Halothane Genotype Research Articles

Effect of gender and halothane genotype on cognitive bias and its relationship with fear in pigs

Cognitive bias (CB) has been recently proposed as a tool to study emotions by assessing the cognitive function through behaviour observation. It is based on the premise that subjects in a negative affective state perform more negative judgements about ambiguous stimuli than subjects in positive affective state. This study aimed at investigating if halothane genotype (homozygous Hal-free, NN vs. heterozygous Hal carrier, Nn) and gender (gilts, G vs. entire males, EM) affect the CB in pigs. Moreover, the results of the CB test (CBT) were compared with the results of a novel object test (NOT) in order to assess the influence of fear in the decision taken by pigs during the CBT. The results of both tests were contrasted with the concentration of brain neurotransmitters in four different brain areas in order to analyse the involvement of the dopaminergic and serotonergic pathways on the pigs’ affective state and fear. A total of 48 pigs, in terms of 12Hal-free gilts (NNG), 12Hal carrier gilts (NnG), and 12Hal-free entire males (NNEM) and 12Hal carrier entire males (NnEM) were put on the CBT at the age of 20 weeks and on the NOT four days later. After two days, pigs were slaughtered and four brain structures (amygdala, prefrontal cortex, hippocampus and hypothalamus) were dissected for the analysis of brain neurotransmitters. The CBT and NOT results did not show any effect of the genotype and gender or their interaction on pigs’ emotional response (p>0.10). However, the CBT correlated positively with the NOT (r=0.49; p=0.0005), with pigs classified with a negative CB tending to be more fearful in front of the novel object than those with a positive CB (p=0.05). Moreover, the pigs that took longer to get in contact with the novel object in the NOT also had lower (p=0.013) concentration of dopamine in the prefrontal cortex and increased DOPAC/dopamine ratio in the hypothalamus (p=0.003). These results suggest that fear level plays an important role in the decision taken by the pig dealing with ambiguous stimuli.

Modelagem hierárquica Bayesiana na avaliação de curvas de crescimento de suínos genotipados para o gene halotano

Para avaliar a influência do gene halotano sobre a curva de crescimento de suínos, bem como sua interação com o sexo do animal, foi proposta uma modelagem hierárquica Bayesiana. Nesta abordagem, os parâmetros dos modelos não-lineares de crescimento (Logístico, Gompertz e von Bertalanffy) foram estimados conjuntamente com os efeitos de sexo e genótipos do gene halotano. Foram utilizados 344 animais F2(Comercial x Piau) pesados ao nascer, aos 21, 42, 63, 77, 105 e 150 dias. O modelo Logístico foi aquele que apresentou melhor qualidade de ajuste por apresentar menor DIC (Deviance Information Criterion) que os demais. As amostras das distribuições marginais a posteriori para as diferenças entre as estimativas dos parâmetros do modelo Logístico indicaram que o peso dos machos à idade adulta com genótipo heterozigoto (HalNn) foi superior ao dos homozigotos (HalNN). A título de comparação, também foi considerada a abordagem frequentista tradicional, baseada em dois passos distintos, a qual, por apresentar um menor poder de discernimento estatístico, não mostrou diferenças significativas

Effect of the halothane genotype on intramuscular fat deposition in swine

Intramuscular fat (IMF) content has been identified as an important factor in determining the quality of pork. Previous studies have suggested that IMF deposition may be associated with the presence of the halothane (HAL) gene. This study aimed to evaluate the effect of the HAL gene on IMF deposition in crossbred pigs of commercial lines, which were killed at a slaughterhouse under official inspection. The genotype of the HAL gene was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. IMF was analyzed from longissimus dorsi samples. Among all animals analyzed, 42.36% were of the HalNN genotype and 57.64% were of the HalNn genotype. The average IMF content of all samples was 2.14%. Variation in IMF between genotypes was evaluated by analysis of variance. No significant difference in IMF deposition, which could be based on the presence of the halothane allele, was observed, at least in heterozygotes.

