THE EFFECT OF ANTEMORTEM ELECTROLYTE THERAPY ON ANIMAL PHYSIOLOGY ANDMEAT QUALITY IN PIGS SEGREGATING AT THE HALOTHANE GENE

The present study was initiated to investigate the effect of oral pota ssium (600 mg, slow release, 24 h preslaughter), intramuscular (IM) ma gnesium (500 Mg MgSO4, 2 h preslaughter) or slow release magnesium (Ma gnesium-aspartate-hydrochloride (Mg Asp) 20 or 40 (g d-1 for 5 d) on a nimal physiology and pork quality. Experiments were undertaken on 318 barrows and gilts (100 kg +/- 5 kg) represented by three genotypes seg regating at the halothane locus (nn, Nn and NN genotypes). Experiment 1 indicated that the oral potassium effectively (P less-than-or-equal- to 0.05) reduced pCO2 values in die nn genotype. Intramuscular injecta ble magnesium treatments were also found to raise plasma magnesium (P < 0.05) but did not alter muscle, liver or heart tissue levels. Both o ral potassium and i.m. magnesium exacerbated subjective pork structure and texture scores but were found to increase muscle brightness and h ue (higher b value). In exp. 2, oral magnesium-aspartate (Mg Asp) was found to raise plasma, but not tissue, levels of magnesium. When fed to a group of halothane carrier pigs (Nn genotype), Mg Asp reduced mus cle temperature 45 min post-stunning, increased muscle redness (CIE a value) and reduced muscle drip loss (P < 0.06). It was concluded that oral potassium and i.m. magnesium as administered in the present stud y had no beneficial effects on pork quality but that the beneficial ef fects of Mg Asp on meat colour and drip loss may warrant further inves tigation.