Lipid and protein oxidation in microsomal fraction from turkeys: influence of dietary fat and vitamin E supplementation.

The objectives of this study were to investigate the effects of dietary fats (6% soya oil or rapeseed oil or tallow) and α-tocopheryl acetate supplementation (30 ppm for control and 200 ppm for supplemented animals), on lipid and protein oxidation, induced by Fe(3+)/ascorbate, of microsomal fraction in turkey muscles (M. pectoralis major and M. sartorius). Supplementation of turkeys with α-tocopheryl acetate increased the vitamin E content of microsomal membranes. Vitamin E supplementation strongly decreased lipid oxidation in membranal fractions when animals were fed rapeseed oil or tallow; this effect was less pronounced in animals fed soya oil. Vitamin E supplementation induced a slight decrease in protein carbonyl content, especially in animals fed soya oil. Level of protein free thiols was considerably enhanced in diet enriched with soya oil. Vitamin E supplementation had a stabilizing effect on glucose-6-phosphatase activity of microsomes when oxidized by Fe(3+)/ascorbate. No muscle effect was detected on the level of lipid and protein oxidation in membranal fractions even if M. sartorius is known to be more oxidative than M. pectoralis major.