POST-MORTEM METABOLISM OF GLYCOGEN IN THE WHITE AND MIXED TYPE MUSCLES OF THE DOMESTIC-FOWL

During 24 hours post mortem, we observed the glycogen content and its change, lactate formation and pH changes in muscles of the domestic fowl. For analyses we used m. pectoralis major, which comprises up to 93 per cent of white fibres, and thigh muscles, which are mixed as to their fibre type, described as red muscles. As expected, m. pectoralis major, as a white muscle, contains more glycogen than the mixed thigh muscles. In keeping with that, more lactate is produced post mortem in the breast muscle than in the thigh muscles. Kinetics of lactate formation is about the same in the breast and thigh muscles in the first 105 min. but afterwards the glycogen reserve in the thigh muscles decreases, so that further glycolysis takes place only in the breast muscle. pH values decrease regularly also in the first 105 minutes and then in correspondence with higher lactate formation they run down at a higher rate in the breast muscles. It is clear from this histochemical glycogen determination that its depletion is in progress in most white fibres of the m. pectoralis major. In the thigh muscles the depletion occurs in all three types of fibres, but is not regular and shows no clear glycogen degradation in certain type of fibres. The results of the study show that the glycogen content and the pattern of glycolysis are different from the values and patterns of these processes in mammals' muscles.