EFFECT OF EXTENSIVE FEEDING ON ALPHA-TOCOPHEROL CONCENTRATION AND OXIDATIVE STABILITY OF MUSCLE MICROSOMES FROM IBERIAN PIGS

The effect of extensive feeding, confinement and diet supplementation with alpha-tocopheryl acetate (100 mg/kg) on the fatty acid compositio n and tocopherol concentration of microsome extracts and their suscept ibility to oxidation was studied in Iberian pigs. The diet of pigs rai sed extensively teas mostly composed of acorn and grass. The alpha-toc opherol contents of acorn and grass were 20 and 171 mg/kg dry matter, respectively Microsomal fatty acid composition showed no differences a mong groups. Pigs feeding extensively had a higher concentration of cw tocopherol in muscle and microsomes than pigs given mixed diet with t he basal level of alpha-tocopheryl acetate (P<0.05) but lower values t han pigs given supplementary levels (100 mg/kg) (P<0.05). Microsomal f ractions from pigs given mixed diet with a basal level of alpha-tocoph eryl acetate were significantly more susceptible to iron induced lipid oxidation than extract from pigs given diets containing a supplementa ry level (P<0.05). Microsomal extracts from pigs feeding extensively h ad the lowest oxidation late (P<0.05), suggesting that other dietary c onstituents may play a role in the stabilization of microsomal lipids.