Culture results from wound biopsy versus wound swab: does it matter for the assessment of wound infection?

OBJECTIVES: The aim of this study was to determine whether assessment of wound infection differs when culture results from wound biopsy versus wound swab are available in clinical practice. METHODS: For 180 eligible patients, a swab and biopsy were taken from one wound during a regular appointment at a wound care facility in eastern Netherlands. Culture results from both methods were supplemented with clinical information and provided to a panel of six experts who independently assessed each wound as infect or not, separately for swab and biopsy. Assessments for biopsy and swab were compared for the complete expert panel, and for individual experts. RESULTS: The complete expert panel provided the same wound assessment based on (clinical information and) culture results from wound biopsy and wound swab in 158 of 180 wounds (87.8%, kappa 0.67). For individual experts, agreement between biopsy and swab varied between 77% and 96%. However, there were substantial differences between experts: the same assessment was provided in 62 (34.4%) to 76 (42.2%) wounds for swab and biopsy respectively. CONCLUSIONS: Assessment of infection does not significantly differ when culture results from swabs or biopsies are available. The substantial variability between individual experts indicates non-uniformity in the way wounds are assessed. This complicates accurate detection of infection and comparability between studies using assessment of infection as reference standard.

Hepatic expression patterns in psychosocially high-stressed pigs suggest mechanisms following allostatic principles.

Psychosocial challenges are known to introduce cellular and humoral adaptations in various tissues and organs, including parts of the sympatho-adrenal-medullary system and hypothalamic-pituitary-adrenal axis as well as other peripheral tissue being responsive to cortisol and catecholamines. The liver is of particular interest given its vital roles in maintaining homeostasis and health as well as regulating nutrient utilization and overall metabolism. We aimed to evaluate whether and how response to psychosocial stress is reflected by physiological molecular pathways in liver tissue. A pig mixing experiment was conducted to induce psychosocial stress culminating in skin lesions which reflect the involvement in aggressive behavior and fighting. At 27 weeks of age, animals prone to psychosocially low- and high-stress were assigned to mixing groups. Skin lesions were counted before mixing and after slaughter on the carcass. Individual liver samples (n=12) were taken. The isolated RNA was hybridized on Affymetrix GeneChip porcine Genome Arrays. Relative changes of mRNA abundances were estimated via variance analyses. Molecular routes related to tRNA charging, urea cycle, acute phase response, galactose utilization, and steroid receptor signaling were found to be increased in psychosocially high-stressed animals, whereas catecholamine degradation and cholesterol biosynthesis were found to be decreased. In particular, psychosocially high-stressed animals show decreased expression of catechol-O-methyltransferase (COMT) which has been linked to molecular mechanisms regulating aggressiveness and stress response. The expression patterns of high-stressed animals revealed metabolic alterations of key genes related to energy-mobilizing processes at the expense of energy consuming processes. Thus, the coping following psychosocial challenges involves transcriptional alterations in liver tissue which may be summarized with reference to the concept of allostasis, a strategy which is critical for survival.

Prediction of pork quality with near infrared spectroscopy (NIRS) 2. Feasibility and robustness of NIRS measurements under production plant conditions.

Longissimus dorsi samples (685) collected at four processing plants were used to develop prediction equations for meat quality with near infrared spectroscopy. Equations with R(2)>0.70 and residual prediction deviation (RPD)≥2.0 were considered as applicable for screening. One production plant showed R(2) 0.76 and RPD 2.05, other plants showed R(2)<0.70 and RPD<2.0 for drip loss %. RPD values were ≤2.05 for drip loss%, for colour L*≤1.82 and pH ultimate (pHu)≤1.57. Samples were grouped for drip loss%; superior (<2.0%), moderate (2-4%), inferior (>4.0%). 64% from the superior group and 56% from the inferior group were predicted correctly. One equation could be used for screening drip loss %. Best prediction equation for L* did not meet the requirements (R(2) 0.70 and RPD 1.82). pHu equation could not be used. Results suggest that prediction equations can be used for screening drip loss %.

