THE EFFECTS OF EXERCISE ON MUSCLE-FIBER COMPOSITION AND OXIDATIVE CAPACITY IN 8 BOVINE SKELETAL-MUSCLES

Ten Swedish dairy cows (2 Swedish Friesian and 8 Swedish Red & White, age 4-8 years) were included in the study. Four cows were constantly t ied, while 6 cows had access to pasture during the summer months, May- September. This study was undertaken in order to assess the effects of exercise on muscle fibre composition, fibre area, capillary density a nd oxidative capacity of eight bovine muscles. The relationships betwe en these traits and meat quality traits are discussed. The study also gave a picture of the muscle fibre-type composition and showed that th e variation between muscles was considerable. One type of fibre, which may be designated as a giant fibre, constituted a large proportion in M. infraspinatus and M. supraspinatus and showed, by histochemical st aining, typical oxidative properties. The physical exercise obtained f rom grazing did not change the fibre composition, capillary density, o r the oxidative capacity of the muscles. It can therefore be claimed t hat the exercise effect of grazing is of limited importance regarding the traits studied.