Comparison of accuracy of intramuscular fat prediction in live pigs using five different ultrasound intensity levels.

The objective of this study was to evaluate the possibility of prediction of intramuscular fat (IMF) in live pigs using ultrasound method. Moreover, the accuracy of prediction at five different ultrasound intensity levels was investigated. Cross-sectional images of longissimus dorsi muscle (LD) at right last rib area, from hybrid pigs, were taken. Each pig was scanned at the same frequency (3.5 MHz) and at the five different ultrasound intensity levels 70%, 75%, 80%, 85% and 90% of total amplifying of sonograph, using the device ALOKA SSD-500. The video image analysis was used to predict IMF content (ultrasound intramuscular fat (UIMF) 70 to UIMF90). The second day after slaughter, the dissection of right half carcass was done. A sample of LD at the last rib was taken for laboratory analysis of IMF content (LAIMF). Scatter plots with UIMF on the x-axis and LAIMF on the y-axis were constructed to account for individual variability within and between intensity levels. Correlations between LAIMF and UIMF were significantly different from zero (r = 0.40-0.52), except for correlation between LAIMF and UIMF90 (r = 0.14). Statistical model with LAIMF (the dependent variable), UIMF (the same model for each intensity level), live weight (the covariates) and sex (the fixed effect) was developed. Coefficients of determination (R2) were 0.33, 0.38, 0.34, 0.25 and 0.17 with UIMF at the intensity level 70%, 75%, 80%, 85% and 90%. Root mean square errors ranged from 0.516% to 0.639%. Standard errors of individual prediction ranged from 0.523% to 0.649%. Goodness-of-fit of the model was also justified by testing the residuals for normality. Although the results are not quite unequivocal in favour of the one intensity level, it seems that intensity levels 75% and 80% are the most suitable to predict IMF in live pigs. Further research is needed, mainly to increase accuracy of collecting, processing and evaluating the sonograms using video image analysis.

The effect of dietary magnesium oxide supplementation on postmortem (31)P NMR spectroscopy parameters, rate of Ca(2+) uptake and ATPase activity of M. longissimus dorsi and meat quality of heterozygous and normal on malignant hyperthermia pigs.

Twenty four crossbred (Large White, White Meaty, Pietrain, Hampshire) pigs were tested by DNA probe for a mutation on the ryanodine receptor RYR1 (malignant hyperthermia-MH). An equal number of pigs heterozygote (monomutant-MON) and normal on MH (nonmutant-NON) were used in the experiment. The pigs were fed finisher feed (control group) or finisher feed supplemented with magnesium (3.6 g MgO per pig per day; MgO group) for 5 days prior to slaughter. Pigs fed the diet supplemented with MgO had higher plasma Mg concentrations. Phosphorus nuclear magnetic resonance ((31)P NMR) measurements on postmortem (15 min) muscle samples (longissimus muscle) showed the highest phosphocreatine levels in normal pigs fed MgO (P<0.05). The MgO supplementation caused increased Ca(2+) uptake and Ca(2+) ATPase activity only in normal (NON) pigs. ATPase activity was lowest (P<0.05) in heterozygote control pigs. Pigs fed MgO supplemented diet had higher pH (45 min postmortem). A significant lower pH (P<0.05) was obtained in heterozygous (MON) control pigs. Also pigs fed with MgO had lower percentage of drip losses and significant differences (P<0.05) were obtained between heterozygous (MON) pigs. The results indicate that dietary MgO supplementation can improve parameters of muscle energetic metabolism, Ca(2+) uptake and meat quality (pH, drip loss).

In vitro (31)P NMR studies on biopsy skeletal muscle samples compared with meat quality of normal and heterozygous malignant hyperthermia pigs.

