Halothane Negative Pigs Research Articles

The halothane gene, energy metabolism, adenosine monophosphate-activated protein kinase, and glycolysis in postmortem pig longissimus dorsi muscle1

The presence of the halothane gene results in PSE meat. However, the exact mechanisms linking the halothane gene and the incidence of PSE meat remain unclear. We hypothesize that the presence of the halothane gene accelerates energy consumption in postmortem muscle, which activates adenosine monophosphate-activated protein kinase (AMPK), leading to enhanced glycolysis and PSE meat. To test our hypothesis, energy status, AMPK activity, and glycolysis in the postmortem LM of the halothane gene carrier and halothane-negative pigs were compared. The results showed that the presence of the halothane gene accelerated energy depletion in postmortem muscle immediately after exsanguination, leading to rapid and early depletion of ATP, as shown by an increase in the (adenosine monophosphate + inosine monophosphate):ATP ratio in postmortem LM. In addition, an early AMPK activation was observed in LM from halothane carriers. The fructose-2,6-diphosphate concentration in postmortem LM was well correlated with AMPK activation. To be a potent stimulator of phosphofructose kinase, the increase in fructose-2,6-diphosphate is expected to activate phosphofructose kinase, a key enzyme controlling glycolysis, leading to enhanced glycolysis and early accumulation of lactic acid. In summary, this study showed that the presence of the halothane gene induced early energy depletion, which could be a primary reason causing AMPK activation, leading to accelerated glycolysis and an increased incidence of PSE meat. However, AMPK might also be activated by other mechanisms besides energy depletion, which warrants further studies.

Effects of pig age at market weight and magnesium supplementation through drinking water on pork quality1

Thirty-two halothane-negative pigs (109 +/- 0.6 kg of BW) were used to determine the effect of pig age at marketing (and thus growth rate), and magnesium supplementation through drinking water, on pork quality. Two initial groups of 50 pigs that differed by 30 +/- 2 d of age were fed diets to meet or exceed nutrient requirements beginning at 28 kg of BW. Sixteen average, representative pigs were selected from each group to represent older, slow-growing pigs and younger, fast-growing pigs. For the duration of the study, pigs were individually penned, provided 2.7 kg of feed (0.12% Mg) daily, and allowed free access to water. After 7 d of adjustment, pigs were blocked by sex and BW and allotted to 0 or 900 mg of supplemental Mg/L as MgSO4 in drinking water for 2 d before slaughter. All 32 pigs were then transported (110 km) to a commercial abattoir on the same day and slaughtered 2.5 h after arrival. Longissimus and semimembranosus (SM) chops were packaged and stored to simulate display storage for fluid loss and Minolta color determinations at 0, 2, 4, 6, and 8 d. Two remaining sections of the LM were vacuum-packaged and stored at 4 degrees C for 25 or 50 d. Fast- (younger) and slow- (older) growing pigs differed by 27 +/- 0.3 d of age (153 and 180 +/- 0.3 d; P < 0.001) at similar BW (108 and 110 +/- 0.6 kg of BW; P = 0.13). Supplementation of Mg tended to increase plasma Mg concentration (24.1 vs. 21.8 +/- 0.8 ppm; P = 0.06) but did not affect Mg concentration in LM or SM. Fluid loss of displayed LM or SM, and purge loss, color, and oxidation of vacuum-packaged LM or SM were not affected by age or Mg (P > 0.10). Surface exudate of the SM from older pigs was lower than that of younger pigs (61 vs. 74 +/- 6 mg; P = 0.05) but was not different for the LM (P = 0.22). The LM from older pigs displayed for 4 and 8 d; P < 0.05) were less yellow (lower b*) than younger pigs. The SM from older pigs had lower lightness (L*) initially (47.9 vs. 49.5 +/- 0.4) and after 2 d (49.7 vs. 51.1 +/- 0.4), 6 d (52.1 vs. 53.7 +/- 0.4) and 8 d (54.5 vs. 55.9 +/- 0.4) of display storage. Younger pigs had greater oxidation of the LM than older pigs on d 8 of display (P < 0.01), and Mg decreased oxidation on d 8 within younger pigs (P < 0.05). Pork quality was improved in older pigs as indicated by less exudate, reduced yellowness of the LM, reduced paleness of the SM, and reduced oxidation of the LM. However, Mg supplementation through the water for 2 d did not affect pork quality of either older, slower growing pigs or younger, faster growing pigs.

