Muscle glycogen level and meat quality in pigs of different halothane genotypes

The halothane genotype of 22 Polish landrace pigs was determined using halothane test and blood typing. Eight homozygous normal (NN), eight hetero-zygotes (Nn) and six homozygous recessive (nn) were identified. The levels of glycogen and lactate were measured in biopsy samples taken from the longissimus lumborum using a shot biopsy technique. pH (pH(1)) and IMP/ATP ratio (R) were determined at 30 min after slaughter, while pH, meat colour and water holding capacity were determined on the day after slaughter. The halothane genotype did not affect intra vitam glycogen level. The nn pigs had a higher R value and lower pH(1) than both Nn and NN animals. Heterozygous animals were intermediate between both homo-zygotes for biopsy lactate level and meat colour. The lactate content of biopsy samples was significantly correlated with pH(1) (r = -0·68; P < 0·01), R (r = 0·68; P < 0·01), meat colour (r = 0·57; P < 0·01) and water holding capacity (r = 0·45; P · 0·05).     

Texture and rheological properties of meat from pigs of different halothane genotypes

The effects of halothane genotype (NN, Nn and nn) in pigs on meat texture, rheological properties, fibre diameter, area of intramuscular fat, pH, colour, drip loss, cooking loss and yield of cooked and of smoked loin were examined. Cooked and smoked meat of NN pigs exhibited lower hardness, gumminess, chewiness, elasticity moduli, greater cohesiveness and a longer relaxation time compared to meat from pigs with genotype Nn or nn. Meat from pigs of the nn genotype exhibited the greatest hardness and elasticity, the shortest relaxation time and the lowest viscosity and cohesiveness, while meat from genotype Nn was intermediate regarding these parameters. Significant correlations were found between parameters of texture, and rheological properties and pH, structure, drip and cooking loss. © 1998 SCI.     

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.     

Influence of porcine stress on blood composition and early post-mortem meat quality in pigs of different halothane genotypes

The purpose of this study was to investigate porcine stress, blood serum values and early post-mortem (pm) meat quality in pigs of unknown and known halothane genotype. Collection, transportation and slaughtering of the pigs were studied from the farm up to the carcass chilling (45 min pm). Reactors (nn) had the highest creative kinase (CK) activity. CK activity increased most prominently during transport in reactors, and at the abattoir in non-reactors (Nn or NN). The content of serum glucose was highest in non-reactors and lowest in non-carriers (NN, P<0·01). Serum glycerol level was highest in reactors and lowest in carriers (Nn, P < 0·05). Differences in serum lactate and pH values were not significant. Carriers had the highest and non-reactors the lowest carcass temperature, 0 min pm (P = 0·001). Temperature of non-reactors increased most rapidly (9·4%) and that of carriers increased most slowly (0·9%) during scalding. Reactors had the most rapid (3·1%) and carriers the slowest (0·3%) fall in carcass temperature between scalding and chilling. No significant differences were found between halothane genotypes in the rate of glycogen breakdown and lactate formation, 45 min pm. PSE (pH(1) ≤ 5·8) frequencies of reactors, non-reactors, non-carriers and carriers were 100·0, 14·3, 13·0 and 12·5, respectively.     

Combined effects of pre-slaughter treatments and lairage time on carcass and meat quality in pigs of different halothane genotype

The effect of two different lairage times on meat quality was investigated in pigs with different halothane genotype previously submitted to controlled pre-slaughter treatments. One hundred and ninety nine Italian heavy pigs were loaded by ramp or lift and transported unmixed for 1 h to the abattoir at a stocking density of either <0.4 or >0.6 m(2) per 100 kg pigs. After unloading, an equal number of animals within each previous treatment was held in lairage for 2 h or overnight (22 h) before slaughter. Carcass and meat quality and incidence of skin damage were evaluated. Longer lairage did not negatively affect carcass traits and reduced the incidence of PSE meat without increased DFD occurrence. It also seriously increased the amount of skin damage due to fighting, resulting in long fasting. Pre-slaughter treatments and halothane genotype showed a negligible effect on the response to the resting time.     

