Supplementary alpha-tocopherol acetate in full-fat rapeseed-based diets for pigs: influence on tissue alpha-tocopherol content, fatty acid profiles and lipid oxidation

Twenty-four Large White x Landrace pigs were individually fed, from 50 to 9 0 kg live weight, either a control (CONT) diet containing palm oil or one o f three diets based on full-fat rapeseed (250 g kg(-1)) (diets RD), The RD diets were supplemented with 0, 200 or 500 mg alpha-tocopherol acetate (ATA ) kg(-1) diet (diets RD0, RD200 and RD500 respectively). Diets were formula ted to be isonitrogenous and isocaloric. Fatty acid profiles and alpha-toco pherol (AT) content of subcutaneous fat (SCF), M longissimus dorsi (L dorsi ) and M semimembranosus (S memb) were measured. Lipid oxidation was measure d in samples of L dorsi stored at 4 degrees C for up to 8 days and followin g induction with ferrous sulphate in muscle homogenates. Tissue fatty acid profiles were influenced by dietary fatty acid composition. When samples fr om pigs fed RD diets were compared with CONT, they had significantly higher levels of unsaturated fatty acids and n-3 polyunsaturated fatty acids (PUF A) and higher ratios of PUFA/saturated fatty acids. RD diets reduced the me lting point of lipid from SCF by about 4 degrees C, Dietary ATA supplementa tion did not influence tissue fatty acid composition and the melting point of lipid in SCF. Tissue AT concentration increased with increasing dietary levels of ATA, Supplementation of the RD diets with ATA significantly impro ved the oxidative stability of lipids in L dorsi during refrigerated storag e (4 degrees C) and in iron-induced lipid peroxidation. There was no additi onal benefit of increasing ATA supplementation from 200 to 500 mg kg(-1) di et in terms of preventing lipid oxidation. (C) 2000 Society of Chemical Ind ustry.