Prediction of pork quality with near infrared spectroscopy (NIRS): 1. Feasibility and robustness of NIRS measurements at laboratory scale.

The objective was to study prediction of pork quality by near infrared spectroscopy (NIRS) technology in the laboratory. A total of 131 commercial pork loin samples were measured with NIRS. Predictive equations were developed for drip loss %, colour L*, a*, b* and pH ultimate (pHu). Equations with R(2)>0.70 and residual prediction deviation (RPD)≥1.9 were considered as applicable to predict pork quality. For drip loss% the prediction equation was developed (R(2) 0.73, RPD 1.9) and 76% of those grouped superior and inferior samples were predicted within the groups. For colour L*, test-set samples were predicted with R(2) 0.75, RPD 2.0, colour a* R(2) 0.51, RPD 1.4, colour b* R(2) 0.55, RPD 1.5 and pHu R(2) 0.36, RPD 1.3. It is concluded that NIRS prediction equations could be developed to predict drip loss% and L*, of pork samples. NIRS equations for colour a*, b* and pHu were not applicable for the prediction of pork quality on commercially slaughtered pigs.

Pigs' aggressive temperament affects pre-slaughter mixing aggression, stress and meat quality.

Pre-slaughter stress has a negative impact on animal welfare and on meat quality. Aggressive behaviour when pigs are mixed together for transportation to, or on arrival at, the abattoir is an important factor in pre-slaughter stress. Aggressiveness of pigs varies between individuals in the population, and this study investigated its effects on stress and meat quality at slaughter. We mixed pigs at a young age to identify individuals of high (H) or low (L) aggressive temperament using the previously validated approach of lesion scoring. To contrast extremes of social stress single-sex groups of eight pigs were mixed according to their aggressiveness in HH, HL or LL combinations or left unmixed (U) prior to transport and slaughter (n = 271). Each treatment was replicated in at least two groups in each of four slaughter batches. Mixing per se had little effect, but mixed groups composed of aggressive pigs (HH) had more carcass skin lesions and higher levels of plasma cortisol at slaughter and had loin muscle samples with higher pH at 24 h, and lower redness (a*) and yellowness (b*) compared to the other treatments. Females had higher levels of plasma cortisol at slaughter, a more rapid decline in pH post-slaughter and greater lean content of meat. Lactate and creatine kinase (CK) levels and meat pH were affected by the interaction of sex and treatment. Genetic factors, dam and sire line composition, and halothane locus (ryanodine receptor 1, RYR1) genotype, also affected a number of production and meat quality parameters as expected. Additionally, 'commercially normal' levels of social stress were studied in four further slaughter batches with no manipulation of group composition (n = 313). In these pigs, the proportion of unfamiliar pigs and group size of lairage groups explained limited variation in lesion scores at slaughter, but earlier aggressiveness did not. High numbers of skin lesions on the carcass were associated with high levels of cortisol and lactate and low glucose at slaughter, but not with meat quality measures. When stress and meat quality measures were compared for all pigs, high lactate was associated with low early pH and high drip loss, while high cortisol and CK were associated with high pH at 24 h and changes in meat colour. In conclusion, mixing pigs of above average aggressiveness resulted in greater aggression and stress, and changes in meat quality parameters, consistent with the effects of pre-slaughter stress on muscle chemistry.

Primary hepatic invasive aspergillosis with progression after rituximab therapy for a post transplantation lymphoproliferative disorder.

We present a case of primary hepatic and possible splenic invasive aspergillosis (IA), which progressed under anti-CD20 B cell treatment for posttransplantation lymphoproliferative disease following allogeneic stem cell transplantation, to highlight the clinical value of a positive galactomannan-antigen test, an intestinal portal of entry of Aspergillus, and the detrimental effect of B lymphocyte depletion in IA.

Quality pork genes and meat production.

