Halothane Gene Research Articles

The effect of ante mortem electrolyte therapy on animal physiology and meat quality in pigs segregating at the halothane gene

The present study was initiated to investigate the effect of oral potassium (600 mg, slow release, 24 h preslaughter), intramuscular (IM) magnesium (500 mg MgSO4, 2 h preslaughter) or slow release magnesium (Magnesium-aspartate-hydrochloride (Mg Asp) 20 or 40 (g d−1 for 5 d) on animal physiology and pork quality. Experiments were undertaken on 318 barrows and gilts (100 kg ± 5 kg) represented by three genotypes segregating at the halothane locus (nn, Nn and NN genotypes). Experiment 1 indicated that the oral potassium effectively (P ≤ 0.05) reduced pCO2 values in the nn genotype. Intramuscular injectable magnesium treatments were also found to raise plasma magnesium (P < 0.05) but did not alter muscle, liver or heart tissue levels. Both oral potassium and i.m. magnesium exacerbated subjective pork structure and texture scores but were found to increase muscle brightness and hue (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 muscle 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 study had no beneficial effects on pork quality but that the beneficial effects of Mg Asp on meat colour and drip loss may warrant further investigation. Key words: Magnesium, potassium, preslaughter, pork quality, PSE pork

Detection of the ryanodine receptor mutation associated with malignant hyperthermia in purebred swine populations1

A restriction endonuclease assay (REA) that reveals a C/T transition in the ryanodine receptor gene (ryr-1 locus) was proposed to test swine for malignant hyperthermia. The REA was tested in a heterologous pig population of 1,227 individuals representing Hampshire, Duroc, Landrace, and Yorkshire breeds. Of this group, 713 pigs had been classified on the basis of the halothane challenge and progeny testing into the three possible Hal genotypes (685 negatives, 24 carriers, and 4 susceptibles). The REA confirmed the four susceptibles as T/T, 17/24 carriers as C/T, and 659/685 negatives as C/C. The rest of the sample was constituted of 514 pigs that had not been selected on the basis of the halothane gene. The proportions of C/T and T/T pigs within the breeds represented were 3.2 and 1.6% for Duroc, 27.3 and 1.4% for Landrace, and 17.9 and 1.9% for Yorkshire. No T/T allelic pairs were found in the Hampshire breed, although the sample was very small. Genotypic distribution and allelic frequencies at the ryr-1, Phi, and Pgd loci were reported among the breeds.

Electrocardiogram parameters of piglets during housing, handling and transport

AbstractTelemetric techniques for the monitoring of physiological parameters during housing, handling and transport may help producers to reduce mortality and improve meat quality. In order to know the reliability of electrocardiogram parameters as stress indicators, piglets (12 to 23 kg) being different with respect to the halothane gene (homozygous halothane sensitive (nn) and non-sensitive (NN), heterozygotes (nN)), and thus different with respect to stress susceptibility, were monitored with an ambulatory ECG device during housing, handling and transport. Skeletal muscularity of all animals was measured with an ultrasound device.Heterozygotes and homozygote halothane sensitive piglets had a higher muscularity, but only the homozygotes had a higher ST-elevation from the isoelectric line of the QRST-complex of the electrocardiogram when measured within housing conditions. This means a different propagation of the electric current related to the activation of the ventricle. Halothane gene carriers (Nn and nn piglets) had a statistically significant higher mean maximal heart rate during housing conditions. During handling heart rate rose by 14·8%, 0·61% and 42·9% respectively for NN, nN and nn piglets, with nn piglets having the highest values. During transport these measurements were respectively 6·88%, 3·66% and 9·7% higher for lines NN, nN and nn as compared with those in housing conditions. Heart arrhythmicity parameters were not different between housing and transport, but during handling up to a 23-fold increase could be observed.Heart rate and arrhythmicity parameters may generate reliable information to monitor stress during housing, handling and transport of piglets through genotypes and skeletal muscularity.

