Halothane Gene Research Articles

Meta-analysis of the halothane gene effect on parameters of pig meat quality

Technological meat quality has a significant economic impact and many publications have shown that pig meat quality is strongly influenced by the effect of genetic type (especially Hal and RN genes) and by rearing and slaughter conditions (Sellier and Monin, 1994). The quality of meat is generally assessed by measuring meat pH at different times post mortem, colour or drip loss. Our study consists on a meta-analysis based on 11 publications in order to assess the possibility of predicting the effects of halothane gene, sex, breed and slaughter weight of animals on three selected parameters: pH at 45 minutes post mortem (pH45), ultimate pH (pHu) and reflectance (L*-value).

Effect of the duration of commercial journeys between rearing farms and growing–finishing farms on the physiological stress response of weaned piglets

To find the effect of journey duration on the stress levels of weaned piglets a combination of physiological welfare indicators was used. One hundred and thirty-six piglets were monitored in two replicates of a short (0.6 h) and a long (8.3 h) commercial transport from a rearing to a growing–finishing farm. Variables studied were haematocrit, red blood cell count (RBC), total white blood cell count (WBC), differential WBC counts, serum pig's major acute phase protein (Pig-MAP), haptoglobin (Hp), cortisol, glucose, creatine phosphokinase (CPK), lactate dehydrogenase (LDH), total protein, and albumin before loading and immediately after unloading. A marked increase in leucocytes ( P < 0.01) and a tendency to lower eosinophil concentrations ( P = 0.086) were observed in those piglets transported during the short journeys. On the other hand, the decrease in lymphocytes was particularly remarkable in the long journeys ( P < 0.01). No increase in Hp concentrations after the transports was found, but an increase in Pig-MAP concentrations was observed at the end of the long journeys ( P < 0.001). Cortisol concentrations did not show significant changes in either short or long journeys. According to CPK ( P < 0.05) and LDH activities, some physical fatigue was detected at the end of transports, particularly in the short journeys. The decrease in haematocrit values in the short journeys ( P < 0.05), and the absence of variations in RBC, albumin, and total protein concentrations would indicate that the loss of body water during both transport durations was reduced. Sex did not affect the response of piglets to transport, which could be attributable to the young age of the animals. Changes in albumin concentrations ( P < 0.05), together with the tendencies to higher WBC ( P = 0.092) and neutrophil counts ( P = 0.076), suggest a more marked response to the stress of transport in heterozygous for the halothane gene ( Nn) piglets than in homozygous negative ( NN) piglets. Overall results indicate that, although transports were generally stressful, it is unclear which of the two durations was more detrimental for piglet welfare, and suggest a different stress response to transport with respect to that of older pigs.

Myosin heavy chain isoform content and energy metabolism can be uncoupled in pig skeletal muscle

Genetic selection for improved growth and overall meatiness has resulted in the occurrence of 2 major mutations in pigs, the Rendement Napole (RN) and Halothane (Hal) gene mutations. At the tissue level, these mutations influence energy metabolism in skeletal muscle and muscle fiber type composition, yet also influence total body composition. The RN mutation affects the adenosine monophosphate-activated protein kinase gamma subunit and results in increased glycogen deposition in the muscle, whereas the Hal mutation alters sarcoplasmic calcium release mechanisms and results in altered energy metabolism. From a meat quality standpoint, these mutations independently influence the extent and rate of muscle energy metabolism postmortem, respectively. Even though these mutations alter overall muscle energy metabolism and histochemically derived muscle fiber type independently, their effects have not been yet fully elucidated in respect to myosin heavy chain (MyHC) isoform content and those enzymes responsible for defining energetics of the tissue. Therefore, the objective of this study was to determine the collective effects of the RN and Hal genes on genes and gene products associated with different muscle fiber types in pig skeletal muscle. To overcome potential pitfalls associated with traditional muscle fiber typing, real-time PCR, gel electrophoresis, and Western blotting were used to evaluate MyHC composition and several energy-related gene expressions in muscles from wild-type, RN, Hal, and Hal-RN mutant pigs. The MyHC mRNA levels displayed sequential transitions from IIb to IIx and IIa in pigs bearing the RN mutation. In addition, our results showed MyHC protein isoform abundance is correlated with mRNA level supporting the hypothesis that MyHC genes are transcriptionally controlled. However, transcript abundance of genes involved in energy metabolism, including lactate dehydrogenase, citrate synthase, glycogen synthase, and peroxisome proliferator-activated receptor alpha, was not different between genotypes. These data show that the RN and Hal gene mutations alter muscle fiber type composition and suggest that muscle fiber energy metabolism and speed of contraction, the 2 determinants of muscle fiber type, can be uncoupled.