Phosphorus nuclear magnetic resonance ((31)P NMR) measurements were made to determine muscle energetic metabolism on muscle biopsy samples of heterozygote malignant hyperthermia (Nn) and normal (NN) pigs DNA tested on occurrence of mutation in RYR 1 gene. Biopsy samples (approx. 1 g) were obtained by spring-loaded biopsy instrument (Biotech, Slovakia) from Longissimus dorsi (LD) muscle at 80 kg live weight. The spectra were recorded at 121 MHz on a VXR 300 (Varian) spectrometer in 10 mm diameter tube (maintained at 39 °C) for 50 min. pH of bioptates after NMR measurements were also measured at 60 min. The changes in inorganic phosphate (Pi), phosophocreatine (PCr) and adenosine triphosphate (ATP) were faster in heterozygote malignant hyperthermia (MH; 29 crossbred White Meaty×Pietrain) than in normal (13 Duroc, Yorkshire and White Meaty). The values of PCr at 20 min and pH at 60 min after taking biopsy allowed discrimination between NN and Nn pigs and significant (P<0.05) differences were also found between two subgroups in heterozygote MH pigs with different rate of post mortem muscle metabolism. The values of PCr and pH as measured at definite time on the biopsies, were significantly (P<0.05) correlated with the rate of post mortem metabolism (pH) and with meat quality traits (r approx. 0.4-0.6). The (31)P NMR measurements pointed to impaired muscle energetic metabolism connected with the occurrence of mutation on the RYR 1 gene in heterozygote MH pigs.

Effect of preslaughter handling on muscle glycogen level and selected meat quality traits in beef.

The ante-mortem and post-mortem glycogen levels in bull muscle were studied to determine their influence on the ultimate pH, cooking loss and shear force. Forty-three bulls (13 Holstein, 12 crosses Holstein × Belgium blue, 9 Slovak Pied and 9 crosses Slovak Pinzgauer × Piemontese) were tied, housed and divided in control (A, n = 30) and stressed (B, n = 13) groups before slaughter. At the institute abattoir, the group B animals were mixed and kept overnight. In group A, bulls were slaughtered immediately after arrival at the abattoir. The following values of muscle were determined: (1) glycogen ante mortem from m. semitendinosus (ST) (biopsy technique, Biotech Nitra), (2) glycogen post mortem (1 hr, 3 hr, 48 hr) from longissimus dorsi muscle (LD), (3) ultimate pH, cooking loss and shear force 48 h post mortem. The results show that the glycogen concentrations ante mortem (ST) and 1 hr post mortem (LD) from unstressed animals were similar (p > 0.05). The ante-mortem and post-mortem (1 hr, 3 hr) muscle glycogen concentration were depleted (p < 0.01) in all stressed bulls. Differences between stressed and unstressed animals (p < 0.01) were found in ultimate pH, cooking loss and in shear force (p < 0.05). Significant correlations (p < 0.01) between ante-mortem (ST) and postmortem (LD, 1 hr, 3 hr) muscle glycogen and ultimate pH and cooking loss supported the possibility of using an efficient biopsy technique in combination with a simple method of glycogen estimation (iodide method) to predict metabolic exhaustion (glycogen depletion) and/or dark cutting condition of bulls.

Meat quality assessed Ante- and Post mortem by different ryanodine receptor gene status of pigs.

Different breeds and crossbreeds (total 63) of pigs with defined genotype (DNA based test on RYR 1 gene status) were divided in normal (non mutant), heterozygotes (carriers, monomutant) and homozygote positive (dimutant) animals. Muscle biopsy samples were taken at approximately 80 kg live weight using an efficient non-stress spring-loaded biopsy instrument. After incubation of muscle samples (39 °C, 1 hr) analyses pH, WHC (fluid), R value (ITP:ATP) were performed. After slaughter, meat quality values (pH(1), pH(24), R value, colour, drip loss) were also carried out. Heterozygotes were intermediate and between both homozygote pig groups in most meat quality values analysed. Using WHC (fluid volume) values (0.45 and 0.48 respectively) it was possible to divide heterozygotes into two groups, each closer to homozygotes. The values of pH, WHC (fluid), as measured at definite times on the biopsies, were correlated with the pH(1) post-mortem value (r approx 0.6-0.7). The results support previous findings on the possibility of differentiating pigs within DNA test-defined groups. Introducing the gene into a pig population could be useful, in improving leanness and muscling: but meat quality is certain to deteriorate. Further experiments are needed to support the possibility of identifying PSE-prone pigs from among normal non mutant pigs.

[Physiologic, biochemical and genetic aspects of malignant hyperthermia]. / Fyziologické, biochemické a genetické aspekty malígnej hypertermie.

