Variability within intramuscular fat content of pigs as measured by gravimetry, FTIR and NMR spectroscopy.

In order to determine in vivo intramuscular fat content of pigs' biceps femoris, three methods were compared. Gravimetry and FTIR spectroscopy after total fat extraction from a biopsy (about 400 mg skeletal muscle tissue) and in vivo (1)H NMR spectroscopy after imaging and volume of interest selection were used. Mean values (g fat/100 g fresh tissue) were, respectively, 1·47 ± 0·35 (gravimetry), 1·26 ± 0·33 (FTIR) and 0·51 ± 0·19 (NMR); but NMR-values represented only triglycerides. Within an intramuscular fat range from 1·1 to 2·7 g per 100 g fresh muscle tissue, possible to estimate a calibration line between the in vitro and in vivo data for hybrid piglets of about 18 kg. Repeated in vivo NMR measurements on the same muscle volume showed a mean coefficient of variation of 5·5 ± 2·7%. The coefficient of variation of measurements on different volumes within the same muscle was 14 ± 10%. The mean intramuscular fat content of 18 kg or 100 kg pigs was, respectively, 1·64 ± 0·46 (biceps femoris) and 1·32 ± 0·1 (longissimus dorsi) g per 100 g fresh muscle tissue.

Identification of halothane gene carriers by use of in vivo 31P nuclear magnetic resonance spectroscopy in pigs.

In vivo muscle 31P nuclear magnetic resonance spectroscopy was performed on 12 homozygous halothane-nonsensitive female pigs and 13 female pigs heterozygous with respect to the halothane gene. Fifteen female pigs of a third line, consisting of heterozygotes and halothane-nonsensitive homozygotes, were also available. Body weight ranged from 12 to 18 kg. Mean decrease in phosphocreatine concentration in the biceps femoris of anesthetized pigs was significantly lower for heterozygous vs homozygous pigs (3.46% vs 5.94%, P less than 0.01) after 40 minutes of halothane exposure (3%; oxygen flow, 3 L/min). Also, a statistically significant difference, with respect to the initial (7.21 vs 7.11, P less than 0.008) and end muscle pH values (7.18 vs 7.06, P less than 0.0002), was observed for homozygous vs heterozygous pigs. By means of canonical discriminant analysis, it was possible to distinguish nonsensitive homozygotes from heterozygotes (P less than 0.0001). When applying this classification method to pigs of the same strain, 2 populations (nonsensitive homozygotes, heterozygotes) emerged, with a proportion of pigs corresponding to the expected value on the basis of breeding records. In contrast to the phenotypic expression of muscular rigidity related to the malignant hyperthermia syndrome, the expression of metabolic variables (phosphocreatine, pH) was shown to be dominant.

In vivo muscle 31P nuclear magnetic resonance spectroscopy during treatment of halothane-sensitive and halothane-nonsensitive pigs.

In vivo muscle 31P nuclear magnetic resonance spectroscopy was performed on 10 female pigs originating from a homozygous halothane-sensitive line and on 10 female pigs from a homozygous halothane-nonsensitive line. The mean concentration of phosphocreatine in the biceps femoris muscle of the anesthetized pigs decreased to 86% of the initial value after 11 minutes of halothane exposure (3%, oxygen flow 3 L/min). After the next 5.6 minutes, phosphocreatine concentration reached a minimal value of 52%, followed by a mean recovery to 76% of the initial value during the ensuing 11 minutes. Response was not observed in anesthetized homozygous halothane-nonsensitive pigs. Thus, a decrease to 86% of the initial value of phosphocreatine was 100% predictive for homozygous halothane-sensitive pigs with body weight ranging from 10 to 18 kg.

Skeletal muscularity and heart function in growing piglets.

Nine female piglets (about 15 kg), originating from a line with a low skeletal muscularity, were compared to 9 female piglets (about 15 kg) originating from a line with a high skeletal muscularity. Electrocardiogram-parameters (frequency rise, ST-elevation, heart rate expressed as mean values per h) were measured for 17 h with an ambulatory Holter-device. Dimensions of longissimus dorsi muscle (depth, circumference, surface, speed of ultrasound) were measured with an ultrasound device based on the pulse echo principle. Parameters, with respect to muscular dimensions, were statistically significant, differing between both lines, whereas, only the ST-elevation was significant, lower in the high skeletal muscularity line. The lower muscular depth was, the higher the ST-elevation and the higher the mean lowest heart rate were, and the lower the speed of ultrasound through the muscle tissue, by the higher the mean frequency rise. Hence, in growing piglets of about 15 kg, an impairment of heart function coincides gradually with a proportional higher development of skeletal muscularity.