The effects of breed and halothane sensitivity on pig meat quality

The effects of halothane sensitivity and breed (Belgian Landrace BL and Landrace L), and their interactions on carcass and meat quality were analysed. Also the effect of breed (Pietrain P, BL, L, Large White LW and Duroc D) on carcass and meat quality was studied in a sample of 153 gilts. Each of the half-carcasses was cut and fully dissected to obtain lean percentage. The following measurements of meat quality were carried out: muscle pH, electrical conductivity (QM) and light scattering (POP). Muscle reflectance (GOFO value), muscle protein solubility (MPS) and intramuscular fat content were also determined. The results obtained in this study revealed the effect of halothane gene on all of the traits studied. The halothane-positive animals showed less fat thickness and more lean percentage in the carcass. The P and BL breeds had more lean percentage in the carcass and a better lean-to-bone ratio compared with L, LW and D. The L breed was intermediate. Stress sensitivity is an important factor affecting the inverse relationship between carcass quality and meat quality. Those breeds free of the halothane gene (LW and D) had the best meat quality. The L breed was in an intermediate position, but more similar to halothane-negative breeds. The Duroc breed had significantly higher intra-muscular fat (>2·0%), required for optimum fresh meat quality and for the production of Spanish dry-cured ham of high quality.

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

SUMMARY 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 < 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 < 0.008) and end muscle pH values (7.18 vs 7.06, P < 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 < 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.

Halothane gene and swine performance.

One hundred thirty-one pigs representing seven different breed groups (Minnesota No. 1 [M], Pietrain [P], Yorkshire [Y], and crosses PY, P[PY], P[NP], and P[YP]P) and three halothane gene genotypes (NN, Nn, and nn) were tested for breed, sex, and halothane gene (HAL) effects on growth and carcass performance. Breed effects were significant for all traits measured. Sex effect was significant for most traits except for meat scores. The HAL-locus linkage group explained 20 to 30% of the total variation for meat quality scores and 1 to 10% for meat quantity and growth traits. Pietrain x Yorkshire was the fastest growing breed group and had relatively good carcass quality. Pietrain and its related crosses had the most lean muscle but the lowest meat quality. The HN (HAL negative, genotype Nn) individuals within the PPY and PNP groups grew more quickly and had higher meat quality scores and less muscling than HP (HAL positive, genotype nn) individuals. A second experiment with 40 pigs showed significant differences in fat concentration in the loin muscle between breeds (M, Y, and P) and between genotypes within the NP population (NP[HP] and NP[HN]). The phenotypic correlation between fat percentage and marbling was .59 (P less than .01). The NP(HP) had higher water percentage in lean than the NP(HN). The water percentage was negatively correlated with meat quality scores of color, firmness, and marbling with phenotypic correlations of -.10, -.23, and -.57 (P less than .01), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of the halothane gene on pork production and meat quality of pigs reared under commercial conditions

Production and meat quality traits were evaluated on 74 commercially raised heterozygous pigs (Nn) and 50 homozygous normal pigs (NN) at the halothane locus, with an average carcass weight of 79.7 kg. Eight-week weight, average daily gain and age to market, as well as measures of carcass quality (i.e., dressing percent, grade site fat and muscle depths and predicted lean yield) did not differ among pigs with Nn and NN genotypes. The longissimus dorsi muscle from Nn and NN pigs had similar subjective colour and structure scores. Reflectance meter readings (CIE L*-values) were significantly higher on chops from Nn than from NN pigs taken from the centre (57.4 vs. 55.6) and from the anterior portion (56.2 vs. 54.5) of the loin. Drip loss among Nn pigs was higher than among NN pigs for chops taken from the centre (4.8 vs. 3.8 g 100 g−1) and from the anterior portion (3.7 vs. 2.9 g 100 g−1) of the loin (P < 0.01). Soluble protein was 1.7% lower (P < 0.001) in Nn pigs compared with the NN pigs. Barrows attained market weight earlier (P < 0.05) than gilts, but they had a lower dressing percentage (P < 0.05) and greater grade fat depth (P < 0.001) and had 1.2% less predicted lean yield of carcass (P < 0.001) than gilts. Since meat quality declined without concomitant increases in growth rate or improvements in carcass quality, it was concluded that the intentional use of the halothane gene should be discouraged. Key words: Swine, production, carcass quality, meat quality, halothane gene