Malignant hyperthermic syndrome (MHS) is based on a metabolic dysfunction of the skeletal muscle. It is characterized by an elevation of muscle metabolism and rigidity, accompanied by an increase of arterial pCO2, lactate and potassium plasma concentration, and body temperature. In sensitive individuals, MHS can be evoked pharmacologically. To identify substances that evoke this syndrome or those useful for its therapy, MHS is modelled in pigs. The primary defect attributed to MHS is the impairment of sarcoplasmic calcium homeostasis based on a dysfunction of one of calcium ion channels. In some cases, genetic mapping has shown that MHS is related to changes in 19 chromosome (in humans). Abnormal function of the ion channel is probably not sufficient for the expression of MHS. The syndrome manifests only when several modifying factors coincide.

A comparison of some metabolitesin skeletal muscle of different halothane sensitivity withmeat quality traits of pigs using a capillary isotachophoresis technique.

Isotachophoretic (ITP) measurements were made on biopsy samples from live muscle M. longissimus lumborum and carcasses of pigs. Two experiments were performed. In Experiment 1, the methodological aspects of ITP measurements from skeletal muscle, were studied. In Experiment 2, ITP measurements on muscle and carcass samples were made. The muscle and carcass samples were obtained by shot or spring-loaded biopsy from the Longissimus lumborum muscle of 30 Belgium Landrace × Duroc pigs, of which 10 were halothane-positive. The pigs were slaughtered by electro-stunning and manguination at approximately 105 kg body l. w. The potential meat quality in live pigs and after slaughter using small biopsy samples of M. longissimus lumborum was also determined. The experimental results show that ITP (mainly inosinemonophosphate and lactate) and meat quality data (water-holding capacity test, pH and R value) can differentiate halo thane-positive from halothane-negative pigs. Out results confirmed previous results which showed that the water-holding capacity test defined as fluid volume', pH and R value measurements on biopsy samples can also predict the potential meat quality in live pigs.

Identification of halothane genotypes by calcium accumulation and their meat quality using live pigs.

The three halothane genotypes (NN, Nn, and nm) were identified by measuring the capacity for Ca(2+) accumulation by sarcoplasmic reticulum in whole muscle homogenate preparations of M. longissimus dorsi with a Ca(2+) specific electrode at 35°C. Significant differences (P < 0·001) in deterioration (%) of Ca(2+) accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed after ageing the whole muscle homogenate preparations for 24 h in ice. Predictions of meat quality in live pigs (n = 34) based on the values for water-holding capacity, assessed as fluid (g/0·5 g wet wt LD), and pH (fluid) by using small biopsy LD samples (Cheah et al. 1993) were performed on all the halothane genotypes. The halothane genotype NN (n = 11) showed a fluid value of 0·37 ± 0·01 and a pH (fluid) value of 6·62 ± 0·03 as compared with 0·61 ± 0·02 and 5·84 ± 0·04, respectively, for the halothane genotype nn (n = 13). The Nn pigs (n = 10) showed fluid (0·49 ± 0·03) and pH (fluid) (6·19 ± 0·11) values between those values observed for the two homozygotes (NN and nn). Predictions of meat quality in live pigs from biopsy LD muscles were confirmed from assessments on post-mortem LD muscles based on pH(1) and fibre optic probe (FOP) measurements. The extent of deterioration (%) in Ca(2+) accumulation showed high correlations with fluid (r = -0·861) and pH (fluid) (r = -0·831) in the biopsy LD samples, and with pH(1) (r = 0·663), FOP (r = -0·812), and drip (%) loss (r = -0·777) in the post-mortem LD samples.

Evaluation of halothane sensitivity and prediction of post-mortem muscle metabolism in pigs from a muscle biopsy using (31)P NMR spectroscopy.