Reproductive and productive performances of the stress-negative Piétrain pigs in the tropics: the case of Vietnam

The objective of the present study is to investigate the reproduction, production and semen traits of the stress-negative Piétrain line of pigs in the north of Vietnam, as well as to identify various factors (halothane genotype, generation-origin, parity, sex and month of the year) acting on these traits. The experiment was carried out on a purebred nucleus on Dong Hiep farm, Haiphong province in Vietnam. The reproduction performances and the sperm quality measures were based on 12 sows and 5 boars imported from Belgium as well as on 29 sows and 14 boars born in Vietnam, while the production performances were recorded only from 251 animals born in Vietnam. No significant differences were observed between halothane genotypes of sows for reproduction traits (P > 0.0578). At the age of 7.5 months, bodyweight, backfat thickness and longissimus depth (7.5) of homozygous-dominant pigs were higher (P < 0.05) than in heterozygotes. Homozygous-dominant boars had higher total number of spermatozoa than heterozygote boars (P < 0.05); similarly, Vietnam boars also presented higher total number of spermatozoa values than Belgium boars (P < 0.001). Vietnam sows had longer duration of pregnancy, more piglets born alive and heavier litter weight of weaning than Belgium sows (P < 0.01). Bodyweight at birth, at weaning, at 2, 5.5 and 7.5 months of age increased from the first to third parity (P < 0.05). Gilts had more lean meat than intact boars (P < 0.01). Compared with observations made in temperate countries, the reproduction and production performances, sperm concentration and total number of spermatozoa of stress-negative Piétrain pigs were reduced, whereas lean meat percentage was not affected. This might be due to the different climate, although improving values for animals born in Vietnam might indicate adaptation of the animals and/or of the technicians with that breed. The results support the interest of the use of this new Piétrain line in tropical countries with ecological and climatic conditions similar to Vietnam.

Effects of trailer design on animal welfare parameters and carcass and meat quality of three Pietrain crosses being transported over a long distance1

This study aimed at evaluating the effects of trailer design on stress responses and meat quality traits of 3 different pig crosses: 50% Pietrain breeding with halothane (HAL)(Nn) (50Nn); 50% Pietrain breeding with HAL(NN) (50NN); and 25% Pietrain breeding with HAL(NN) genotype (25NN). Over a 6-wk period, pigs (120 pigs/crossbreed) were transported for 7 h in either a pot-belly (PB) or flat-deck (FD) trailer (10 pigs/crossbreed(-1)·trailer(-1)·wk(-1)). Temperature (T) and relative humidity (RH) were monitored in each trailer. Behaviors during loading and unloading, time to load and unload, and latency to rest in lairage were recorded, whereas a sub-population of pigs (4 pigs/crossbreed(-1)·trailer(-1)·wk(-1)) was equipped with gastro-intestinal tract (GIT) temperature monitors. Blood samples were collected at exsanguination for measurement of cortisol, creatine kinase (CK), lactate, haptoglobin, and Pig-MAP concentrations. Meat quality data were collected at 24 h postmortem from the LM and semimembranosus (SM) and adductor (AD) muscles of all 360 pigs. Greater T were recorded in the PB trailer during transportation (P = 0.006) and unloading (P < 0.001). Delta GIT temperature was greater (P = 0.01) in pigs unloaded from the PB. At loading, pigs tended to move backwards more (P = 0.06) when loaded on the FD than the PB trailer. At unloading, an interaction was found between trailer type and crossbreed type, with a greater (P < 0.01) frequency of overlaps in 50NN and 25NN pigs and slips/falls in 50Nn and 50NN pigs from the FD than the PB trailer. Cortisol concentrations at slaughter were greater (P = 0.02) in pigs transported in the PB than FD trailer. Greater lactate concentrations were found in 50Nn and 50NN pigs (P = 0.003) and greater CK concentrations (P < 0.001) in 50Nn pigs. As expected, 50Nn pigs produced leaner (P < 0.001) carcasses, with greater (P = 0.01) dressing percentages, as well as lower (P < 0.001) ultimate pH values and greater (P < 0.001) drip loss percentages in the LM and greater (P = 0.002) drip losses and a paler color (greater L* values, P = 0.02) in the SM than 50NN pigs. When used for long distance transportation under controlled conditions, the PB trailer produced no detrimental effects on animal welfare or pork quality. Pigs with 50% Pietrain crossbreeding appear to be more responsive to transport stress, having the potential to produce acceptable carcass and pork quality, provided pigs are free of the HAL gene.

