Effects of supplemental magnesium aspartate and short-duration transportation on postmortem meat quality and gene expression of µ-calpain and calpastatin of finishing pigs

Twenty-four crossbred (Duroc × Large White × Yorkshire) finishing pigs (halothane-negative, mean live weight of 90 kg) were used to determine the effects of supplementing swine finishing diets with magnesium aspartate (MgAsp) and short-duration transportation stress on blood parameters, pork quality and μ-calpain and calpastatin mRNA levels in muscle of pigs. Transportation increased serum concentrations of calcium (Ca) (P < 0.05), phosphorus (P) (P < 0.01), glucose (P < 0.01) and cortisol (P < 0.01). Supplementation of MgAsp increased concentration of serum Mg (P = 0.057). Transportation decreased L⁎ value (P < 0.05) of biceps femoris (BF) at 45 min and 24 h, and b⁎ value of longissimus thoracis (LT) at 45 min (P = 0.073) after slaughter, and increased pH value of BF at 45 min (P < 0.05) and LT at 45 min (P = 0.098) after slaughter. However, transportation increased Warner–Bratzler shear force (WBSF) value of BF (P < 0.05) at aging 72 h and LT (P < 0.01) at aging 24 h and 72 h. Supplementation of MgAsp reduced L⁎ value (P < 0.05) of LT at 45 min, and BF at 45 min and at 24 h after slaughter, increased a⁎ value (P < 0.05) of BF at 45 min and had a trend to decline WBSF values of BF and LT at aging 24 h compared with the treatments fed the control diet. Transportation improved mRNA level of calpastatin of muscle (P < 0.05). Meanwhile, supplementation of MgAsp increased mRNA level of μ-calpain of muscle (P = 0.079). These results suggested that transportation stress increased postmortem color and pH value of pork and decreased tenderness of pork, and supplemental MgAsp improved color of pork and had a trend to decline WBSF, but did not influence drip loss and pH value of pork.