fatty acid composition (P<0.001) and vitamin E supplementation (P<0.001) influenced the α-tocopherol stereoisomer composition in liver, i.e. less proportion of the RRR- α-tocopherol was observed in pigs provided fish oil and the highest dose of vitamin E in comparison with other dietary treatments. In addition, the stereoisomer composition of α-tocopherol in heart, and adipose tissue was influenced by dietary treatments. Expression of genes in liver involved in the regulation of FA conversion, SCD (stearoyl-CoA-desaturase) (P=0.002) and D6D (∆6-desaturase) (P=0.04) were lower in pigs fed fish oil compared to other treatments, whereas the fatty acid oxidation, as indicated by the expression of PPAR-α, was higher when sunflower and fish oil was provided (P=0.03). It is concluded that dietary fatty acid composition rather than vitamin E supplementation affects the composition of fatty acids in liver, heart and adipose tissue, and the expression of hepatic lipogenic genes.
C Lauridsen, P K. Theil and S K. Jensen. (2013) Composition of α-tocopherol and fatty acids in porcine tissues after dietary supplementation with vitamin E and different fat sources. Animal Feed Science and Technology 179;93– 102. doi:10.1016/j.anifeedsci.2012.10.007