Comparison of Duroc and British landrace pigs for meat a and eating quality

Duroc and halothane negative British Landrace boars and gilts were performance tested from 30 to 80kg on ad-libitum or restricted feeding regimes, with like-sexed non-littermate groups of pigs penned together. Meat and eating quality was determined using objective laboratory measurements and by taste panel and consumer panel assessment on 160 pigs with 20 full-sib families for each breed, and two boars and two gilts per family. Duroc M. longissimus(?) was darker in colour, had a more intense, redder colour and contained more fat and less moisture than Landrace muscle. Duroc subcutaneous fat was less firm, had a higher water content and concentrations of linoleic acid and lower concentrations of stearic acid than Landrace fat. The taste and consumer panels scored Duroc meat as being more juicy, but less tender, having poorer flavour and being less acceptable than Landrace meat. The higher juiciness scores of Duroc meat were probably attributable to the higher intramuscular fat content compared to Landrace meat. Duroc boars had lower values for flavour liking and acceptability compared to other breed-sex combinations which may be due to the particular fatty acid composition of the subcutaneous fat in Duroc boars.     

Muscle fibre characteristics and metabolic response at slaughter in pigs of different halothane genotypes and their relation to meat quality

Muscle samples for histochemical and biochemical analyses were taken immediately at slaughter from M. longissimus dorsi of pigs with different halothane genotypes (NN and nn). Fibre type composition was similar between groups but the nn-genotype had larger mean fibre areas and lower capillary density than the NN-genotype. At exsanguination the nn-genotype had lower muscle pH (pH(e)), higher lactate and ammonia and lower glycogen and phosphagen (ATP and CP) concentrations and twice as many glycogen-depleted type IIA and IIB fibres as compared with the NN-genotype. Muscle pH(e) was correlated positively to capillary density, glycogen and phosphagen concentrations and negatively to mean fibre area, ammonia and lactate concentrations. Ammonia concentrations were correlated negatively to ATP concentrations and positively to the percentage of glycogen-depleted IIB fibres. The highest reflectance and drip loss values were seen in the nn-genotype. The reflectance values were correlated positively to the percentage of glycogen-depleted type IIB fibres in muscle and the values for drip loss were correlated negatively to pH(e). These data show that fibre size and capillary density in muscle seem to be important factors that influence the metabolic response at slaughter and thus meat quality.     

Effects of electrical stimulation on early postmortem muscle pH and temperature declines in pigs from different genetic lines and halothane genotypes

The objective of this study was to determine if electrical stimulation (ES) early postmortem is an effective method to generate PSE-like meat. One hundred and thirty-eight gilts (85-125 kg) from heavy muscled (HM), normal muscled (NM), and light muscled (LM) porcine genetic lines were subjected to one of two treatments: ES (26 pulses of 500 V, 60 Hz) at 3 min postmortem or non-stimulated (NS). Pigs from HM line were further characterized as halothane (HAL) carriers (Nn) or non-carriers (NN). ES carcasses had lower (P<0.0001) pH values and higher (P<0.0001) temperature than NS carcasses during the first 56 min postmortem. ES carcasses had lower (P<0.0001) a*-values, and color and firmness scores, as well as higher (P<0.0001) drip loss and L*-values. No significant interactions were found between treatment and genetic line or HAL gene status with regard to pH, temperature, or quality characteristics. Temperature and pH declines within the first hour postmortem were not affected by genetic line, but slight (P<0.01) quality differences were observed. Nn and NN did not differ in pH or temperature within the first hour postmortem, but Nn carcasses had lower (P<0.01) color and firmness scores, and higher (P<0.05) drip loss. These results show that ES early postmortem is an effective method for simulating PSE development in pigs of different muscling and HAL gene status, and suggest that pH and temperature decline alone cannot explain all aspects of pork quality.     