Mapeamento de QTL nos cromossomos 1, 2, 3, 12, 14, 15 e X em suínos: características de carcaça e qualidade de carne

A realização do presente estudo teve como objetivo mapear Quantitative Trait Loci (QTL) de carcaça e qualidade de carne em uma população F2 de suínos desenvolvida pelo cruzamento de dois reprodutores da raça brasileira Piau com 18 fêmeas comerciais (Landrace x Large White x Pietrain). O mapa de ligação para essa população foi construído após a genotipagem de 684 animais para 35 marcadores microssatélites. Os dados foram analisados pelo mapeamento por intervalo usando-se sexo, lote e genótipo halotano como efeitos fixos e peso de carcaça ao abate, peso da carcaça direita e idade ao abate como covariáveis. Um total de 18 QTLs foi encontrado; os QTLs para maior espessura de toucinho na região da copa, na linha dorsolombar, e a perda por cozimento foram significativos em nível de 5% genômico. A característica espessura de toucinho foi essencialmente associada aos alelos da raça Piau, conhecido como porco tipo banha. As informações dos QTLs significativos encontrados servem para futuros estudos de mapeamento fino para identificação de genes a serem usados em conjunto com os métodos tradicionais de seleção, para melhorar a eficiência dos programas de melhoramento, assim como prover informação acerca da fisiologia envolvida no desenvolvimento das características quantitativas dos suínos.

Genetic parameters and halothane genotype effect for residual feed intake in Piétrain growing pigs

Data were collected in the frame of the French pig breeding scheme for the Piétrain breed in which the halothane sensitivity allele (n) is segregating. This data set was used to estimate: (1) genetic parameters for residual feed intake (RFI) and growth, body composition and meat quality traits and (2) effect of the three halothane genotypes on these traits. Individual feed intake of animals raised from 35 to 107kg body weight in collective pens (12 animals maximum) was recorded using single-place electronic feeders. A total of 2312 animals were tested between 2002 and 2009 in three French central test stations: 176 were homozygous non-sensitive (NN), 470 were heterozygous (Nn) and 1666 were homozygous sensitive (nn) for the halothane locus. Variance components were estimated using the REML methodology applied to a multitrait animal model, including a random litter effect and, for meat quality traits, a random slaughter day effect. RFI showed a moderate heritability (0.40±0.06), similar to the estimate for feed conversion ratio (FCR, 0.47±0.07), with a genetic correlation of 0.85±0.04 between these traits. Pairwise contrasts between halothane genotypes showed that the halothane genotype did not affect RFI, contrary to FCR (P<0.01 for all pairwise contrasts). We conclude that, in the Piétrain breed, improving feed efficiency by selecting for lower RFI would improve FCR and reduce daily feed intake with limited impacts on growth rate and carcass traits. Moreover, it is not expected to modify the frequencies of the halothane alleles in the population, contrary to selection for reduced FCR.

Influence of the halothane gene (HAL) on pork quality in two commercial crossbreeds

We evaluated the effect of the halothane (HAL) gene on the quality of pork in domestic pigs. Half-carcasses from two different commercial pig (Sus domestica) crossbreeds were analyzed, 46 of which were homozygous dominant (HAL(NN)) and 69 of which were heterozygous (HAL(Nn)) for the halothane gene. The measures included backfat thickness, lean meat percentage, carcass weight, pH 24 h after slaughtering, color, and drip loss; DNA was extracted from the haunch muscle. Swine with the HAL(Nn) genotype had less backfat thickness and higher lean meat percentages than swine with the HAL(NN) genotype. Yet, swine with the HAL(Nn) genotype had lower quality meat than those with the HAL(NN) swine. The pH at 24 h was lower in HAL(Nn) swine. The meat color was paler in HAL(Nn) animals, the drip loss was greater in those animals bearing the n allele, and the amount of intramuscular fat was not related to the halothane genotype. We conclude that bearers of the recessive allele of the halothane gene produce more meat, but with quality parameters that are inferior to those sought by consumers and industry.

