Supplementary alpha-tocopherol acetate in full-fat rapeseed-based diets for pigs: effects on the alpha-tocopherol content and fatty acid composition of pig muscle microsomal and mitochondrial membranes and membrane lipid peroxidation

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 (FFR; 250 g kg(-1)) (diets RD), Th e RD diets were supplemented with 0, 200 or 500 mg DL-alpha-tocopherol acet ate (ATA) kg(-1) diet (diets RD0, RD200 and RD500 respectively). Diets were formulated to be isonitrogenous and isocaloric. M semimembranosus (S memb) muscle subcellular fractions (microsomes and mitochondria) were analysed f or fatty acid composition, alpha-tocopherol (AT) content and oxidative stab ility. The fatty acid composition of the neutral lipids (NL) and phospholip ids (PL) of the membrane fractions were only slightly influenced by dietary fatty acid composition, Greater influence of dietary fatty acids was obser ved on the NL than on the FL. The mitochondrial fraction contained a higher content of unsaturated fatty acids (UFA) than the microsomal fraction. The AT content of the subcellular fractions increased with increasing levels o f dietary ATA. AT was between 1.7 and 2.5-fold higher in mitochondrial frac tions than in microsomal fractions. As the ATA content of RD diets increase d, the oxidation of membrane lipids decreased. More oxidation occurred in t he microsomal fraction compared to the mitochondrial fraction, which can be attributed mainly to a lower AT/UFA ratio in the microsomal fraction. (C) 2000 Society of Chemical Industry.