Abstract
The effect of swimming exercise on retardation of softening of flesh was examined with cultured red sea-bream Pagrus major (2 years old) exercised for 0 (control) or 12h a day during 1, 2 or 4 weeks in water flow of 2.5 BL (body length)/s. Fish were instantly killed by exsanguination and stored in ice for 12 days. Pieces of ordinary muscle of the dorsal part and caudal part were sampled from the iced fish every 2 days up to the 12th day, and myofibrils were prepared from the muscle. The number of sarcomeres composing the myofibrils was counted under a microscope. The fre-quency in percentage of F1-4, myofibrils composed of 1 to 4 sarcomeres, was used as an index of softness of the flesh. The frequency of F1-4 increased during storage faster in the cultured fish than in the wild ones, and slower in exercised fish than in nonexercised ones among cultured fish, especially at the caudal muscle. These results suggest that the flesh texture of cultured red sea-bream may be improved by swimming exercise.