Phosphorus nuclear magnetic resonance ((31)P NMR) measurements were made on biopsy samples from pig muscles. Two experiments were performed, one in France and one in Czechoslovakia. In experiment 1, the muscle samples were obtained by surgery from the Biceps femoris muscle of 10 pigs with various genetic types (5 Large White, 1 Large White × Landrace, 4 Pietrains). In experiment 2, the muscle samples were obtained by shot biopsy from the Longissimus dorsi muscle of 11 Belgian Landrace × Duroc pigs, of which 6 were halothane-negative and 5 halothane-positive. The pigs were slaughtered by electrostunning and exsanguination respectively 3 weeks and 1 week after the biopsy, and meat quality traits (pH(1), reflectance and water holding capacity) were determined. The changes in adenosine triphosphate (ATP), creatine phosphate (CP), inorganic phosphate (P(i)) and pH, as deduced from NMR, were faster in Pietrains than in Large Whites, and in halothane-positive than in halothane-negative pigs. The value of the CP/P(i) ratio at 40 min after taking biopsy allowed discrimination between halothane-positive and halothane-negative pigs. The values of pH, creatine phosphate and adenosine triphosphate, as measured at definite times on the biopsies, were correlated with the rate of post-mortem metabolism (r approx 0·8) and with meat quality traits. (31)P NMR measurements combined with a rapid and efficient biopsy technique appear as an alternative tool for assessment of both halothane sensitivity and prediction of meat quality in pigs.

Prediction of meat quality in live pigs using stress-susceptible and stress-resistant animals.

A new in-vivo procedure for predicting the potential meat quality in live pigs was devised using stress-susceptible (halothane positive) and stress-resistant (halothone negative) pigs. The potential meat quality in live pigs was determined using small biopsy samples of M. longissimus dorsi (LD). Meat quality was assessed by the combined measurements of pH and water-holding capacity (WHC) on the 12 000 g supernatant after incubation of 500 mg biopsy LD muscle with an equal volume of 150 mm KCl at 39°C for 45 min. With the LD muscles of halothane positive (n = 37) and halothane negative (n = 55) pigs, high correlations (r = -0·854) were observed between the supernatant (i.e. fluid) pH and WHC of the biopsy samples, between fluid pH of the biopsy samples and 1-h post-mortem (pH(60)) LD muscles (r = 0·951), and between pH(60) and WHC (r = -0·956). The experimental data show that our in-vivo test can differentiate halothane positive from halothane negative pigs and can also predict the potential meat quality in live pigs. The test could be applied to select pigs with differences in WHC to improve meat quality.

Respiratory chain defect of myocardial mitochondria in idiopathic dilated cardiomyopathy of Doberman pinscher dogs.

Idiopathic dilated cardiomyopathy (IDCM) is a primary myocardial disease of unknown cause. We tested the hypothesis that IDCM was associated with a myocardial metabolic defect by determining a comprehensive biochemical profile of metabolite concentrations and enzyme activities for the major metabolic pathways of the myocardium. We used the Doberman pinscher breed as a naturally occurring canine model of IDCM and compared its myocardial profile with that of healthy adult mongrels. Compared with controls, myocardium in IDCM had markedly reduced mitochondrial electron transport activity and myoglobin concentration, in association with acidosis and energy depletion following anoxic challenge: 60% decreased NADH dehydrogenase and 50% decreased ATP synthetase activities; 90% decreased myoglobin concentration; and 30% reduced ATP and 50% increased lactate and proton concentrations. Sarcoplasmic reticulum Ca(2+)-transport ATPase was decreased by 42%. There was a 15% compensatory increase in fatty acid oxidation and Krebs cycle activity. Other biochemical changes were mild by comparison with the mitochondrial defects. We conclude that IDCM is associated with a marked impairment of mitochondrial production of ATP, arising from decreased activity of the mitochondrial electron transport system, including myoglobin. These changes may be secondary to an underlying genetic defect or may indicate a deficiency of the mitochondrial respiratory chain that predisposes this breed to heart failure.

Shot biopsy in view of muscular disorders in pigs.

Although a number of problems in connection with the use of shot biopsy have yet to be solved, it can be stated that by this technique biopsy samples of sufficient quantity (up to 1.5 g) can be obtained from the musculus longissimus dorsi of pigs of about 80 kg liveweight. The technique offers data on the metabolic status (biophysical and biochemical values) of muscles, provided that the postmortal processes have been simulated (incubation of bioptate). The use of sensitivity tests on isolated subcellular fractions of the bioptate can lead to more precise results and consequently, to a remarkable reduction in the incidence of PSE syndrome (pale, soft, exudative meat). The first results achieve under conditions of Slovakia (Czechoslovakia) in testing boars show that this method could find a permanent use in the practice. Research institutions in a number of countries are now investigating possibilities of using shot biopsy for prediction of skeletal muscle disorders in pigs and it is excepted that many new results will be published soon.