The preference of the consumer for pork from homozygous or heterozygous halothane negative animals

To evaluate the taste preference of the consumer for meat from homozygous (NN) halothane negative pigs or heterozygous (Nn) halothane negative pigs, a consumer test was conducted at the “Agriflora” exhibition, concerning Flemish agriculture and horticulture, held from 8 to 10 January 1999 in Ghent, Belgium. The carcass quality of both tested genotypes was similar, while acidity, colour and drip loss were inferior and cooking loss and Warner-Bratzler shear force superior for the Nn pigs compared with the NN pigs. One hundred and seventy-one visitors completed the test correctly. No significant difference was found between NN- and Nn-meat for the tastiness scores. These results do suggest that elimination of the halothane gene from the pig population does not guarantee a better eating quality of the meat.

Development of pale, soft, exudative pork in halothane-negative pigs through post-mortem infusion

A single-limb infusion of post-mortem muscle was used to determine the effect of calcium salts and calcium chelators on post-mortem metabolism and meat quality. Regardless of the type of infusate, the infusion process itself resulted in an acceleration of glycolysis, increased drip loss, paler meat colour (shifts in L* and hue angle) and decreased shear. The observed tenderization as a result of these infusions sheds some doubt that the calpain enzyme system is solely responsible for post-mortem tenderization. Key words: Pork; pale, soft, exudative; single-limb infusion; tenderization

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.

Effect of oral loading of acid or base on the incidence of pale soft exudative pork (PSE) in stress-susceptible pigs

Thirty-three halothane-positive pigs were assigned to one of three ad libitum water treatments 4 days prior to slaughter: control, sodium bicarbonate (12·6 g litre −1), or ammonium chloride (8 g litre −1) to study the effect of an oral acid or base load on post-mortem changes in the longissimus dorsi muscle and on ultimate pork quality. Eight halothane-negative pigs were also slaughtered as negative controls. Dietary ammonium chloride caused a metabolic acidosis as indicated by lower blood and urine pH, and lower blood bicarbonate in treated pigs. In halothane-positive pigs, dietary treatments had no significant effect on post-mortem muscle pH changes or on measurements of muscle quality (colour, drip loss, texture scores or protein solubility). There was a weak to modest relationship between the blood gas measurements and meat quality indicators. Blood pH ( r = 0·566) and bicarbonate ( r = 0·514) were positively correlated with subjective texture scores and a trend was seen for blood PCO 2 and bicarbonate to be positively related to 45 min pH and subjective colour. These observations suggest that pigs with increased blood pH and bicarbonate may show an improvement in meat quality. Further research is necessary to find the optimum time and level of treatment to maximize the response.

Acid Base Status of Stress Susceptible Pigs Affects Sensory Quality of Loin Roasts

ABSTRACTHalothane positive pigs (24) were placed on water treatments containing sodium bicarbonate (BC, 12.6 g/L), ammonium chloride (AC, 8 g/L) or no additive for 4 days and slaughtered. Halothane negative pigs (8) also were slaughtered. Loin roasts were aged for periods of 1 or 7 days. Loin roasts from animals treated with AC were scored (P&lt;0.05) less firm, juicy, more tender and mealy than roasts from other halothane positive and halothane negative animals. No difference in sensory properties occurred with aging. Juiciness and off‐flavor intensity were positively related to blood bicarbonate and base excess.

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 m m 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.

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

Phosphorus nuclear magnetic resonance ( 31P 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. 31P 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.

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

Halothane-sensitivity gene and muscle contractile properties in malignant hyperthermia.