Functional genomics, including analysis of the transcriptome and proteome, provides new opportunities for understanding the molecular processes in muscle and how these influence its conversion to meat. The Quality Pork Genes project was established to identify genes associated with variation in different aspects of raw material (muscle) quality and to then develop genetic tools that could be utilized to improve this quality. DNA polymorphisms identified in the porcine PRKAG3 and CAST genes illustrate the impact that such tools can have in improving meat quality. The resources developed in Quality Pork Genes provide the basis for identifying more of these tools.

Effects of housing conditions of slaughter pigs on some post mortem muscle metabolites and pork quality characteristics.

The results of two experiments studying the effects of housing conditions on post mortem muscle metabolism and meat quality are presented. In the first experiment slaughter pigs (n=71) from two different crossings, were raised at a density of 0.7 m(2)/animal (10 pigs/pen) either with (enriched) or without (conventional) a bedding of daily fresh straw. In the second experiment, animals (n=60) were reared under either conventional or free range housing (1.25 m(2)/animal, 30 pigs per pen) conditions. Main differences between conventional and enriched housed pigs were found in the biceps femoris (BF) muscle, and related to temperature, drip loss and colour. Association studies revealed that there were significant correlations between early (0-4 h) post mortem muscle pH and glycogen and lactate concentrations and between muscle pH measured at 1 h post mortem and muscle rigidity, expressed as the rigor value. There were significant differences with respect to meat quality and post mortem metabolism of the longissimus lumborum (LL), between conventional and free-range pigs. Early post mortem pH (0-4 h) was highest in the free-range pigs, due to low lactate concentrations. The relatively fast pH decline in the conventionally housed group resulted in increased amounts of water exuding from the meat, as measured by the filter paper method. The ultimate pH, was lowest in the free-range animals. The differences in ultimate pH, however, had no effect on drip or cooking losses. It can be concluded from these results that enrichment of the housing system has little effect on the course of the post mortem metabolism and meat quality. However, increasing the freedom of movement by applying lower stocking densities, affects the post mortem muscle metabolism, resulting in reduced water exudation. Correlations up to 0.7 between energetic parameters are not sufficiently high to be useful to predict meat quality of individual carcasses.

Critical assessment of issues in the diagnosis of invasive aspergillosis.

Invasive aspergillosis remains a devastating disease, which is partly because of the inability to identify infected patients at an early stage of the disease. Recently, new diagnostic tests and procedures have been developed to help in identifying high-risk patients. High-resolution computed tomography has been shown to be a potent tool for detecting pulmonary abnormalities in neutropenic patients. Assays for the detection of circulating markers such as fungal antigens or Aspergillus DNA have been developed and show that markers can be detected in the blood at an early stage of infection. Also, the markers correlate with the fungal burden in the tissue, which allows monitoring of response to antifungal therapy. The tests and procedures that are now available need to be incorporated into management strategies for at-risk patients and evaluated in clinical trials. Although we now have markers that allow the early detection of fungal products, many questions remain unanswered with respect to the kinetics of the markers in different patient groups, the optimal management strategy and the effect of prophylaxis and treatment on the markers. Nevertheless, the implementation of new approaches for the management of invasive aspergillosis offers opportunities to improve outcome of patients.

Relationships between behavioral and meat quality characteristics of pigs raised under barren and enriched housing conditions.