Meta-analysis of the effect of the halothane gene on 6 variables of pig meat quality and on carcass leanness1

Technological meat quality is a significant economic factor in pork production, and numerous publications have shown that it is strongly influenced both by genetic status and by rearing and slaughter conditions. The quality of meat is often described by meat pH at different times postmortem, as well as by color and drip loss, whereas carcass quality is often characterized by lean percentage. A meta-analysis of findings relating to 3,530 pigs reported in 23 publications was carried out to assess the effects of the halothane gene, sex, breed, and slaughter weight of animals on 7 selected variables: pH at 45 min postmortem, ultimate pH, reflectance (L*-value), redness (a*-value), yellowness (b*-value), drip loss, and lean percentage. Two statistical methods were used in the meta-analysis: the method of effect size and the better known random effects model. The method of effect size was associated with Markov chain Monte Carlo techniques for implementing Bayesian hierarchical models to avoid the problems of limited data and publication bias. The results of our meta-analysis showed that the halothane genotype had a significant effect on all analyzed pork quality variables. Between-study variance was evaluated with the Cochran (1954) Q-test of heterogeneity. Meta-regression was used to explain this variance, with covariates such as breed, sex, slaughter weight, and fasting duration being integrated into different regression models. The halothane gene effect was associated with the breed effect only for the following variables: L*-value, b*-value, and drip loss. Slaughter weight contributed significantly only to the explanation of differences in ultimate pH between homozygous genotypes. In response to inconsistencies reported in the literature regarding the difference between the genotypes NN and Nn, results of the meta-analysis showed that the difference between these 2 genotypes was significant for all the analyzed variables except the a*-value.

Detecting QTL for feed intake traits and other performance traits in growing pigs in a Piétrain–Large White backcross

Knowing the large difference in daily feed intake (DFI) between Large White (LW) and Piétrain (PI) growing pigs, a backcross (BC) population has been set up to map QTL that could be used in marker assisted selection strategies. LW × PI boars were mated with sows from two LW lines to produce 16 sire families. A total of 717 BC progeny were fed ad libitum from 30 to 108 kg BW using single-place electronic feeders. A genome scan was conducted using genotypes for the halothane gene and 118 microsatellite markers spread on the 18 porcine autosomes. Interval mapping analyses were carried out, assuming different QTL alleles between sire families to account for within breed variability using the QTLMap software. The effects of the halothane genotype and of the dam line on the QTL effect estimates were tested. One QTL for DFI (P < 0.05 at the chromosome-wide (CW) level) and one QTL for feed conversion ratio (P < 0.01 at the CW level) were mapped to chromosomes SSC6 – probably due to the halothane alleles – and SSC7, respectively. Three putative QTL for feed intake traits were detected (P < 0.06 at the CW level) on SSC2, SSC7 and SSC9. QTL on feeding traits had effects in the range of 0.20 phenotypic s.d. The relatively low number of QTL detected for these traits suggests a large QTL allele variability within breeds and/or low effects of individual loci. Significant QTL were detected for traits related to carcass composition on chromosomes SSC6, SSC15 and SSC17, and to meat quality on chromosome SSC6 (P < 0.01 at the genome-wide level). QTL effects for body composition on SSC13 and SSC17 differed according to the LW dam line, which confirmed that QTL alleles were segregating in the LW breed. An epistatic effect involving the halothane locus and a QTL for loin weight on SSC7 was identified, the estimated substitution effects for the QTL differing by 200 g between Nn and NN individuals. The interactions between QTL alleles and genetic background or particular genes suggest further work to validate QTL segregations in the populations where marker assisted selection for the QTL would be applied.