Influence of loading method and stocking density during transport on meat and dry-cured ham quality in pigs with different halothane genotypes

The effect of loading method and stocking density in transit on meat and dry-cured ham quality was investigated in pigs with different halothane genotypes. A total of 507 Italian heavy pigs, supplied by two farms, were loaded by ramp or lift and transported unmixed for 35–55 min to the abattoir at a stocking density of either <0.4 or >0.6m² per 100 kg pigs. After overnight lairage in separate pens with free access to water, the pigs were slaughtered. Halothane genotype was assessed post mortem. Four hundred and thirty-nine pigs had a homozygous dominant (NN) genotype and 68 pigs were heterozygous (Nn). Carcass skin damage, meat quality traits and ham curing parameters were evaluated. Loading method and stocking density showed a negligible effect on meat and dry-cured ham quality while the predominant factor affecting these was the halothane genotype. Nn pigs produced meat with a faster rate of pH fall and lower water holding capacity as well as ham with higher weight losses in salting and greater incidence of defects in the dry-cured product. There were insignificant interactions between halothane genotype and loading method or stocking density. Overall, irrespective of pre-slaughter treatment, the Nn pigs were less suitable for the production of high quality products such as dry-cured ham.     

Glycogen content, buffering capacity and resting pH in live muscles of pigs of different halothane genotypes (a pilot project)

The development of PSE (pale, soft and exudative) meat is characterized by a rapid decrease in pH post-mortem and/or a low ultimate pH. We investigated some physiological properties of the live muscle (the glycogen content, the non-bicarbonate buffering capacity and 'resting pH'), which could influence both the decrease in pH and the ultimate pH. Measurements were performed on three halothane genotypes, hal(N)hal(N), hal(N)hal(n) and hal(n)hal(n), with their known predispositions for PSE meat. It was demonstrated that the glycogen content in both the groups of double recessive and heterozygous individuals was higher than the levels in the group of homozygous dominant pigs. No difference was found in non-bicarbonate buffering capacity between the groups. The groups with the highest glycogen levels also had the lowest 'resting pH' values. The results indicate that measurement of glycogen content in vivo may be superior to the halothane test in detecting PSE-prone individuals. The lower pH values of carriers of the hal(n) gene further indicate that the characteristic rapid decrease after slaughter may not be as fast as generally accepted, as even very low pH values can be observed in the muscles of live pigs.     

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.     

The intravenous halothane test as an experimental method for quantifying stress sensitivity in pigs

The venous blood pH, pCO₂, lactate, pyruvate and haematocrit responses to an intravenous (i/v) infusion of halothane-lipid emulsion were assessed in Pietrain, Pietrain X Norwegian Landrace and Gloucester pigs. Halothane-induced lactacidosis was dose related in the Pietrain (stress sensitive) pigs between 0 and 82 μl halothane kg^?-1, whereas the crossbred and Gloucester pigs did not show any lactacidosis. It is concluded that the i/v halothane test can be used to quantify a stress sensitive pig's reaction to the drug, and that the crossbred pig does not express halothane sensitivity even at a mild level. Carazolol pretreatment in Pietrain pigs increased the halothane-induced lactacidosis, whereas in a separate study carazolol was found to decrease their rate of post-mortem muscle acidification. This indicates that halothane activates a different mechanism from stress when inducing lactacidosis in stress sensitive pigs.     

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

The three halothane genotypes (NN, Nn, and nm) were identified by measuring the capacity for Ca²⁺ accumulation by sarcoplasmic reticulum in whole muscle homogenate preparations of M. longissimus dorsi with a Ca²⁺ specific electrode at 35°C. Significant differences (P < 0·001) in deterioration (%) of Ca²⁺ accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed after ageing the whole muscle homogenate preparations for 24 h in ice.

Predictions of meat quality in live pigs (n = 34) based on the values for water-holding capacity, assessed as fluid (g/0·5 g wet wt LD), and pH (fluid) by using small biopsy LD samples (Cheah et al. 1993) were performed on all the halothane genotypes. The halothane genotype NN (n = 11) showed a fluid value of 0·37 ± 0·01 and a pH (fluid) value of 6·62 ± 0·03 as compared with 0·61 ± 0·02 and 5·84 ± 0·04, respectively, for the halothane genotype nn (n = 13). The Nn pigs (n = 10) showed fluid (0·49 ± 0·03) and pH (fluid) (6·19 ± 0·11) values between those values observed for the two homozygotes (NN and nn). Predictions of meat quality in live pigs from biopsy LD muscles were confirmed from assessments on post-mortem LD muscles based on pH₁ and fibre optic probe (FOP) measurements.