An Improved Method for Quantitative Trait Loci Detection and Identification of Within-Line Segregation in F2 Intercross Designs

We present a new flexible, simple, and powerful genome-scan method (flexible intercross analysis, FIA) for detecting quantitative trait loci (QTL) in experimental line crosses. The method is based on a pure random-effects model that simultaneously models between- and within-line QTL variation for single as well as epistatic QTL. It utilizes the score statistic and thereby facilitates computationally efficient significance testing based on empirical significance thresholds obtained by means of permutations. The properties of the method are explored using simulations and analyses of experimental data. The simulations showed that the power of FIA was as good as, or better than, Haley-Knott regression and that FIA was rather insensitive to the level of allelic fixation in the founders, especially for pedigrees with few founders. A chromosome scan was conducted for a meat quality trait in an F(2) intercross in pigs where a mutation in the halothane (Ryanodine receptor, RYR1) gene with a large effect on meat quality was known to segregate in one founder line. FIA obtained significant support for the halothane-associated QTL and identified the base generation allele with the mutated allele. A genome scan was also performed in a previously analyzed chicken F(2) intercross. In the chicken intercross analysis, four previously detected QTL were confirmed at a 5% genomewide significance level, and FIA gave strong evidence (P < 0.01) for two of these QTL to be segregating within the founder lines. FIA was also extended to account for epistasis and using simulations we show that the method provides good estimates of epistatic QTL variance even for segregating QTL. Extensions of FIA and its applications on other intercross populations including backcrosses, advanced intercross lines, and heterogeneous stocks are also discussed.

Causes of pre-slaughter mortality in Danish slaughter pigs with special emphasis on transport

AbstractAnnual statistics for transport and lairage mortality were used to investigate factors leading to pre-slaughter mortality in Danish pigs. A subset of material from 2002, amounting to 17.8 million pigs, was used for a more detailed study of the effect of producer, haulier, abattoir and transport distance (&lt; 100, 100–200 and &gt; 200 km) on transport mortality. Total mortality was reduced eight-fold during the period that the halothane gene was being removed from the pig population, from 0.12% in the early 1980s to 0.016% in 2002. Overall, transport mortality increased with higher temperature and lower relative humidity/wind speed but a combination of temperature and humidity that fell into the danger zone, as defined by the Livestock Weather Safety Index, almost doubled transport mortality from a level of about 0.016 to 0.031%. Multiple deaths on the same transport were also more frequent during the hotter months of the year. Transport mortality increased with increasing transport distance, especially during warmer weather. Producers, hauliers and abattoirs had widely varying transport mortality. Eighty-nine percent of producers, 11% of hauliers and 86% of farmer transports had no mortality at all. Producers and farmer transports supplying less than 1,000 pigs had a higher transport mortality than those supplying more pigs, whereas it was independent of supply for hauliers. There were many confounding factors in this work, as producers, hauliers and abattoirs are linked and trends over the years can be affected not only by changes in the genetic makeup of the pig population but also by improvements in handling. Nevertheless, the study shows that internal environment within the vehicle and transport pattern, including the time the vehicle is stationary, are important factors for mortality and that particular efforts should be made if weather forecasts predict dangerous combinations of temperature and humidity. It is suggested that efforts to further reduce transport mortality in Danish pigs should concentrate especially on these factors and include a routine follow-up of all multiple deaths to pinpoint specific factors leading to mortality.