Halothane genotype by weight interactions on pig meat quality

The effects of slaughter weight on pork quality as influenced by halothane genotype and breed (Lacombe: LAC, NN-genotype; Yorkshire: YRK, NN-genotype) were investigated in 312 carcasses ranging in weight from less than 65 kg to greater than 105 kg. When adjusted to a warm carcass weight of 87 kg, the longissimus of LAC pigs has normal color and structure scores (2.96 and 2.99, respectively), while halothane-sensitive pigs (HSL, nn-genotype) and XBD (HSL × LAC, Nn-genotype) pigs had inferior color (2.69 and 2.83) and structure (2.55 and 2.74) scores on a 5-point scale with 3 being desirable. The results were corroborated with objective measurements of meat quality including expressible juice, drip, protein solubility and muscle color. At lighter carcass weights (65–75 kg), XBD pigs had pork quality characteristics similar to those of LAC pigs, while at heavier carcass weights (95–105 kg) pork quality from these pigs more closely resembled those of the HSL pigs. Subjective pork color and structure scoring of 85-kg YRK and LAC carcasses suggested they were normal and equivalent to each other. However, objective evaluation of pork quality found that YRK carcasses had 15 g kg −1 greater expressible juice, 8 g kg−1 greater drip and 7 g kg−1 less soluble protein than LAC carcasses, indicating meat from YRK carcasses would have lower processing yields than meat from LAC carcasses. LAC carcasses had 6 kg kg−1 greater intramuscular fat on a wet-matter basis than YRK. These results suggest that the dominance of the halothane gene as it affects pork quality may increase with increasing slaughter weight, and LAC pigs produce higher quality pork than YRK pigs. Key words: Meat quality, market weight, genotype, halothane gene, Lacombe, Yorkshire

Halothane genotype by weight interactions on lean yield from pork carcasses

Data on 42 halothane-sensitive pigs (HSL, nn-genotype), 169 Lacombe pigs (LAC, NN-genotype), 41 crossbred pigs (XBD, Nn-genotype), and 72 Yorkshire pigs (YRK, NN-genotype) representing 145 gilts and 179 castrates, were obtained over the liveweight range from 74.0 to 134.5 kg (average 105 kg) to examine the effect of genotype, gender and slaughter weight on the composition of the four lean cuts (ham, loin, picnic and butt). Gilts had a greater proportion of dissectible lean from lean cuts than castrates (557 ± 2.8 vs. 525 ± 2.6 g kg−1). The HSL pigs had the highest and LAC pigs the lowest commercial dressing percentage, increasing respectively from 85.3 to 86.0% and 79.7 kg to 82.6% as slaughter weight increased from 80 to 130 kg. Corresponding figures for XBD and YRK pigs, were 82.5 to 85.4 and 80.6 to 84.6%, respectively. Dissectible lean from lean cuts from 65-kg carcasses was 606, 525, 536 and 575 g kg−1 for HSL, XBD, LAC and YRK pigs, respectively. Corresponding figures for 85-kg and 105-kg carcasses were 574, 525, 515, and 555 g kg−1 and 542, 525, 494, and 535 g kg−1, respectively from HSL, XBD, LAC and YRK pigs. LAC and YRK pigs, each with exclusively NN-genotypes but differing in composition of lean cuts, maintained their relative differences in composition over the weight range studied. Heterogeneity of slopes for changes in proportion of lean in the lean cuts with increasing weight among the HSL, XBD and LAC pigs implied a genotype × weight interaction that could best by explained by an apparent increase in the dominance of the halothane gene with increasing carcass weight. Key words: Swine, carcass composition, halothane gene, weight, Lacombe, Yorkshire

Characterization of swine susceptible to malignant hyperthermia by in vivo, in vitro and post‐mortem techniques

