Effects of the malignant hyperthermia syndrome (MHS) on meat quality, muscle fibre characteristics end metabolic traits of the Longissimus muscle in Pietrain pigs

In Pietrain pigs with the genetic defect MHS (MHS group; n=11) and without this defect (MHR group; n=17) the Longissimus muscle was examined from the time of slaughter to 24 h post mortem to characterize endogenous changes in structural and functional parameters of the fibres and meat quality. At th e time of slaughter the muscle in the MHS group was characterized by enlarg ed fibre diameters, a reduced number of capillaries and an increased occurr ance of angular fibres and giant fibres. The fibre type composition in the MHS group tended to an increased proportion of glycolytic fibres and decrea sed proportion of oxidative fibres. The activities of four enzymes indicati ng the energy metabolism were not significantly different between the group s immediately after slaughter. However, at the time 45 min post mortem the activities of all enzymes were less in the MHS group as compared with the M HR group. The IMP/ATP quotient was the same in both groups directly after s laughter and was increased by 19.6 % in the MHS group 45 min post mortem in dicating a deficit in supply of ATP for the metabolic processes of developm ent from muscle to normal meat quality. Reduced values were measured in the sarcoplasmatic Ca2+ ATPase activity of the MHS group as compared with the MHR group. The changes in microstructure and metabolism of the muscle were related to an impairment of meat quality, which was characterized by a low pH value, lighter-coloured meat and a high drip-loss. The results underline the demand to eliminate those pigs with the MHS genetic defect from breedi ng stocks and to involve further traits of muscle into me selection.