Serum stress parameters in pigs transported to slaughter under commercial conditions in different seasons

To determine the influence of slaughter transports carried out under commercial conditions, 162 pigs weighing 98 kg and of both sexes were studied. A total of seven transports were performed in summer and in winter conditions, with durations of 1 h and 13 h 15 min within each season. Cortisol, glucose, creatine phosphokinase (CPK), lactate dehydrogenase (LDH), albumin and total protein serum concentrations were measured. All variables increased during transport and decreased during lairage (&lt;i&gt;P&lt;/i&gt; &lt; 0.001), with cortisol values being 3.47 ± 0.19, 8.52 ± 0.28, and 6.96 ± 0.18 µg/dl at loading, unloading and exsanguinations, respectively, except for glucose (0.54 ± 0.03, 0.44 ± 0.04, and 0.86 ± 0.03 g/l). Short journeys did not allow the total recovery from the loading stress. A certain level of dehydration was observed, especially during lairage on the longest journeys (increase of 6.87 ± 1.29 g/l for total proteins; &lt;i&gt;P&lt;/i&gt; &lt; 0.01). Winter transports were slightly more stressful (&lt;i&gt;P&lt;/i&gt; &lt; 0.01 for cortisol and LDH, and &lt;i&gt;P&lt;/i&gt; &lt; 0.001 for CPK), with poorer recovery during lairage (CPK decrease being –141 ± 559 and –2 906 ± 730 IU/l for winter and summer journeys, respectively; &lt;i&gt;P&lt;/i&gt; &lt; 0.01). Females showed higher stress reactivity. Genetics modulated the effect of the rest of influencing factors, with Nn individuals showing a rougher reaction in short and winter conditions, but with lower dehydration levels. Under Mediterranean commercial conditions, stress in transported slaughter pigs was largely determined by season and genetics, so that an adaptation of handling procedures to these seasonal variations appears crucial if transport stress is to be reduced. Also, an improvement in stress resistance could be obtained by controlling the halothane gene of pigs.

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.

Head current during and blood splashes after electrical stunning in relation to characteristics of the pig’s body

In order to evaluate electrical stunning in relation to the incidence of blood splashes, meat quality and carcass quality parameters, 2035 pigs, heterozygous for the halothane gene, were observed during slaughter at a commercial slaughterhouse. The head current during electrical stunning is significantly higher ( P < 0.01) in gilts with a lower live weight ( P < 0.0001) or cold carcass weight ( P < 0.0001) and a higher lean meat percentage ( P < 0.0001). Also the incidence of blood splashes in the ham is significantly higher in gilts ( P < 0.0001) with a higher lean meat percentage ( P = 0.0028; odds ratio = 1.11), a lower live weight ( P = 0.003; odds ratio = 0.98) and a lower type number ( P = 0.0074; odds ratio = 0.64). For barrows, no significant parameters were revealed. These results suggest that the variability in incidence of blood splashes can be explained by the variability of current density depending both on sex and body characteristics. Thus, electrical stunning can be improved by providing an energy level, based on the body characteristics of the pig.

Effects of dietary magnesium and short-duration transportation on stress response, postmortem muscle metabolism, and meat quality of finishing swine1

Crossbred pigs, heterozygous for the halothane gene, were used to determine the effects of long-term dietary supplementation of magnesium mica (MM) and short-duration transportation stress on performance, stress response, postmortem metabolism, and pork quality. Pigs were blocked by weight, penned in groups (six pigs per pen), and pens (three pens per diet) were assigned randomly either to a control corn-soybean meal diet or the control diet supplemented with 2.5% MM (as-fed basis; supplemented at the expense of corn). Diets were fed during the early-finisher (0.95% lysine, as-fed basis; 43.7 to 68 kg) and late-finisher (0.85% lysine, as-fed basis; 68 to 103 kg) periods. At the conclusion of the 71-d feeding trial, 12 pigs from each dietary treatment were selected randomly and subjected either to no stress (NS) or 3 h of transportation stress (TS). Dietary MM had no effect (P > or = 0.40) on ADG or ADFI; however, G:F was improved (P < 0.05) during the early-finisher period when pigs were fed MM-supplemented diets. Plasma glucose concentrations were increased in TS pigs fed the control diet, but transportation did not affect plasma glucose in pigs fed 2.5% MM (diet x transportation stress; P = 0.02). Dietary MM did not affect blood lactate, cortisol, insulin, NEFA, Ca, or Mg concentrations in response to TS (diet x transportation stress; P > or = 0.13); however, circulating lactate, cortisol, and glucose concentrations increased in TS pigs (transportation stress x time; P < 0.01). The LM from TS pigs fed MM had higher initial (0-min) and 45-min pH values than the LM from NS pigs fed the control diet (diet x transportation stress x time; P = 0.07). Lactic acid concentration and glycolytic potential were greater in the LM of TS pigs fed MM than TS pigs fed control diets (diet x transportation stress; P < or = 0.01). Although some trends were identified, neither MM (P > or = 0.15) nor TS (P > or = 0.11) altered the color or water-holding capacity of the LM and semimembranosus. The transportation model elicited the expected changes in endocrine and blood metabolites, but dietary MM did not alter the stress response in pigs. Conversely, although pork quality traits were not improved by dietary MM, delaying postmortem glycolysis and elevating 0- and 45-min muscle pH by feeding finishing diets fortified with MM may benefit the pork industry by decreasing the incidence of PSE pork in pigs subjected to short-duration, routine stressors.