In this study the effects of barren vs enriched housing conditions of pigs on their behavior during the lairage period (2-h holding period before slaughter), carcass characteristics, postmortem muscle metabolism, and meat quality were studied. The barren housing system was defined by common intensive housing conditions (i.e., with slatted floors and recommended space allowances), whereas the enriched environment incorporated extra space and straw for manipulation. Salivary cortisol concentrations were measured before transport and at the end of the lairage period. During the lairage period the percentage of time spent walking and fighting by the pigs was registered. Carcass characteristics such as weight, meat percentage, and backfat thickness were determined. At 5 min, 45 min, 4 h, and 24 h postmortem, pH, temperature, and lactate concentrations were determined in the longissimus lumborum (LL) and biceps femoris (BF) muscles. Capillarization of the muscle, mean muscle fiber area, and color and drip loss after 2 and 5 d of storage were determined for both muscle types. Pigs from the barren environment had a significantly higher increase in cortisol from farm to slaughter, but no differences in behavior were observed during the lairage period. Carcass characteristics did not differ between pigs from barren and those from enriched housing conditions. Postmortem lactate formation was significantly lower in LL muscles of enriched pigs at 4 and 24 h postmortem. Capillary density and mean muscle fiber area did not differ between the groups of pigs. The percentage of drip loss at 2 and 5 d after storage of LL muscle samples from enriched-housed pigs was significantly lower than that of the barren-housed pigs. Similar tendencies were found for the BF muscle from pigs kept in an enriched environment, but these were not statistically significant. The housing system did not affect meat color. It is concluded that on-farm improvement of animal welfare by environmental enrichment can also lead to beneficial economic effects after slaughter by improving the water-holding capacity of pork.

Instrumental colour classification of veal carcasses.

Three experiments, involving over 56 000 veal carcasses, were carried out to develop a method for instrumental colour classification of veal carcasses at 45 min post mortem with the Minolta CR300. The method should produce results similar to those of the 10-point colour-system, which is currently in use in The Netherlands. In the first experiment, the colour of veal carcasses was visually assessed by three observers and instrumentally measured with two Minolta CR300 devices. The average of the results of the three observers and the two Minolta devices were used for discriminant analysis to analyse yield classification rules, which allowed to assignment of the carcasses to classes of the 10-point colour-system. Identical classifications for Minolta and observer were obtained for 63.2% of the carcasses. In the second and third experiment, the classification rules with the Minolta CR300 were used to predict the colour class. For the new samples, identical classification results were obtained for 50-55% of the carcasses. In 41-44% of the carcasses the classification results differed by less than one class. The results show that the Minolta CR300 is under practical conditions able to predict the 10-point colour classes and can be used for on-line colour classification in a slaughterhouse.

Effects of rate of pH fall, time of deboning, aging period, and their interaction on veal quality characteristics.

Three groups of veal carcasses were selected on the basis of their pH in the longissimus lumborum muscle at 3 h postmortem (pH3) to study the effects and interaction with time of deboning on quality characteristics of veal. The following groups of 10 calves each were selected: 1) fast pH fall, pH3 < 6.2; 2) intermediate pH fall, 6.2 < pH3 < 6.7; and 3) slow pH fall, pH3 > 6.7. Longissimus thoracis et lumborum (LTL) muscles of sides of the selected carcasses were randomly assigned to be excised at either 24 or 48 h postmortem. Color, water-holding capacity, and shear force measurements were determined after an aging period of 2, 3, 4, 7, and 14 d, respectively. Color of longissimus muscle samples from veal calves with similar preslaughter blood hemoglobin values becomes significantly lighter with a faster pH fall. Muscle color was not affected by time of deboning and overall color of all longissimus samples remained stable during storage and was not affected by rate of pH fall and time of deboning. Cooking losses increased with both a faster rate of pH fall and by deboning at 24 h postmortem. Drip losses during vacuum storage were higher for muscles excised at 24 rather than 48 h postmortem. Both when deboned at 24 and 48 h, postmortem veal carcasses with a lower rate of pH fall had higher shear force (SF) values than did carcasses with a higher rate of pH fall. Deboning at 24 h postmortem resulted in higher SF values than deboning at 48 h postmortem. Differences in SF between 24- and 48-h deboning were larger in slower glycolyzing carcasses. Aging improved tenderness but did not fully reduce the difference in SF values between 24- and 48-h deboning. The results suggest that deboning of veal carcasses before the ultimate pH has been reached may result in muscle contraction, which may exert negative effects on tenderness and water-holding capacity of veal. Effects of time of deboning can, at least partly, be explained by differential effects on shortening of the muscle fibers.