The extent of deterioration (%) in Ca²⁺ accumulation showed high correlations with fluid (r = −0·861) and pH (fluid) (r = −0·831) in the biopsy LD samples, and with pH₁ (r = 0·663), FOP (r = −0·812), and drip (%) loss (r = −0·777) in the post-mortem LD samples.     

Predictive value of slaughterhouse measurements of ultimate pork quality in seven halothane negative Yorkshire populations

An experiment with 1969 pigs, belonging to Yorkshire sire lines, was set up in cooperation with seven Dutch breeding organizations. The pigs, which were claimed to be halothane negative, were slaughtered in weekly batches. Light reflectance was determined with the Hennessy Grading Probe (HGP) and Fibre Optic Probe (FOP), in addition to pH(1) and rigor mortis at 45 min post mortem (p.m.). Further meat quality determinations were performed either in the slaughterhouse at 20 h p.m., or in the laboratory at 24 h p.m.. At first sight, both the scatter of light (HGP-PSE, FOP) and pH, measured at 45 min p.m., appeared to be indicative of the ultimate meat quality score. More accurate analyses, however, showed that the value of reflectance values is limited and less suitable in comparison to pH(1), especially with reference to the prediction of ultimate quality characteristics of water holding capacity. The correlations for pH(1) with drip loss were rather consistent, ranging from -0·34 to -0·52 per breeding population. In contrast, HGP-reflectance values ranged from -0·27 to 0·34, while those based on FOP(1) had a range from nearly zero (0·02) to 0·20. The proportion of variation (R(2) × 100%) in drip loss, explained by a set of slaughterline measurements, ranged from 13 to about 28% per breeding population. The use of measurements carried out at 20 h p.m. improved the R(2) × 100% for drip loss to a range from 50 to 62%.     

Effects of the stunning procedure and the halothane genotype on meat quality and incidence of haemorrhages in pigs

A total of 313 pigs (127 halothane-free, NN, and 186 heterozygous halothane, Nn) were slaughtered in four batches at two commercial abattoirs with two different stunning systems, an automatically head-only followed by head-to-chest electrical stunner and a compact carbon dioxide (CO(2)) stunning unit. Meat quality on the loin muscle was assessed by measuring electrical conductivity (PQM) and colour (Minolta CR 200) at 7 h post mortem, and ultimate pH. Loins showing PQM >6.0 μs were classified as clearly pale, soft and exudative (PSE) meat. The incidence of petechiae, ecchymosis and haematomas in the shoulders, loins and hams was also evaluated. In the abattoir equipped with the electrical stunning system, a higher incidence of potentially PSE meat was found compared with the abattoir equipped with CO(2) stunning (35.6 vs. 4.5%). Likewise, electrical stunning increased significatively the incidence of petechiae in the loins, shoulders and hams, and ecchymosis in the loins and hams. Also, the incidence of PSE meat was higher in the Nn pigs compared with NN pigs (24.7 vs. 7.9%). It is suggested that for improving meat quality and reducing incidence of haemorrhages electrical stunning should be avoided. Further improvements in meat quality can be achieved by eliminating the halothane gene specially in CO(2)-stunned pigs.     

Meat quality characteristics in different lines of Iberian pigs

Physico-chemical parameters involved in technological meat quality for dry cured processing of four different lines (Entrepelado, Lampi?o, Retinto and Torbiscal) of Iberian pigs were studied in the Masseter (MS) and Longissimus dorsi (LD) muscles. The line of Iberian pig significantly affected intramuscular fat content of MS muscle, animals from the Torbiscal line showing lower values. Proportions of several fatty acids of total lipids and polar lipids from the MS muscle were also affected. However, fatty acid composition and total lipids, neutral lipids and polar lipids of LD muscle and neutral lipids of MS muscle were scarcely affected. Lipid oxidation was also unaffected by Iberian pig line, but instrumental colour parameters of MS muscle showed significant variations.     