Malignant hyperthermia (MH) results from the presence of the halothane-sensitivity gene and is characterized by abnormalities in muscle function. Populations of genetically defined pigs were used to determine the in vivo and in vitro expression of this gene in both the homozygous and the heterozygous condition. On exposure to halothane, isolated muscle bundles from the homozygous halothane-sensitive pigs exhibited decreased tetanus tension and increased tetanus half-relaxation time and contracture and were clearly distinguished from homozygous normal muscles. The heterozygous and homozygous normal muscles were similar in contractile responses except for the occurrence of halothane-induced contractures in the heterozygotes. The heterozygous halothane-negative pigs did not exhibit the characteristic signs of an MH episode in response to halothane succinylcholine, although some metabolic responses were significantly altered (e.g., increased venous partial pressure of CO2 and arterial and venous K+ concentration). Thus the heterozygous pigs were not MH susceptible but did represent a phenotype distinct from the homozygous normal pigs both in vitro and in vivo. These data provide the first convincing evidence for the expression of the halothane-sensitivity gene in heterozygotes.

Behaviour in pigs from three genotypes segregating at the halothane locus

The intention of the present study was to identify unique behaviour traits in halothane-positive pigs, as well as crossbred carriers of the halothane gene, compared to halothane-negative pigs. The identification of such traits may be useful in forming guidelines for management and environment changes aimed at improving pork quality. Twenty-four-hour VHS time-lapse recordings were collected on 16 halothane-negative pigs (H −; NN genotype), 16 halothane-positive pigs (H +; nn genotype) and 16 pigs which were the F 1 progeny of H +×H − (H +−; Nn genotype). Ethograms constructed from these tapes revealed that H + pigs drank and ate less frequently than H − or H +− pigs and were also more active with respect to pen investigative behaviour ( P≤0.01). Halothane-positive pigs also slept more frequently in groups and displayed fewer total aggressive acts than the other two genotypes ( P≤0.01). Both H + and H +− pigs displayed comparatively greater levels of neutral/non-aggressive acts, including nose-nose and nose-body contact ( P≤0.01). However, when subjected to either 24 or 48 h off feed, all genotypes behaved in a similar manner, generally reducing the level of activity in most behaviour traits. The results of the present study suggest that genotype differences in behaviour among these three genotypes do exist.

The effect of electrical stimulation, time of boning and high temperature conditioning on sensory quality traits of porcine Longissimus dorsi muscle

The effects of electrical stimulation (300 V, 1 A, 50 Hz, AC, 30 s) and high temperature conditioning (4h/15°C) on sensory quality traits of hot- and cold-boned, vacuum-packaged longissimus dorsi muscle of halothanenegative pigs were assessed at 12 days post mortem. Electrical stimulation accelerated the pH fall significantly, but had negligible effects on all quality traits measured, i.e. shear force, drip formation, fresh meat colour, cooking loss and degree of sarcoplasmic protein denaturation (p > 0·05). As compared with cold boning, hot boning significantly lowered drip losses (p < 0·05). Shear forces, which increased as a result of hot boning (p < 0·05), were reduced again through a 4 h/15°C conditioning period before chilling at 1 ±1°C. In addition, high temperature conditioning resulted in significantly lower drip losses (p < 0·05). It is suggested that prevention of cold-induced reduction of proteolytic enzyme activity is primarily responsible for both these findings.

The effects of Sarcocystis miescheriana infections on blood enzymes and weight gain of stress-sensitive and stress-insensitive pigs

The effects of mild Sarcocystis miescheriana infection on blood enzymes and body weight were compared in stress-sensitive (halothane positive) and in stress-insensitive (halothane negative) pigs. Ten halothane-positive pigs (Group A) and ten halothane-negative pigs (Group C) with a mean body weight of 36 kg were each inoculated orally with 50 000 sporocysts of S. miescheriana. Twelve halothane-positive pigs (Group B) and ten halothane-negative pigs (Group D) served as non-infected controls. Five days before infection (a.i.) and 58 days post infection (p.i.) all pigs were myostress challenged (creatine kinase test). During the whole period of the experiment (3 weeks a.i. to 13 weeks p.i.) body weights were determined and blood samples taken at weekly intervals. Creatine kinase (CK), aspartate aminotransferase (ASAT) and Sarcocystis antibody titres were determined. The infection induced slighly elevated temperatures (max. 42.8°C) and transient reduced food intake during the 2nd and 3rd week p.i. The CK values of the infected pigs in Groups A and C increased from Day 28 p.i. onwards, and were significantly higher than those of the pigs of the non-infected controls (Days 35–77 p.i.). The ASAT values of the infected groups (A and C) increased from Day 21 p.i. onwards, and were significantly higher than those of the non-infected controls from Days 28–77 p.i. The myostress injection at 5 days a.i. (1st CK test) resulted in significantly higher CK and ASAT values in stress-sensitive pigs. The myostress injection at 58 days p.i. (2nd CK test) induced significantly increased plasma enzyme activities in the infected pigs of both the halothane-positive and halothane-negative groups. The mean body weight of the infected pigs was significantly lower than of the non-infected controls (Days 42–84 p.i.).

