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

Abstract

Twenty-four Large White x Landrace pigs were individually fed, from 50 to 90 kg live weight, either a control (CONT) diet containing palm oil or one of three diets based on full-fat rapeseed (250g kg -1 ) (diets RD). The RD diets were supplemented with 0, 200 or 500mg α-tocopherol acetate (ATA) kg -1 diet (diets RD0, RD200 and RD500 respectively). Diets were formulated to be isonitrogenous and isocaloric. Fatty acid profiles and α-tocopherol (AT) content of subcutaneous fat (SCF), M longissimus dorsi (L dorsi) and M semimembranosus (S memb) were measured. Lipid oxidation was measured in samples of L dorsi stored at 4°C for up to 8 days and following induction with ferrous sulphate in muscle homogenates. Tissue fatty acid profiles were influenced by dietary fatty acid composition. When samples from pigs fed RD diets were compared with CONT, they had significantly higher levels of unsaturated fatty acids and n-3 polyunsaturated fatty acids (PUFA) and higher ratios of PUFA/saturated fatty acids. RD diets reduced the melting point of lipid from SCF by about 4°C. Dietary ATA supplementation 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 improved the oxidative stability of lipids in L dorsi during refrigerated storage (4°C) and in iron-induced lipid peroxidation. There was no additional benefit of increasing ATA supplementation from 200 to 500mg kg -1 diet in terms of preventing lipid oxidation.