The effects of selection of pigs on growth rate vs leanness on histochemical characteristics of different muscles.

The microstructure of two type of muscles was studied in a selection experiment conducted with Dutch Large White pigs (boars and gilts) selected for either low backfat thickness (L-line) or fast growth (F-line). Second- and fourth-generation pigs were used to determine effects of selection on fiber type composition, fiber area, and capillary density in the longissimus lumborum (LL) and biceps femoris (BF) muscles. Immediately after slaughter samples were taken from the LL and BF muscles. The latter was divided into an inside (BFi) and outside (BFo) portion, which refer to the red and white portions of the biceps femoris. Serial sections were stained for ATPase (pH 4.60), succinate dehydrogenase (SDH), and alpha-amylase-periodic acid shiff (PAS) to determine fiber type and capillary density. The LL and BFo muscles had predominantly type IIBw fibers, whereas the BFi muscle had a 2 to 4 times higher amount of type I fibers. In most muscles there were more type I and fewer type IIBw fibers in F- than in L-line pigs (P < .05), except in the LL muscle of second-generation pigs and in the red part of the BF muscle of fourth-generation pigs. In both selection lines lower type I and higher type IIBw percentages were found in muscles from gilts than in those from boars (P < .05). Capillary density and fiber area of L- and F-lines showed minor differences, which could be explained by differences in weight and age of the pigs of both lines. The results suggest that selection for low backfat thickness in pig breeding compared with increased growth rate resulted in fewer oxidative and more glycolytic muscle fibers. The magnitude of the effect depended on muscle type and duration of the selection period.

Fibre area and capillary supply in broiler breast muscle in relation to productivity and ascites.

The objective in this study was to examine the capillary supply in the broiler breast muscle in relation to productivity and the incidence of ascites. Muscle samples (pectoralis superficialis) were collected from 24 pairs of broilers of a commercial paternal strain. The pairs consisted of full sib broilers (brothers and sisters). Of each pair one broiler had a high arterial pressure index, as an indication of ascites, and the other was a healthy chick of the same sex. Data collected were, among others, body weight, arterial pressure index, haematocrit and weight of breast muscle and lungs. Pectoral muscle samples were histologically analysed with respect to capillary density, fibre area and number of capillaries per fibre. Ascitic chickens (measured as high values for heart hypertrophy) had a lower number of capillaries per fibre and tended to have reduced fibre area, although they had a similar capillary density in the pectoral muscle in comparison with healthy chickens. The expected increase in capillary density was not observed. Normally capillary densities decrease in proportion to the increase in fibre size. So ascites has unfavourable relations with capillary traits. Fast growth was not significantly associated with capillary density. However, chickens with a higher percentage breast muscle had a lower capillary density. This implies that high muscularity might be a risk for a diminished oxygen supply to the breast muscle.

Effect of dietary vitamin E supplementation on beef colour stability.

The effect of dietary vitamin E upon colour, waterholding capacity, bacterial growth and lipid oxidation of beef longissimus thoracis (LT) and psoas major (PM) muscle were examined during aerobic display of fresh muscle and after aging in vacuum for 26 days. Forty crossbred beef bulls received a whole crop corn silage, supplemented with concentrate. Twenty bulls were each supplemented with 2025 mg vit E per day (added to the concentrate) for 136 day prior to slaughter and compared with non-supplemented control animals (n=20). In fresh LT muscle drip loss did not differ between treatment groups, while in PM muscle drip loss was significantly higher for the supplemented group. The treatment did not affect bacterial growth in fresh and aged muscles. Lipid oxidation during 12 day storage of fresh muscle was significantly lower for the supplemented group, as indicated by the lower TBA-values. No effect of the vitamin E treatment was observed on a (∗)-values of both fresh and aged LT muscle during display for 8 and 5 days, respectively. In PM muscle, supplemented beef had lower a (∗)-values in fresh (at day 1) and aged (at days 1 and 2) muscle, due to a lower oxygenation. The reason for this lower oxygenation is unclear. After aging, colour stability was decreased and more variable than in fresh muscle. Similar results were obtained when the difference in reflection values at 630 and 580 nm (R630-580), instead of the a (∗) value, was used as a parameter for colour stability. The absence of an effect of vit. E on the rate of discoloration, might possibly be explained from the observation that α-tocopherol levels in control muscle were relatively high (LT: 2.1 and PM: 3.2 µg/g muscle), compared with data from literature. Analysis of the feed for vit. E suggests that this was due to a relatively high natural vit. E uptake from the feed, which was calculated to be approx. 330 mg vit. E per animal per day for the control group.