Effect of pre-slaughter transport plant on blood constituents and meat quality in halothane genotype of NN Large White × Landrace pigs

A 3 × 3 factorial experiment has been conducted to study the effects of different transport time (Short: 40 min vs. Medium: 3 h vs. Long: 5 h) and stocking densities (Low: 5 pigs per pen or 230 kg/m 2, Medium: 6 pigs per pen or 275 kg/m 2 and High: 7 pigs per pen or 325 kg/m 2) on some blood constituents and meat quality of four hundred and thirty two pigs including seventy two pigs that had been DNA tested (genotype: NN). The results are as follows: 1) Lactate dehydrogenase enzymatic activity increased as transport time increased, but it reached significance only for the high density group ( P < 0.05). Lactate concentration was significantly lower in the group subjected to 3 h transport and low stocking density ( P < 0.05). The concentration of cortisol was higher after 5 h transport than those transported for shorter time (40 min or 3 h; P < 0.05) and also significantly increased ( P < 0.05) in the highest stocking density. The stocking density treatment had a difference tendency that ACTH concentration gradually increased as density enhanced. 2) Drip loss, pH u and Opto-star u were significantly affected by transport time in the longissimus thoracis muscle. Opto-star u was the only meat quality that was affected by transport time in the semimembranosus muscle, while the values of pH 1, pH u, Opto-star 1 and Opto-star u were lower ( P < 0.05) in the low density group than medium or high density group. 3) The pigs from the 3 h transport group had significantly lower RBC, HGB and HCT ( P < 0.05) compared with the short or long time transport groups. At the same time, pigs under the long time transport showed lower count of LYM than pig under 1 and 3 h transport conditions. Hence, from these data we conclude that the most adequate pre-slaughter transport time was 3 h for medium stocking density (less than 275 kg/m 2) and at a warm environmental temperature in the Chinese commercial transport conditions.

Effects of breed, sex and halothane genotype on fatty acid composition of triacylglycerols and phospholipids in pork longissimus muscle

The objective of this study was to estimate the effects of breed, sex, and halothane (HAL-1843) genotype on fatty acid composition of triacylglycerols (TAG) and phospholipids (PL) extracted from porcine longissimus muscle (LM). Purebred Yorkshire (n = 131), Duroc (n = 136), Hampshire (n = 49), Spotted (n = 35), Chester White (n = 74), Poland China (n = 51), Berkshire (n = 169) and Landrace (n = 82) pigs (n = 727; 427 barrows and 300 gilts) from the 1994 and 2001 National Barrow Show Sire Progeny Tests were used. For statistical analyses, a mixed model was used that included fixed effects of breed, sex, HAL-1843(TM) genotype, year, slaughter date within each year, interaction of breed x sex and random effects of sire and dam within breed. Breeds and sex were significantly associated with the percentages of the majority fatty acids in TAG. Duroc pigs had greater total saturated fatty acids (SFA) and lower total monounsaturated fatty acids (MUFA) (p < 0.05) contents than did pigs of all other breeds except Berkshire (p > 0.05). The concentration of total polyunsaturated fatty acids (PUFA) was the greatest in Hampshire pigs (p < 0.05). The content of total SFA was greater (p < 0.01), whereas the concentrations of total MUFA and PUFA were lower (p < 0.01) in barrows than those in gilts. The contents of major SFA in PL did not differ significantly among pigs from different breeds and sex groups. However, breed and sex significantly affected the concentrations of major MUFA and PUFA in PL and strong negative correlation between the total contents of MUFA and PUFA in PL was observed in the current study. Chester White pigs had greater total MUFA and lower total PUFA contents (p < 0.05) in PL than did pigs of all other breeds except Spotted (p > 0.05). In contrast to breed and sex effects, the concentrations of fatty acids in PL were more affected by HAL-1843 genotype than those in TAG. The content of C16:0, a major SFA in PL, differed significantly in pigs with different HAL-1843 genotypes. In conclusion, these results suggest that breed and sex are important sources of the variations for fatty acid composition of TAG and PL in LM.

