Lipid oxidation was assessed on the basis of the malondialdehyde (MDA) in the examined samples. MDA, the compound used as an index of lipid peroxidation, was determined by a selective third-order derivative spectrophotometric method previously developed by some of the authors (Botsoglou et al., 1994). In brief, 2 g liver samples were homogenized (Polytron homogenizer, D-9, Germany) in the presence of 8 ml of 5% aqueous trichloroacetic acid and 5 ml of 0.8% butylated hydroxytoluene in hexane, and the mixture was centrifuged