Influence of rearing conditions and crossbreeding on muscle color in Iberian pigs

The effects of pig crossbreeding (Iberian versus Iberian x Duroc 50%) and r earing conditions (outdoors versus indoors) on muscle fiber composition, my oglobin content and objective muscle color in biceps femoris and tibialis c ranealis muscles have been studied. Muscle fibers were identified as types I, IIA, IIB, oxidative IIB and IIC and the proportion of each fiber type wa s determined by a computerized image analysis. Color co-ordinates L*, a*, a nd b* were measured and both chroma (C*) and hue angle (h degrees) were cal culated. Myoglobin content and chroma value were significantly higher in ti bialis cranealis muscle than in biceps femoris muscle (p less than or equal to 0.001), whereas the former muscle showed the lowest lightness and hue a ngle values (p less than or equal to 0.001). Moreover,tibialis cranealis mu scle exhibited a higher total proportion of oxidative fibers, types I, IIA and IIBx (p less than or equal to 0.05), and a lower fat content than did b iceps femoris muscle (p less than or equal to 0.001). The muscles of pigs r eared outdoors tended to show a higher percentage of oxidative fibers (type I) than did muscles from indoor reared pigs, although not to a significant extent. Rearing conditions significantly affected color, muscles from outd oor reared pigs exhibiting higher lightness (L*), chroma (C*) and hue angle (h degrees) than muscles from indoor reared pigs. However, neither the cro ssbreeding nor the rearing conditions showed a significant influence on myo globin concentration of muscles.