Effect of magnesium sulphate and l-tryptophan and genotype on the feed intake, behaviour and meat quality of pigs

Sixty-nine entire male pigs with different halothane genotype (homozygous halothane positive — nn-, n = 36; and homozygous halothane negative — NN-, n = 33) were fed with a supplementation of magnesium sulphate (Mg) and/or l-tryptophan (Trp) in the diet for 5 days before slaughter. Animals were housed individually and were submitted to stressful ante mortem conditions (mixed in the lorry according to treatments and transported 1 h on rough roads). Individual feed intake was recorded during the 5-d treatment. At the abattoir, pig behaviour was assessed in the raceway to the stunning system and during the stunning period by exposure to CO 2. Muscle pH, colour, water holding capacity, texture and cathepsin activities were determined to assess meat quality. The number of pigs with an individual feed intake lower than 2 kg/day was significantly different among diets ( P < 0.05; Control: 8.7%; Mg&Trp: 43.5%; Trp: 17.4%) and they were considered to have inadequate supplement intake. During the ante mortem period, 15.2% of pigs included in the experiment died, and this percentage decreased to 8.7% in those pigs with a feed intake > 2 kg/day, all of them from the stress-sensitive pigs (nn). In general, no differences were observed in the behaviour of pigs along the corridor leading to the stunning system and inside the CO 2 stunning system. During the stunning procedure, Trp diet showed shorter periods of muscular excitation than control and Mg&Trp diets. The combination of a stressful ante mortem treatment and Mg&Trp supplementation led to carcasses with high incidence of severe skin lesions. Different meat quality results were found when considering all pigs or considering only those with adequate supplement intake. In this later case, Trp increased pH 45 (6.15) vs Control diet (5.96) in the Longissimus thoracis (LT) muscle ( P < 0.05) and pH at 24 h (Trp: 5.59 vs C: 5.47) led to a higher incidence of dark, firm and exudative (DFD) traits in SM muscle ( P < 0.05). Genotype affected negatively all the meat quality traits. Seventy-five percent of LT and 60.0% of the SM muscles from nn pigs were classified as pale, soft and exudative (PSE), while none of the NN pigs showed these traits ( P < 0.0001). No significant differences were found between genotypes on the incidence of DFD meat. Due to the negative effects observed in the Mg&Trp group in feed intake and carcass quality, the utilization of a mixture of magnesium sulphate and tryptophan is not recommended.

Carcass quality of crossbred pigs with Pietrain as a terminal sire

The aim of this paper was to investigate the effect of the crossbreed and halothane genotype on carcass quality traits of fatteners from commercial pig farm. Study was carried out on 68 crossbred pigs divided into two groups according to sow genotype: Large Whitex Swedish Landrace (LWxSL) and Large White x German Landrace x (LWxGL). Both sow genotypes were mated with Pietrain (P) as a terminal sire. Influence of crossbreeding and halothane genotype on cold carcass weight, carcass length, dressing percentage and lean percentage, slaughter line measurements as well as fat and M. Longissimus dorsi areas were not significant (P>0.05). The value of pH45 measured in M. Longissimus dorsi was higher in Px(LWxGL) crossbreeds and dominant homozygote genotype (P<0.05). Measurements of pH24 were not significantly different (P>0.05) between crossbreeds and halothane genotypes. Except for pH45 value, most of other measured carcass quality traits were not affected by crossbreeding combination and halothane genotype (P>0.05).

INFLUENCE OF BREED, SEX AND GROWTH HORMONE AND HALOTHANE GENOTYPES ON CARCASS COMPOSITION AND MEAT QUALITY TRAITS IN PIGS

ABSTRACT The objective of this study was to verify the influence of the growth hormone (GH) and halothane (Hal) genotypes, breed and sex on carcass and meat quality. Ninety‐six pigs (Piétrain, Large White and Landrace) were dissected. For each breed, 16 were noncastrated males and 16 were females. The Piétrain animals presented the greatest lean meat percentage, the heaviest ham and shoulder and the lightest belly weight and fat thickness. Landrace presented the heaviest belly. Females presented the greatest drip loss; L*, b* and fat thickness; the heaviest ham and loin; and the lightest shoulder and tenderloin. Hal–NN and Nn presented greater loin weight than nn animals. Nn animals presented smaller belly weight than homozygotes. The nn animals presented greater drip loss than NN and Nn, and greater lean meat than NN. Interestingly, GH–D2D2 animals also showed higher drip loss than those with D1D1 genotype. This investigation presents relevant associations between important economic traits and specific GH and Hal genotypes.PRACTICAL APPLICATIONSThe identification of new molecular markers related to pig production has been increasing in importance, especially when these markers are related to carcass and meat quality traits, which are difficult to predict. When a marker is intensively used in a selection program, it reaches fixation, so it is important to identify new markers to replace it. This work shows, for the first time, the association of a GH polymorphism with an important meat quality trait and reinforces the possibility of its use in programs of marker‐assisted selection.