Influence of transport stress on serum cortisol and thyroid hormones in pigs with Halothane gene

ABSTRACTThe influence of transport stress on rectal temperature, respiratory rate and serum concentrations of cortisol, thyroxine and triiodothyronine (T3) in normal pigs (NN) and in heterozygous (Nn) pigs with Halothane gene (n), a major gene that causes the pale, soft, exudative meat (PSE), were examined in a hot environment (32–34°C). Easily releasable myofilament content of Longissimus dorsi taken by needle biopsy was also measured as an index of myofibrillar disassembly. Rectal temperature and respiratory rate were significantly increased by the transport. However, the influence was higher (P &lt; 0.01) in Nn pigs. Serum concentration of cortisol was increased (P &lt; 0.01) by the transport despite the genotypes. Serum concentration of T3 was not changed by the transport in Nn pigs, whereas in NN pigs it was significantly decreased after the transport (P &lt; 0.01). Easily releasable myofilament content after the transport was higher in Nn pigs than that of NN pigs (P &lt; 0.05). These results suggest that response of thyroid function might relate to the stimulation of muscle proteolysis and PSE in Nn pigs under stressful conditions.

Efeito do genótipo halotano e de diferentes sistemas de produção na qualidade da carne suína

Verificou-se o efeito dos genótipos halotano homozigoto dominante e heterozigoto e dos sistemas de criação confinado sobre piso de cimento, confinado sobre cama de maravalha e ao ar livre sobre a qualidade da carne suína. Foram utilizados 96 suínos machos castrados selecionados através do exame de DNA genômico, utilizando-se a técnica de reação em cadeia de polimerase (PCR) para amplificar a região do receptor rianodina. A região amplificada foi clivada pela técnica polimorfismo do comprimento dos fragmentos de restrição (RFLP). Mediu-se o pH nos músculos Longissimus dorsi e Semimembranosus aos quarenta e cinco minutos e vinte e quatro horas após o abate. A capacidade de retenção de água foi avaliada em amostras do músculo Longissimus dorsi através das técnicas de perda de líquido por gotejamento, de cocção e de descongelamento. Escores para a cor e o grau de marmorização da carne foram atribuídos com auxílio de padrões fotográficos. A maciez da carne foi medida pela força de cisalhamento em equipamento Warner-Bratzler Shear. Suínos com gene halotano heterozigotos apresentaram valores inferiores de pH, menor capacidade de retenção de água e uma freqüência de carcaças com carne PSE três vezes maior. O sistema de criação não afetou os valores de pH inicial e final ou a capacidade de retenção de água da carne suína. A maior incidência de carne PSE foi observada nas carcaças dos suínos criados em sistema confinado sobre piso de concreto. Não houve efeito significativo da interação genótipo halotano e sistema de criação para as características avaliadas.

Effect of Transport Stress on Serum Haptoglobin and Pig-Map in Pigs

AbstractThis study was undertaken in order to determine the variation of the acute phase proteins haptoglobin and Pig-MAP (major acute phase protein) in the serum of pigs affected by transport-related stress. Pigs were subjected to one of two pre-slaughter treatments: a) short-duration transport (1 h 15 min transport and 2 h lairage); or b) long-duration transport (6 h transport and 14 h lairage). There were 10 individuals in each treatment group, belonging to the NN (n = 5) or Nn (n = 5) genotypes for halothane susceptibility. Samples were taken before transport, just after transport, and on stunning at slaughter. We measured levels of serum haptoglobin, Pig-MAP and cortisol. Our results showed that the short-duration transport did not modify the levels of haptoglobin or of Pig-MAP in any of the three samples, whereas cortisol was increased just after transport. In contrast, there was an increase in haptoglobin and Pig-MAP in serum from animals after long-duration transport, as observed in the post-mortem samples (20-21 h after the beginning of transport); cortisol levels were not increased in these conditions. In this experiment, homozygotes for the halothane gene tended to have higher values of haptoglobin after slaughter than did heterozygotes. In conclusion, combined determination of acute phase proteins and cortisol levels could provide valuable information on welfare problems related to transport.