We investigated German Landrace pigs from a special breeding program producing animals which were of three genotypes with respect to in vivo halothane inhalation (i.e., exposure to 3% halothane for up to 3 min): (1) Hal NN, i.e. homozygous normal exhibiting no response; (2) Hal Nn, i.e. heterozygous, also responding with a normal reaction; and (3) Hal nn, i.e. homozygous for the 'halothane gene n' which exhibited signs of malignant hyperthemia (MH). Additional characteristics of these three groups of animals were studied using accepted methodology from the fields of animal science, clinical testing, and food science. The following characteristics of group (2) and (3) were different from those of the normal animals: 1) creatine kinase levels; 2) in vitro sensitivities of muscles to caffeine and halothane administration (contracture test) and 3) postmortem muscle properties. In humans, results of the in vitro contracture test are indicative of susceptibility to MH. In humans, MH is considered to be inherited as an autosomal dominant trait. Similarly the results of the in vitro contracture test described here also indicate that MH is inherited as an autosomal dominant trait in German Landrace swine.

THE USE OF BLOOD SERUM COMPONENTS IN THE IDENTIFICATION OF STRESS-SUSCEPTIBLE AND CARRIER PIGS

A total of 284 pigs representing three genotypes were used to study the cause(s) of PSE musculature and possible means of detection of carriers of the halothane gene for stress susceptibility. The three genotypes included a homozygous halothane-sensitive line (H+), a homozygous halothane-negative line (H−) and a genetic carrier line (crossbreeds) from crosses between H+ and H− lines. A variety of blood components were determined in blood collected either from indwelling ear vein catheters on unrestrained pigs, from pigs during a halothane test or from conscious restrained pigs. Differences in levels of cortisol (P = 0.0003), creatinine (P = 0.0001), aspartate aminotransferase (AST, P = 0.0001) and lactate dehydrogenase (P = 0.0001) were highly significant between H+ and H− lines, with crossbreeds showing intermediate levels, except for AST where H− and crossbred animals had similar levels. In addition, red blood cell counts (P = 0.014) and serum protein levels (P = 0.008) were higher, and inorganic phosphorous (Pi) levels (P = 0.019) lower in H+ compared to H− and crossbred animals. Based on the results of this study, differences in the circulating levels of these metabolites, hormones or enzymes among genotypes would enable the discriminant identification of virtually all the halothane-positive pigs as well as up to 84% of the carrier animals. This approach theoretically could have a significant impact on the removal of pigs causing PSE pork.

ESTIMATION OF THE FREQUENCY OF THE HALOTHANE GENE AND ITS EFFECTS IN LANDRACE AND YORKSHIRE PIGS IN ONTARIO

Data from 2554 Landrace and 2566 Yorkshire young boars submitted to the Record of Performance test station in Ontario between 1982 and 1986 were used to estimate frequency of reaction to halothane and frequency of the halothane gene. Approximately 1.4% of Landrace and 0.9% of Yorkshire boars had a positive reaction to halothane. The number of reactors detected at the test station declined with time, particularly in the Landrace. There was evidence of the presence of the halothane gene in 25 Landrace and 25 Yorkshire breeder herds and 5.8% of Landrace and 2.8% of Yorkshire sires had progeny which tested positive. Maximum likelihood estimates of frequency of the halothane gene were 0.10 ±.02 in Landrace and 0.09 ±.02 in Yorkshire. There was only weak selection against sire lines known to have had reactor progeny. Based on estimated breeding values, sires and dams that had reactor progeny were genetically leaner than contemporaries, but there was no consistent, or significant relationship with days to 90 kg. Key words: Halothane gene, frequency, selection, swine

MUSCLE AND RECTAL TEMPERATURE RESPONSE CURVES TO A SHORT-TERM HALOTHANE CHALLENGE IN EIGHT-WEEK-OLD PIGLETS WITH KNOWN GENOTYPE AT THE HALOTHANE LOCUS

Each of the three genotypes (NN: normal, halothane negative; Nn: carrier, halothane negative; nn: halothane sensitive) at the halothane locus had a significantly different muscle temperature response curve to a 3-min halothane challenge, while only halothane positive (H+) and negative H−) phenotypes could be distinguished on the basis of the rectal temperature response curves. However, the among animal variation precludes its use as a diagnostic tool for the identification of heterozygous and homozygous normal among halothane negative pigs. Key words: Temperature, halothane gene, swine, genotype

