The relationship between pig genetics, myosin heavy chain I, biochemical traits and quality of M. longissimus thoracis

The relationship between muscle biochemical traits, myosin heavy chain I and meat quality of longissimus thoracis was studied using gilts from five divergent porcine lines (A to E) (carcass weight: 83.7±8.7 kg). Intramuscular fat (IMF) and haem pigments content as well as myosin heavy chain 1 (MyHC I) percentage and the activity of lactate dehydrogenase (LDH) and isocitrate dehydrogenase (ICDH) were determined. Only group E, a well conformed line of pigs, included the halothane positive genotype. The presence of the Hal gene in this line resulted in meat of poorer quality in terms of meat of higher exudate compared to line D, also a well conformed line of predominantly Pietrain origin but being halothane gene free. Line C presented the highest IMF content (2.02%) as well as high oxidative characteristics (MyHC I, 10.0%; LDH/ICDH, 1.92 μmol nmol −1; ICDH activity, 1.78 nmol min −1 g −1) and the lowest drip losses (5.3%). According to a principal component analysis including MyHC I, biochemical traits and meat quality parameters, line C was characterized by a high IMF content and oxidative traits, and line B by a high glycolytic metabolism. Line E was distinguished by high drip losses and by low pH 45 and pH u. In conclusion, several observed differences in muscle metabolism between lines free of the halothane gene (A, B, C and D) must be caused by other “genetic background” factors.