Efeito do genótipo halotano e de diferentes sistemas de produção no desempenho produtivo e na qualidade da carcaça suína

O objetivo deste trabalho foi verificar o efeito dos genótipos halotano homozigoto dominante e heterozigoto e de três sistemas de criação (confinado sobre piso de cimento, confinado sobre cama de maravalha e ao ar livre) no desempenho produtivo e na qualidade da carcaça e da carne suína. Foram utilizados 96 suínos machos castrados selecionados pelo exame de DNA genômico no sangue utilizando-se a técnica de reação em cadeia da polimerase (PCR) para amplificar a região do receptor rianodina. A região amplificada foi clivada pela técnica do polimorfismo do comprimento dos fragmentos de restrição (RFLP). Nas fases de crescimento e terminação, avaliaram-se ganho de peso, consumo de ração e conversão alimentar. Após o abate, as carcaças foram pesadas e tipificadas eletronicamente. Vinte e quatro horas após o abate, foram separados e pesados o pernil e o carrê e medida a área de olho de lombo. A presença do gene halotano não afetou o desempenho dos suínos, mas aumentou a porcentagem de carne magra e diminuiu a quantidade de gordura na carcaça. Suínos criados no sistema intensivo ao ar livre apresentaram menor ganho de peso e pior conversão alimentar. No sistema intensivo de criação confinado sobre cama, os suínos produziram carcaças com menor quantidade de carne magra e maior quantidade de gordura. Não houve efeito significativo da interação genótipo halotano e sistema de criação para as características avaliadas.

Effect of stun duration and current level applied during head to back and head only electrical stunning of pigs on pork quality compared with pigs stunned with CO 2

The effect of current, duration and method of application of manual electrical stunning on pork carcass and meat quality attributes in comparison with stunning pigs with CO 2 was investigated. Two experiments were conducted using a total of 96 Large White×Landrace boars (homozygous dominant for the halothane gene). In Experiment 1, 48 pigs were allocated to one of six stunning treatments: CO 2 (90% in air), electrical stunning (ES) using head only (HO) tongs delivering current at a frequency of 50 Hz at 1.3 or 2.0 A for 4 s and 0.9, 1.3 or 2.0 A for 19 s. Higher drip loss occurred in M. longissimus thoracis et lumborum (LTL) muscles from ES pigs, except those stunned with 0.9 A for 19 s, compared with pigs stunned with CO 2. The incidence of pale, soft exudative (PSE) meat was higher in ES pigs, except those stunned at 1.3 A for 4 s, compared with CO 2 stunned pigs. In Experiment 2, 48 pigs were allocated to one of six stunning treatments: ES using a head to back (HB) handpiece delivering current at 1.3 or 2.0 A for 4 s and 0.9 or 1.3 A for 10 s; HO 1.3 A for 4 s or CO 2. Although stunning treatment did not influence ultimate pH, muscle lightness, tenderness or cooking loss, drip loss and PSE incidence in LTL muscles from CO 2 stunned pigs were lower compared with ES pigs. Overall, ecchymosis and bone fractures were more prevalent in ES pigs compared with CO 2 stunned pigs. This research identified that stunning pigs with CO 2 compared with manual ES lowered the incidence of bone fractures, ecchymosis, PSE and drip loss of pork.

The significance of cooling rate on water dynamics in porcine muscle from heterozygote carriers and non-carriers of the halothane gene—a low-field NMR relaxation study

The post mortem changes in the chemical/physical state distribution of water were followed in pig muscle ( M. longissimus dorsi) from heterozygote ( n=12) and non-carriers ( n=12) of the halothane gene exposed to two different cooling profiles using continuous low-field NMR relaxation measurements. T 2 relaxation data were analyzed using distributed exponential fitting analysis. Independent of genotype post mortem changes were observed in the two water populations characterizing water within the myofibrillar space ( T 21) and the extra-myofibrillar space ( T 22), respectively, as a function of chilling regime. The effect was most pronounced in samples from heterozygote carriers of the halothane gene. The obtained results strongly suggest that improved water-holding capacity of muscles upon fast chilling can be ascribed to a reduced accumulation of extra-myofibrillar water in the meat post mortem, and it is hypothesized that differences in the accumulation of extra-myofibrillar water post mortem can be ascribed largely to the time at which disruption of cell membrane integrity takes place.