The porcine PHIcDNA linked to the halothane gene detects a Hin dIII and Xba I RFLP in normal and malignant hyperthermia susceptible pigs

The porcine PHIcDNA linked to the halothane gene detects a Hin dIII and Xba I RFLP in normal and malignant hyperthermia susceptible pigs

The porcine PHIcDNA linked to the halothane gene detects a NotI RFLP in normal and malignant hyperthermia susceptible pigs

The porcine PHIcDNA linked to the halothane gene detects a NotI RFLP in normal and malignant hyperthermia susceptible pigs

Influence of the halothane gene and effects of halothane on the osmotic fragility of erythrocytes in pigs

ZusammenfassungDer Einfluß des Halothan‐Gens und Effekte von Halothan auf die osmotische Resistenz von Erythrozyten beim SchweinAnhand von 56 Mastschweinen der Deutschen Landrasse, die Würfen mit gleichen Anteilen MH empfindlicher und MH resistenter Tiere entstammten, wurde der direkte Einfluß des Halothan‐Gens auf die osmotische Fragilität von Erythrozyten untersucht. Außerdem wurde der Einfluß von Halothan auf die Membranen durch in‐vitro Inkubation gemessen. Die Membranen der halothanpositiven Schweine waren signifikant weniger stabil als diejenigen ihrer halothannegativen Vollgeschwister. Halothan steigerte die Membranfragilität in beiden Reaktionstypen, jedoch zu unterschiedlichen Raten und nach unterschiedlichem Muster. Die Untersuchungen sprechen für einen direkten Einfluß sowohl des Halothangens, als auch von Halothan auf die Stabilität von Erythrozytenmembranen, unabhängig von Rasseeinflüssen.

Localization on pig chromosome 6 of markers GPI, APOE, and ENO1, carried by human chromosomes 1 and 19, using in situ hybridization

In the pig, the linkage group around the halothane gene (HAL), composed of S-GPI-HAL-H-A1BG-PGD, has been assigned to bands p1.2----q2.2 of chromosome 6. In man, ENO1-PGD and APOE-GPI constitute two syntenic groups situated on different chromosomes (1 and 19, respectively). Since GPI and PGD are linked in the pig, we have hybridized the human cDNA probes for ENO1 and APOE to pig chromosomes. These markers were assigned to pig chromosome 6, in the q2.2----q2.4 and cen----q2.1 regions, respectively, using in situ hybridization. Since GPI and APOE are situated in the same region, we combined the use of high resolution chromosome analysis and in situ hybridization to give a more precise localization in the q1.2 and q1.2----q2.1.2 regions of chromosome 6. A possible linear order of these genes is proposed.

The porcine PHIcDNA linked to the halothane gene detects aNotI RFLP in normal and malignant hyperthermia susceptible pigs

The porcine PHIcDNA linked to the halothane gene detects a<i>Not</i>I RFLP in normal and malignant hyperthermia susceptible pigs

Growth and carcass performance of British Landrace pigs heterozygous at the halothane locus

ABSTRACTThe effects of the halothane gene on growth and performance were estimated from British Landrace positive and negative selection lines and crosses between the lines. A total of 214 full-sib pairs were performance tested from 25 to 85 kg live weight on either ad libitum or scale (0·69 g/g ad libitum food intake) feeding. Half-sides of 45 carcasses were fully dissected.In the crosses, growth and performance did not depend on whether the sire or the dam was from the positive line. Carcass length, conformation score, eye muscle area and incidence of pale, soft, exudative meat (PSE) were all intermediate in the crosses. Given food ad libitum, the crosses had increased appetite and growth rates which resulted in increased backfat depths. However, in the fully dissected carcasses, the crosses were intermediate for lean proportion. Although the crosses gave a net economic advantage, the incidence of PSE may be unacceptably high for commercial exploitation.

Progress on the halothane gene in pig

Progress on the halothane gene in pig