Pregnancy rate in dairy cows inseminated on the basis of electronic probe measurements.

A new vaginal probe with two pairs of parallel electrodes 90 degrees apart was designed with a switching arrangement so that electrical resistance (ohms) of the dorsal and the ventral areas of the anterior vagina could be monitored separately during the estrous cycle. Three inseminators probed cows during February--April, 1977, in nine herds in stanchion barn housing. Cows not seen in estrus by 40 to 60 dyas after calving were probed every 3rd day. At each dairyman's option normal cows with a low porbe reading were inseminated. Controls consisted of cows seen in estrus by the dairyman and reported for insemination in the routine manner. The diagnosed pregnancy rate for 86 first service controls was 49% versus 52% for 58 cows not seen in estrus, but identified by low probe readings. Cows varied in electrical resistance at breeding, but the fact that pregnancy rates were equivalent in the two groups is interpreted to mean that the probe was as effective in identifying cows suitable for insemination as was visual observation of estrus by dairymen.     

Plasma and muscle cortisol measurements as indicators of meat quality and stress in pigs

Post-slaughter blood samples and muscle samples were collected from pigs slaughtered at the completion of a live-animal performance trial. There were two lines of pigs in which the halothane allele (n) was segregating. The lines were a lean line selected for rapid lean growth and an unselected fat line. There were homozygous normal (NN), homozygous halothane positive (nn) and heterozygous (Nn) genotypes in both lnes. Cortisol was measured in the plasma of the blood samples and in muscle juice obtained by high-speed centrifugation. Meat quality was assessed using pH, colour, fibre-optic probe, drip loss and cure yield measurements. Plasma cortisol concentrations in the fat line were significantly (P < 0·05) greater than thosein the lean line but concentrations did not differ significantly for the three halothane genotypes. Carcasses classified as dark, firm and dry (DFD) had significantly (P < 0·05) greater muscle cortisol concentrations than those classified as normal. Plasma and muscle cortisol concentrations of carcases classified as pale, soft and exudative (PSE) did not differ significantly from those classified as normal. Correlations between muscle cortisol and meat quality attributes were generally highly significant (r = 0·31 to r = 0·51, P < 0·001) There was a highly significant correlation (r = 0·73, P < 0·0001) between plasma and muscle cortisol concentrations.     

Characterization of antimicrobial-resistant phenotypes and genotypes among Salmonella enterica recovered from pigs on farms, from transport trucks, and from pigs after slaughter

The main objectives of this study were to determine antimicrobial resistance patterns among Salmonella serotypes and to evaluate the role of transport trucks in dissemination of antimicrobial-resistant strains of Salmonella. Salmonella from groups of nursery and finishing pigs on farms, from trucks, and from pigs after slaughter were compared using serotyping, patterns of antimicrobial resistance, and pulsed-field gel electrophoresis patterns. The five farms included in the study yielded 858 isolates representing 27 Salmonella serovars. The most common resistance observed (80% of all isolates) was to tetracycline; resistance to ampicillin (42%), chloramphenicol (31%), amoxicillin/clavulanic acid (30%), and piperacillin (31%) also were common. We found a correlation between serovar and antimicrobial resistance. High correlation was found between Salmonella Typhimurium var. Copenhagen and chloramphenicol resistance (Spearman rank correlation, rho = 0.7). Multidrug resistance was observed primarily in Salmonella Typhimurium var. Copenhagen (94%) and Salmonella Typhimurium (93%) and was much less common in the other common serovars, including Salmonella Derby (7%) and Salmonella Heidelberg (8%). Of the 225 isolates exhibiting the most common pentaresistance pattern in this study, amoxicillin/clavulanic acid-ampicillin-chloramphenicol-piperacillin-tetracycline, 220 (98%) were Salmonella Typhimurium var. Copenhagen, and 86% of the isolates of this serovar had this pattern. Isolates from the trucks were similar, based on pulsed-field gel electrophoresis patterns, to those from the cecum and mesenteric lymph nodes of pigs on two of the farms, suggesting the probable infection of pigs during transport. Class I integrons were also common among various serovars.