Feeding patterns, growth performance and carcass traits in group-housed growing-finishing pigs: the effect of terminal sire line, halothane genotype and age

AbstractThe effects of terminal sire line, halothane genotype and age on feeding patterns and growth performance were studied in 208 castrated growing-finishing pigs distributed in two batches. In batch 1 (no. = 130), pigs came from crosses of NN Landrace × Large White sows with a Pietrain Nn (Pi-Nn) or a Large White × Pietrain Nn terminal sire line (LwPi-Nn). In batch 2 (no. = 78), the same sows were used but crossed with three different terminal sire lines : a Pietrain nn (Pi-nn), and two Pietrain NN (Pi-NNa and Pi-NNb). Growth performance and feeding patterns of the progeny (Nn or NN for the halothane gene) were measured from 67 to 166 days of age. Pigs were housed in groups of 10 and 13 individuals in Batch 1 and 2, respectively, with a random mixed-breed and halothane genotype sample in each group (space allowance 1·3 m2 per pig and 1·1 m2 per pig, respectively). Feeding patterns were monitored with a computerized food intake recording system (IVOG®-station) and every 3 weeks pigs were weighed and backfat and loin-muscle depth were ultrasonically recorded (PIGLOG®). Carcass quality was assessed with the Fat-o-Meater grading probe. In batch 1, halothane genotype did not have a significant effect on any of the feeding patterns recorded, but Nn individuals had a significantly higher body weight (P &lt;0·05), loin-muscle depth (P &lt;0·05) and lower backfat thickness (P &lt;0·01) in the last measurement taken, 3/4 carcass loin depth (P &lt;0·05) and lower carcass last rib backfat (P &lt;0·05) than NN pigs. Terminal sire line had a significant effect on all feeding patterns recorded except for feeding rate, Pi-Nn sired pigs showing a significantly higher food intake per visit (P &lt;0·05) and feeder occupation time per visit (P &lt;0·05) and lower number of visits (P &lt;0·001) compared with LwPi-Nn sired pigs which, in turn, showed significantly higher food intake per day (P &lt;0·001) and feeder occupation time per day (P &lt;0·01). Terminal sire also affected growth performance and body composition, Pi-Nn sired pigs having a significantly lower body weight (P &lt;0·001) and backfat thickness (P &lt;0·001) but higher killing-out proportion and 3/4 loin depth (P &lt;0·01) than LwPi-Nn sired pigs. In batch 2, Pi-NNb sired pigs showed a significantly lower food intake per day compared with the progeny of the other two terminal sires lines at some of the age measurements taken (P &lt;0·05). The rest of the feeding patterns was not affected by terminal sire line. Body and carcass weights were also significantly lower (P &lt;0·01) for Pi-NNb sired pigs, but their killing-out proportion was higher than Pi-NNa sired pigs. With regard to these variables, Pi-nn sired pigs held an intermediate position between the two NN terminal sire lines. In both batches, age was associated with a significant increase in food intake per visit and per day and feeding rate (P &lt;0·001) and a decrease in feeder occupation time per visit and per day and frequency of visits to the feeder (P &lt;0·001). Overall, the present results suggest differences between terminal sire lines for feeding patterns and confirm their evolution with age from short and frequent meals to long and larger ones in growing-finishing pigs. Under our conditions, the effects of terminal sire line on feeding patterns and growth performance surpassed those of the halothane genotype.