Effects of Sarcocystis miescheriana infection on carcass quality and on the water-binding capacity of the meat of halothane-tested fattening pigs

Ten halothane-positive pigs (stress sensitive, group A) and ten halothane-negative pigs (stress insensitive, Group C) with a mean body weight of 36 kg were each inoculated orally with 50 000 sporocysts of Sarcocystis meischeriana. Twelve halothane-positive pigs (Group B) and ten halothane-negative pigs (Group D) served as non-infected controls. Thirteen weeks post infection (p.i.) the lean:fat ratios of the pigs of the infected groups A and C were lower (A 1:041 ± 0.09; C, 1:0.50 ± 0.10) than those of the pigs non-infected groups B and D B, 1:0.50 ± 0.08; D, 1:0.55 ± 0.08). The back-fat thickness, the fat thickness ‘A’ and the fat thickness ‘B’ were thinner in infected pigs than in non-infected pigs. The difference in Lendenstärkespeckquotient (Loin Fat Thickness Quotient) (LSQ) between infected and non-infected pigs was not statistically significant. The values of the water-holding capacity were lower in infected pigs than in non-infected pigs, the difference being statistically significant only in the halothane-negative groups (C, 0.45 ± 0.02; D, 0.48 ± 0.04). The water-absorbing capacity was significantly higher in the infected groups (A, 5.92 ± 0.02; B, 2/26 ± 3/99%; C, 8.96 ± 2.90%; D, 4.97 ± 2.51%). In conclusion, it can be said that there was a slight tendency towards a better carcass quality and a better water-binding capacity in infected pigs, although this was combined with reduced growth rates.

Fibre optic probe measurements in landrace pigs of different halothane phenotypes

Fibre Optic Probe (FOP) measurements were made in the longissimus dorsi muscle of 70 halothane-positive (HP) and 70 halothane negative (HN) pigs of a synthetic Landrace strain at 45 min (FOP 1), 3 h (FOP 3) and 17h (FOP 17) post mortem. Measurements of pH, rigor and temperature were also made in the slaughterline. Carcasses were sampled ( longissimus dorsi, 2–4 lumbar vertebrae) at 18h post mortem and meat quality objectively assessed. The incidence of slight PSE (visual score) was 49% in HP and 10% in HN pigs, while the incidence of serious PSE was 20% and 4%, respectively. Yet, the percentage drip loss during 48 h storage in HN/PSE pigs was higher than in HP/PSE pigs (10·2 vs 7·5%), which was associated with a lower ultimate pH (5·25 vs 5·44). Therefore, it is suggested that the remaining PSE problem in HN Landrace pigs, although less in frequency, might be more serious. In the whole population, of all FOP measurements taken correlations with colour (Hunter L ∗-value) and percentage drip loss were highest for the FOP 17 measurements ( r = 0·82 and 0·69, respectively). FOP 1 was better related than pH 1 to colour, while the relationships with drip loss were of a similar magnitude. Differences in FOP values between HP and HN pigs were larger for FOP 1 (148 vs 108) than for FOP 3 (148 vs 125) or FOP 17 (153 vs 130). The relationship between FOP1 and ultimate meat colour ( L ∗-value) appeared to be higher in HP (0·60) than in HN (0·48) pigs, while for the relationship between FOP 1 and percentage drip loss the reverse was true (0·48 and 0·60, respectively). The effect of halothane phenotype on the relationships found, may partially explain the different results of reflectance measurements reported in the literature as to their predictive value for ultimate meat quality. The results suggest that the measurement of reflectance in the slaughterline offers opportunities for identifying (potential) PSE carcasses. The large genetic influence of halothane phenotype on this parameter, may eventually justify its use as a base for payment for meat quality to the producer.