Aversion to carbon dioxide stunning in pigs: effect of carbon dioxide concentration and halothane genotype

AbstractAversion to the dip-lift stunning system and to the inhalation of 70 and 90% carbon dioxide was assessed in 18 halothane-free (NN) and 14 heterozygous halothane (Nn) slaughter weight pigs using aversion learning techniques and behavioural studies in an experimental slaughterhouse. Pigs were subjected to the treatments individually. When the dip lift system contained atmospheric air, the proportion of pigs that entered the crate voluntarily increased on subsequent days, indicating that pigs habituate to the stunning system. Based on the number of attempted retreats, for the first descent into the well with atmospheric air, Nn pigs were more reactive than NN pigs. On repeating the descent, Nn pigs showed greater habituation to the procedure. When the pit contained (either 70 or 90%) carbon dioxide, the time taken to enter the crate and the incidence of pigs that attempted to retreat increased on subsequent days, indicating aversion to the carbon dioxide concentrations. The aversion was higher when the stunning system contained 90 as opposed to 70% carbon dioxide due possibly to increased irritation of the nasal mucosal membranes and more severe hyperventilation. Conversely, a decrease in the concentration of carbon dioxide increased the time to loss of posture and, therefore, lengthened the perception of the aversive stimulus till the animal lost consciousness. These results suggest that stunning with carbon dioxide is not free from pain or distress. The degree of aversion depends on the carbon dioxide concentration. Therefore, if higher concentrations of carbon dioxide are recommended for rapid induction of anaesthesia, it needs to be assumed that this may be more aversive to pigs.

Effect of supplementation with MgCO3 and l-Tryptophan on the welfare and on the carcass and meat quality of two halothane pig genotypes (NN and nn)

Sixty-one animals with different Halothane genes (homozygous halothane positive, n=34; and homozygous halothane negative, n=27) were fed with three diets (control group, with no supplement; magnesium (Mg) group with 1.28 g MgCO3/kg and tryptophan (Trp) group with 5 g l-Trp/kg) during the last 5 days before slaughter. Animals were submitted to minimal stress antemortem conditions. Pig behaviour was recorded at the experimental farm, raceway to the CO2 stunning system and during the stunning period. Corneal reflexes were recorded after stunning as well. There were no differences in feed intake among diets (P>0.05) during the 5 days of treatment. The halothane positive (nn) group had lower intake than the halothane negative (NN) group (P<0.01). The behaviour of the pigs in the raceway did not differ (P>0.05) among treatments or halothane genotype. A significant (P<0.001) interaction diet⁎halothane was found in the time to appear the first retreat attempt during the exposure to the CO2 system. In the nn group, the time of performing the first retreat attempt was later in the Mg (P<0.05) than the control group. Moreover, in the Mg group, the nn had a later (P<0.05) first retreat attempt than the NN. Thus, Mg supplementation could have a positive effect on welfare of nn pigs. The nn had a lower proportion of animals that showed corneal reflexes after stunning than NN, indicating a higher effectiveness of the stunning method in nn pigs. Neither Mg nor Trp affected carcass quality and meat quality parameters, although significant differences were found between genotypes.