The relationship between pig genetics, myosin heavy chain I, biochemical traits and quality of M. longissimus thoracis

The relationship between muscle biochemical traits, myosin heavy chain I and meat quality of longissimus thoracis was studied using gilts from five divergent porcine lines (A to E) (carcass weight: 83.7±8.7 kg). Intramuscular fat (IMF) and haem pigments content as well as myosin heavy chain 1 (MyHC I) percentage and the activity of lactate dehydrogenase (LDH) and isocitrate dehydrogenase (ICDH) were determined. Only group E, a well conformed line of pigs, included the halothane positive genotype. The presence of the Hal gene in this line resulted in meat of poorer quality in terms of meat of higher exudate compared to line D, also a well conformed line of predominantly Pietrain origin but being halothane gene free. Line C presented the highest IMF content (2.02%) as well as high oxidative characteristics (MyHC I, 10.0%; LDH/ICDH, 1.92 μmol nmol −1; ICDH activity, 1.78 nmol min −1 g −1) and the lowest drip losses (5.3%). According to a principal component analysis including MyHC I, biochemical traits and meat quality parameters, line C was characterized by a high IMF content and oxidative traits, and line B by a high glycolytic metabolism. Line E was distinguished by high drip losses and by low pH 45 and pH u. In conclusion, several observed differences in muscle metabolism between lines free of the halothane gene (A, B, C and D) must be caused by other “genetic background” factors.

Effect of the Halothane Gene on Pre-Slaughter Mortality in Two Spanish Commercial Pig Abattoirs

AbstractA total of 107 ear samples from all the pigs that died during transport or lairage at two commercial abattoirs were collected during two months (February and July), in order to determine their halothane genotype (NN, Nn or nn). The frequencies of the three halothane genotypes among dead pigs were significantly different (P &lt; 0.001), being 4.7%, 24.3% and 71.0% for NN, Nn and nn individuals, respectively. The frequencies of pre-slaughter deaths within each genotype were estimated to be 0.02%, 0.09% and 2.29% for NN, Nn and nn genotypes, respectively. According to these results, the removal of both nn and Nn genotypes would give rise to an eleven-fold reduction in the pre-slaughter mortality rate (from 0.22% to 0.02%). It is therefore suggested that, from an animal welfare point of view, the elimination of the halothane gene in existing breeding schemes would have a major beneficial impact.

Sensory and functional meat quality characteristics of pork derived from three halothane genotypes

The effect of the halothane gene in pigs on the meat and sensory qualities thereof were determined. Meat derived from 60 Landrace×Large White pigs of three halothane genotypes was used. The sensory qualities, cooking loss, colour, shear value and proximate analysis of the cooked pork loin roasts were determined. The three genotypes did not differ significantly ( P>0.05) with regard to the colour of the cooked meat, percentage cooking loss and percentage moisture. There were significant differences ( P<0.05) between the genotypes in the percentage protein, ash and fat. Meat from the three genotypes also differed significantly ( P<0.05) in juiciness, an analytical sensory panel scored the juiciness of meat from the NN-genotype the highest with a value of 71.3 when using a structured line scale. Meat from the nn-genotype had the lowest score for juiciness (62.8). Meat from the three genotypes did not differ significantly ( P>0.05) with regard to tenderness, pork flavour and no mealiness. Correlation values showed a positive correlation ( r=0.46, P<0.05) between juiciness and tenderness. These results indicate that the inclusion of the halothane gene in pig production programmes results in meat with an inferior quality and it can be recommended to exclude the halothane positive genotype from any pig production system where fresh pork quality is considered a primary goal.

The significance of pre-slaughter stress and diet on colour and colour stability of pork

The influence of pre-slaughter stress and a diet known to affect post mortem muscle metabolism or a standard diet (control pigs) on colour and colour stability of m. longissimus dorsi, m. biceps femoris and m. semimembranosus from 112 female pigs, free of the Halothane gene, was investigated. Pre-slaughter stress increased the early post mortem temperature in the three muscles, as well as the pH decline in control pigs, but not in pigs fed the experimental diet. Colour was measured on sliced samples after 0, 2 and 5 days retail display (1, 3 and 6 days post mortem, respectively) from the three muscles aged 1 day before cutting as well as on sliced m. longissimus dorsi samples aged 8 days before cutting (8, 10 and 13 days post mortem, respectively). Early post mortem pH was not a main determinant of the colour and colour stability, while the degree of pre-slaughter stress and especially its influence on temperature early post mortem was crucial in relation to colour development and colour stability. The discoloration rate was enhanced in m. longissimus dorsi aged for 8 days prior to retail display compared with samples aged for 1 day. However, the extent of the discoloration after 5 days of retail display was not inferior in muscle samples aged for 8 days due to a higher degree of blooming. Finally, present data indicate that 3–4 days ageing of pork prior to retail display results in the optimal colour stability.