Effects of Sarcocystis miescheriana infection on carcass weight and meat quality of halothane-tested fattening pigs

Ten halothane-positive pigs (Group A) and ten halothane-negative pigs (Group C) were each infected per os by 50 000 sporocysts of Sarcocystis miescheriana when they had reached a mean body weight of 36 kg. Twelve halothene-positive pigs (Group B) and ten halothane-negative pigs (Group D) served as non-infected controls. Thirteen weeks p.i. (post infection), the pigs were slaughtered and the carcass weights and the number of cystozoites in several muscles were determined. In addition, 11 parameters of meat quality were measured in Musculus longissimus dorsi (M.l.d.) and Musculus semimembranosus (M.s.): pH and temperature 30 min and 24 h p.m. (post mortem), electrical conductance 45 min, 60 min and 24 h p.m., colour brightness (FOP) and rigor values 30 min and 24 h p.m. Additionally, the AMP, ADP, ATP and lactate contents were determined in samples from the M.l.d. The mean carcass weights of the infected pigs (A: 79.9 ± 6.9 kg; C: 76.3 ± 11.6 kg) were lower than those of the pigs of the non-infected groups (B: 85.7 ± 8.0 kg; D: 87.5 ± 7.0 kg). The pH values at 24 h p.m. were significantly higher in the M.l.d. of infected pigs than in M.l.d. of non-infected pigs. Electrical conductance in the M.s. at 45 min p.m. was significantly higher in the halothane-negative infected pigs, but at 24 h p.m., the mean values of electrical conductance in the M.s. of the pigs of both infected groups were significantly lower than in the control groups. FOP values at 30 min p.m. were raised in the M.l.d. of the halothene-negative infected pigs, but at 24 h p.m., differences between infected and non-infected pigs could no longer be found. Mean rigor values were higher in the pigs of the infected groups at 24 h p.m., but the difference from the non-infected groups was not statistically significant. AMP was reduced only in the meat of halothane-positive infected pigs, while lactate was reduced in both infected groups. Using conventional methods for the determination of meat quality, the hypothesis of impaired meat quality in Sarcocytis-infected pigs could not be confirmed. The meat quality parameters investigated were, in part, better in infected pigs than in non-infected controls.

Carcass characteristics and meat quality of halothane negative and halothane positive pietrain pigs

One hundred and seventy-six Pietrain pigs were tested for halothane sensitivity by means of a 5-min halothane anaesthesia in two experiments. One hundred and twenty were halothane negative (HN) and 56 were halothane positive (HP). In one experiment pigs were slaughtered under commercial (stress) conditions; in the other experiment pigs were killed under minimal stress conditions. The carcasses of HP pigs were meatier and shorter and contained 2·2% more muscle than the carcasses of HN pigs. Halothane positive pigs gave a meat of poorer quality, as assessed in the fresh state. When the pigs were slaughtered under commercial conditions, hams from HP pigs were not inferior in curing ability and had a higher total processing yield of Paris ham due to their higher trimming yield. When the pigs were killed under minimal stress conditions, there was no difference in the total processing yield betwen HN and HP pigs, because the technological yield was markedly reduced in HP pigs. However, in both cases, HP pigs produced more cooked ham per pig. It is suggested that different physiological mechanisms may account for either PSE (pale soft exudative) or DFD (dark firm dry) meat. The former is the consequence of an excessively high rate of post mortem glycolysis which is clearly manifest in HP pigs when they are killed under minimal stress conditions and the latter appears to be unrelated to halothane sensitivity as the ultimate pH of HP and HN pigs is similar when the animals are slaughtered under stress conditions.

The physiological reaction of halothane tested pigs to treadmill exercise, and to slaughter

Two groups of pigs, 13 halothane positive and 16 halothane negative, were compared after treadmill exercise. Blood samples were collected by means of chronic indwelling catheters and analysed for LDH, CK, LDH-isoenzymes and cortisol. The basal values under rest conditions were higher in halothane positive pigs.Up to 5 hours after treatment, the difference in values between halothane positive and halothane negative pigs increased, indicating a low ability of halothane positive animals to adapt to environmental stress. Carcass composition was better in halothane positive, while meat quality was better in halothane negative pigs.