One-hundred-and-twenty-nine pigs from four genetic types-Large Whites, halothane-negative (HN) and halothane-positive (HP) Pietrains and Hampshires-were used to study some compositional and enzymatic muscle traits. Water, nitrogen, hydroxyproline and lipid contents, as well as lactate dehydrogenase and citrate synthase activities, were measured on all pigs, whereas glycogen phosphorylases (a and a + b), glycogen synthetase I + D and myosin isozyme pattern were determined on only fifty-six pigs. Hampshires were markedly different from the other genetic types with respect to the characteristics studied. Their Longissimus dorsi muscle contained less nitrogen (P < 0·0) and more lipid (P < 0·01) and presented higher hydroxyproline to nitrogen (P < 0·001) and water to nitrogen (P < 0·001) ratios, as well as noticeably higher citrate synthase (P < 0·01) and glycogen synthetase.

This paper presents a study of the metabolic and contractile types of 34 samples from 30 muscles in five crossbred Pietrain-Large White pigs 6 to 7 months old. The activity of the following enzymes was measured: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase using high (LDH-h) or low (LDH-b) pyruvate concentrations in the reaction medium, citrate synthase (CS), and myofibrillar Ca-Mg activated ATPase. Haeminic iron and ultimate pH (pHu) were measured on the same samples. The results showed a negative, rather linear relationship between GAPDH, LDH and ATPase activities on the one hand and CS and haeminic iron on the other. Rather high correlations (r = 0.7 to 0.8) were observed between metabolic and contractile criteria and pHu; the red (slow) muscles had the highest pHu.

Enzyme, metabolic and contractile activities in 30 pig muscles and their relationship with ultimate postmortem pH.This paper presents a study of the metabolic and contractile types of 34 samples from 30 muscles in five crossbred Pietrain-Large White pigs 6 to 7 months old.The activity of the following enzymes was measured : glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase using high

water binding capacity), FOP and TEST values on different muscles.For the « best » 2-variable equations, which combine the pH24 of Adductor femoris (AF) or Biceps femoris (BF) and the subjective score for wetness, R was around 0.72.For the « best » 3-variable equations, where the same variables as above were combined with one FOP measurement, R was around 0.76.When using only pH24 or FOP measurements which can be taken without cutting the carcass R was around 0.68 and 0.72 with the best 2 and 3 variable prediction equations, respectively.A new « meat quality index » (MQI) was established on the basis of these results for use in progeny-testing stations : MQI was a 3-variable linear combination of pH24 of AF muscle, REF and TGW of BF muscle, and the corre- lation between MQI and TY was 0.718.