Effect of dietary copper and vitamin E supplementation, and extensive feeding with acorn and grass on longissimus muscle composition and susceptibility to oxidation in Iberian pigs.

The objective of this study was to assess the effect of dietary copper and/or vitamin E supplementation on composition and oxidation of M. longissimus in Iberian pigs and to compare it with meat samples from pigs produced extensively and fed with acorn and grass. Grass had the highest alpha-tocopherol content (> 150 mg/kg DM), while acorns had the highest copper concentration (78.1 mg/kg DM). Dietary treatment did not affect copper composition in muscle and no interactions were detected between copper and alpha-tocopherol. The alpha-tocopherol content in muscle from pigs fed diets supplemented with alpha-tocopheryl acetate (100 mg/kg feed) was 1.5 times greater (p < 0.0001) than those from pigs receiving a basel diet. M. longisssimus dorsi from pigs fed extensively had a higher concentration of alpha-tocopherol than those fed in confinement with the basel level of alpha-tocopheryl acetate, but lower values than pigs fed supplemented levels. Total n-3 fatty acids (p < 0.02) and hematin (p < 0.0001) concentrations were significantly higher in muscle from pigs fed extensively than when fed in confinement. Muscle homogenates from Iberian pigs fed in extensive conditions showed significantly (p < 0.02) higher susceptibility to oxidation than those from pigs fed mixed diets. Dietary alpha-tocopheryl acetate supplementation (100 mg/kg feed) significantly (p < 0.05) reduced lipid oxidation of muscle, while dietary copper concentration did not modify susceptibility to lipid oxidation.