Influence of lipid content on pork sensory quality within pH classification1

The objective of this project was to determine the contribution of lipid content to textural and sensory properties of fresh pork within defined pH classifications. Pigs (n = 1,535; from 248 sires and 836 dams) from the 1991, 1992, and 1994 National Barrow Show Sire Progeny Test were used in this study. The test included purebred Berkshire (107), Chester White (113), Duroc (249), Hampshire (220), Landrace (165), Poland China (101), Spotted (181), and Yorkshire (399) barrows (901) and gilts (634). Diets were uniform across breeds within test. The halothane (Hal 1843) genotype (1346 NN and 189 Nn) was determined. Pigs were slaughtered at 105 kg of BW, and samples of the LM were obtained from each carcass at the 10th rib. Star probe, sensory traits, and lipid content were determined on the LM from each pig. A pH classification of LM was assigned as follows: class A, > 5.95, n = 186; class B, > or = 5.80 to 5.95, n = 236; class C, > or = 5.65 to 5.80, n = 467; class D, > or = 5.50 to 5.65, n = 441; class E, < 5.50, n = 205. Data were analyzed using a mixed linear model including pH classification, test, sex, halothane genotype, breed, and breed x sex interaction as fixed effects, with sire and dam within breed included as random effects. Correlations were determined within pH class. Lipid content was a significant source of variation for models predicting star probe values in class C and D and for chewiness in class B, C, and D. Increasing lipid content tended to increase sensory tenderness in pH class D. Sensory tenderness was not affected by lipid content in pH class A, B, or E. Lipid content was not a significant source of variation for juiciness scores within any pH class. Intramuscular lipid is correlated with sensory texture traits primarily in classes C and D. Within class C and D, correlations indicate that increasing lipid content is associated with high sensory tenderness, low sensory chewiness, and low star probe values. It is concluded that lipid content is a small source of variation in texture and tenderness of pork loin with pH between 5.80 and 5.50, but not at a greater or lesser pH.

Effects of breed, sex, and halothane genotype on fatty acid composition of pork longissimus muscle1

The objective of this study was to estimate the effects of breed, sex, and halothane genotype on fatty acid composition and several fatty acid indices of lipid extracted from porcine LM. Purebred Yorkshire (n = 436), Duroc (n = 353), Hampshire (n = 218), Spotted (n = 187), Chester White (n = 173), Poland China (n = 124), Berkshire (n = 256), and Landrace (n = 187) pigs (n = 1,934; 1,128 barrows and 806 gilts) from 1991, 1992, 1994, and 2001 National Barrow Show Sire Progeny Tests were used. Pigs were classified as the HAL-1843 normal (NN) genotype (n = 1,718) or the HAL-1843 carrier (Nn) genotype (n = 216). For statistical analysis, a mixed model was used that included fixed effects of breed, sex, halothane genotype, test, slaughter date, interaction of breed x sex, and random effects of sire and dam within breed. Breed significantly affected the concentration of individual fatty acids, total lipid content, and the values of several fatty acid indices of LM. Duroc pigs had the greatest (P < 0.01) content of total SFA. Total MUFA concentration in Poland China pigs was greater (P < 0.05) than in all other breeds except the Spotted (P > 0.05). The concentrations of total PUFA were greater (P < 0.01) in Hampshire, Landrace, and Yorkshire pigs compared with those of other breeds. Significant sex differences for individual fatty acids were detected. Compared with gilts, barrows had greater (P < 0.01) concentrations of SFA and MUFA but lower (P < 0.01) total PUFA. Halothane genotype was a significant source of variation for the percentages of some fatty acids. Pigs with the carrier (Nn) genotype had lower concentrations of SFA (P < 0.05) and MUFA (P < 0.01) but a greater concentration of PUFA (P < 0.01) compared with NN pigs. There were significant negative correlations between total lipid content and individual PUFA and significant positive correlations between lipid concentration and most individual SFA and MUFA. In conclusion, the results suggest that breed and sex are important sources of variation for fatty acid composition of LM.

Hsp70 response in pigs is affected by their Halothane genotypes after heat stress

Heat shock protein ([Hsp70]) and ionized calcium ([Ca 2+]) concentrations were examined in pigs’ blood at different times after heat stress (HS). Pigs were from different halothane genotypes (HAL) (NN, n=7; Nn, n=5; nn, n=6). [Hsp70] increased significantly from 1–2 h after HS and [Ca 2+] decreased significantly from HS-end in NN and Nn. No significant differences in [Hsp70] and [Ca 2+] were detected among NN and Nn. [Hsp70] and [Ca 2+] in nn did not vary significantly from baseline values. [Hsp70] was significantly higher in NN and Nn than in nn. Briefly, HAL affected [Hsp70] after HS in pigs probably via a disordered [Ca 2+] regulation.