Stress-resistant barrows were randomly assigned to groups of 15: I, control; II, hemorrhage 24 h before antemortem treatment; III, iv infusion of .45% NaCl 30 min before antemortem treatment; IV, iv infusion of 6% dextran (molecular weight 70,000) in saline 1 h before antemortem treatment and V, water deprivation for 48 h before antemortem treatment. Five barrows each within groups I through V were randomly assigned to three antemortem treatments: A, iv infusion 50% MgSO4 anesthesia; B, a forced walk of 100 m and electrical stunning (80 V for 20 s) and C, a forced walk, 5 min restraint with the use of a snare and electrical stunning. Postmortem muscle glycolysis was not affected by modification of fluid volumes before MgSO4 anesthesia or alteration of red-blood-cell mass in pigs exsanguinated under stress. However, an increase in fluid volume of the extravascular space accelerated postmortem glycolysis in pigs exsanguinated under stress. Thus, level of free water in muscle at exsanguination may control postmortem metabolism regardless of other antemortem extra- and intramuscular factors.
The study was performed on 31 samples of porcine muscle (m. longissimus dorsi) of different qualities, ranging from extremely pale, soft and exudative (PSE) to dark red in color, firm in structure and dry in appearance (DFD) in order to determine the water solubility of muscle proteins 24 hr post mortem. It was found that the water solubility of muscle proteins depends on the quality of the muscle, and is lowest in extremely PSE muscle. It was demonstrated, with the aid of electrophoresis on agar and acrylamide gels, that some sarcoplasmic proteins which undergo precipitation 30 min after adding a citrate-phosphate buffer (pH 4.6) at temperature of 20°C are extracted in smaller amounts from PSE muscle than from normal muscle. One of these fractions was benzidine positive.
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