Post-mortem variation in pH, temperature, and colour profiles of veal carcasses in relation to breed, blood haemoglobin content, and carcass characteristics.

A total of 1764 male calves of the Meuse-Rhine-Yssel (MRY) and Friesian-Holstein (FH) breeds were slaughtered at two commercial slaughterhouses to investigate the variation in pH, temperature, and colour of Dutch veal carcasses processed without electrical stimulation and with a moderate chilling regimen (average temperature of the longissimus lumborum muscle at 45 min, 3, 24, and 48 h post-mortem was 38.4, 23.3, 3.7 and 1.9°C, respectively). Blood haemoglobin content was determined 2 weeks before slaughter. The efficacy of captive bolt stunning was scored and the carcass movements after shackling registered. Temperature and pH measurements were carried out at 45 min, and 3, 24, and 48 h after slaughter in the longissimus lumborum muscle (LL). Muscle surface colour (CieLAB-values) was measured with a colorimeter at the rectus abdominis muscle at the same times post-mortem. Carcass conformation and visual carcass colour classification were determined at 45 min post-mortem. Carcasses with a better EUROP-conformation score and heavier weight showed a higher rate of pH decline and a slower cooling rate. Slight differences in cooling systems between the slaughterhouses caused marked differences in pH and temperature profiles. Significant differences in carcass weight were observed between the MRY and FH breeds, leading to significant differences in pH and temperature profiles. Carcass colour of the two breeds was similar. Veal carcass colour in general was not related to the observed variation in post-mortem pH and temperature in the longissimus lumborum muscle and was shown to be more associated with the blood haemoglobin content. Haemoglobin content of the blood in the period before slaughter was shown to be related to the visually assessed carcass colour at 45 min post-mortem (using a 10-colour scale), as well as to the instrumentally determined L*-value, with significant correlation coefficients of 0.61 and -0.61, respectively. Repeated captive bolt stunning to obtain unconsciousness significantly decreased pH at 3 h post-mortem. The degree of carcass movement after slaughter did not influence pH, temperature, or colour profiles of the carcasses.

Muscle fibre type and meat quality.

Muscle morphology and fibre type composition are briefly reviewed in relation to colour stability and tenderness in beef, and water holding capacity, colour and eating quality in pork. A large inter-muscle and inter-animal variation exists in meat quality, which is often related to metabolic and contractile properties as determined by their muscle fibre type distribution. Characteristics of different muscles may be modified in living animals by environmental conditions and genetic selection. Selection experiments based on biochemical and histochemical characteristics determined in biopsies or otherwise, and study of correlated selection responses, may lead to the development and applications of (new) muscle traits in future breeding programmes.

Variation in post-mortem rate of glycolyis does not necessarily affect drip loss of non-stimulated veal.

