The effect of dietary magnesium oxide supplementation on postmortem 31P NMR spectroscopy parameters, rate of Ca 2+ uptake and ATPase activity of M. longissimus dorsi and meat quality of heterozygous and normal on malignant hyperthermia pigs

Abstract

Twenty four crossbred (Large White, White Meaty, Pietrain, Hampshire) pigs were tested by DNA probe for a mutation on the ryanodine receptor RYR1 (malignant hyperthermia-MH). An equal number of pigs heterozygote (monomutant-MON) and normal on MH (nonmutant-NON) were used in the experiment. The pigs were fed finisher feed (control group) or finisher feed supplemented with magnesium (3.6 g MgO per pig per day; MgO group) for 5 days prior to slaughter. Pigs fed the diet supplemented with MgO had higher plasma Mg concentrations. Phosphorus nuclear magnetic resonance ( 31P NMR) measurements on postmortem (15 min) muscle samples ( longissimus muscle) showed the highest phosphocreatine levels in normal pigs fed MgO ( P<0.05). The MgO supplementation caused increased Ca 2+ uptake and Ca 2+ ATPase activity only in normal (NON) pigs. ATPase activity was lowest ( P<0.05) in heterozygote control pigs. Pigs fed MgO supplemented diet had higher pH (45 min postmortem). A significant lower pH ( P<0.05) was obtained in heterozygous (MON) control pigs. Also pigs fed with MgO had lower percentage of drip losses and significant differences ( P<0.05) were obtained between heterozygous (MON) pigs. The results indicate that dietary MgO supplementation can improve parameters of muscle energetic metabolism, Ca 2+ uptake and meat quality (pH, drip loss).