A REVIEW OF THE CAUSES OF VARIATION IN MUSCLE GLYCOGEN CONTENT AND ULTIMATE pH IN PIGS

ABSTRACT Muscle glycogen at slaughter causes variation in pork technological qualities, since it affects the ultimate pH (24 h postmortem). This review addresses various factors influencing muscle glycogen storage and the ultimate pH of pig meat. Results discussed in this paper indicate that breed and preslaughter handling, i.e., waiting time in lairage, mixing, and to a lesser extent fasting, significantly influence ultimate pH. Furthermore, interactions between handling procedures and breed could be highly significant, as with PSE meat. Since the recent discovery of the major gene rn + /RN − which is assumed to influence glycogen concentration in the muscle of live pigs, genotype is considered an important source of variation in ultimate pH. All factors likely to influence glycogen concentration must be considered relative to the metabolic and contractile properties of muscle. These play an important role in the amount of glycogen at rest and in its depletion during chronic stress or muscular exercise.