Effects of muscle mass and fiber type composition of Longissimus dorsi muscle on postmortem metabolic rate and meat quality in pigs

The carcass traits, the muscle fiber characteristics and the meat quality traits were evaluated using 200 crossbred pigs. The muscle mass was divided into heavy or light groups according to the carcass weight and the loin-eye area measurements. In addition, the proportion of the fast-twitch glycolytic muscle fiber was divided into high or normal groups according to the area percentage of type IIb fiber. Heavier pigs contained larger loin-eye area and muscle fibers, and also had more total muscle fibers than the lighter ones. The high group showed lower muscle pH, protein solubility, and also showed higher R-value, drip loss and lightness than the normal group. These results suggest that an increase in total fiber number combined with a higher percentage of oxidative muscle fibers has a beneficial effect on increasing the muscle mass without deteriorating the meat quality.