In this study the effect of the rate of post mortem pH fall on the water-holding capacity of meat from moderately chilled veal carcasses was investigated. Also the relationship between muscle protein denaturation and drip loss of veal was examined. Three groups of 10 Friesian Holstein male veal calves each were selected on the basis of their pH in M. longissimus thoracis et lumborum (LTL) at 3 hr post mortem (pH(3)): (1) fast pH-fall, pH(3) < 6.2; (2) intermediate pH-fall, 6.5 < pH(3) < 6.6; (3) slow pH-fall, pH(3) > 6.7. After 48 hr of chilling the LTL was excised from the carcass and sampled for determination of drip loss, filter paper wetness, sarcomere length, protein solubility and transmission value. Differences in pH(3) were not associated with differences in drip loss, filter paper wetness or differences in protein denaturation. It is suggested that at the relatively high veal carcass chilling rate the effect of rate of pH-fall on protein denaturation and thus on drip loss is negligible. Drip loss of veal was highly correlated with both solubility of sarcoplasmic (r = -0.67; p < 0.001) and total muscle protein (r = -0.54; p < 0.01) and with transmission values (r = 0.66; p < 0.001). These results indicate that protein denaturation measurements may be a good predictor for drip loss of veal.

Effects of preslaughter muscle exercise on muscle metabolism and meat quality studied in anesthetized pigs of different halothane genotypes.

The influence of preslaughter muscle activity was studied on porcine muscle metabolism and meat quality, whereas other stress factors were minimized. Muscle exercise was stimulated by electrical pulses in anesthetized pigs of different halothane genotypes (NN, Nn, nn). A part of the LM and SM was stimulated during the last 15 min of a 45-min period of anesthesia. The contralateral part of each muscle was taken as a non-stimulated control. Antemortem blood and muscle biopsy samples were taken to study the muscle energy metabolism by measuring different metabolites. The same metabolites and certain meat quality characteristics were determined after slaughter. Stimulated muscle exercise led to lower (P < .01) antemortem glycogen and creatine phosphate concentrations and increased (P < .01) lactate and creatine values in pigs of all halothane genotypes. No difference was seen between the three halothane genotypes in the measured glycogen breakdown just before slaughter. Postmortem glycolysis differed between pigs of different halothane genotypes. This resulted in lower (P < .05) glycogen and creatine phosphate values and higher (P < .05) lactate and creatine concentrations for nn pigs than for NN pigs, with intermediate metabolite concentrations for Nn pigs. Water-holding capacity was lower (P < .05) in exercised muscles of NN and Nn pigs than in the muscles of controls. Meat color was only lighter (P < .05) after muscle stimulation in NN pigs. The exercise did not deteriorate the already light color and lower water-holding capacity in nn pigs. Muscle pH can already be low at slaughter and is not only the result of an increased postmortem glycolysis. Preslaughter muscle exercise is relatively more important in determining meat quality from NN and Nn pigs.

Influence of preslaughter muscle temperature on muscle metabolism and meat quality in anesthetized pigs of different halothane genotypes.

Preslaughter muscle temperature in anesthetized pigs of different halothane genotypes (NN, Nn, and nn) was raised or lowered during a 45-min period of anesthesia. The different treatments produced muscle and rectal temperature differentials of 1.5 to 2 degrees C across genotypes. Blood and muscle biopsy samples were taken during the period of anesthesia, to study muscle energy metabolism by measuring different metabolites. After slaughter, the same metabolites and some meat quality characteristics were determined. An increased muscle temperature resulted in lower (P < .01) glycogen concentrations at slaughter and an increased (P < .05) glycogen, creatine phosphate, and ATP breakdown after slaughter in the muscles of these two halothane genotypes. However, the muscle metabolism of NN pigs was not affected by a higher temperature. The muscle metabolism of Nn pigs was more similar to that of NN pigs at low preslaughter temperatures. Elevated temperatures shifted the muscle metabolism of Nn pigs toward that of nn pigs. Water-holding capacity was lowered (P < .01) in all halothane genotypes due to elevated preslaughter muscle temperatures. It was concluded that increases in preslaughter muscle temperature are, in addition to an effect of preslaughter stress conditions, also a causative factor in enhancing ante- and postmortem muscle metabolism. This effect was more pronounced in Nn and nn pigs. Meat quality was influenced negatively in all genotypes by an increased muscle temperature, but more in NN and Nn pigs than in nn pigs. Lowering preslaughter muscle temperatures had the greatest advantage of improving meat quality in NN and Nn pigs.