Effect of early post-mortem cooling on temperature, pH fall and meat quality in pigs

The aim of this study was to investigate how early cooling of carcasses after slaughter by showering with cold water affected the rate of the pH fall post mortem, protein denaturation and drip loss. Eighty pigs were selected in pairs at debleeding according to sex and farm of origin. All pigs were halothane genotyped and glycolytic potential in LD analysed. One of each pair was cooled 30 min post mortem by showering with 10-12 °C water for 12 min. The control pig was treated normally except for the same delay before batch chilling commenced. The initial pH fall in LD and BF did not depend on the glycolytic potential in LD but at 5 to 6 and 24 hr post mortem pigs with the lowest glycolytic potential had the highest pH. Weight and lean meat content did not affect the cooling curve, i.e. the temperature fall. The results showed that it was possible to reduce the temperature in BF and LD by cooling at slaughter. The maximum difference in temperature between control and cooled carcasses 2hr post mortem was 2 and 1 °C in LD and BF respectively. The lowering of the muscle temperature early post mortem resulted in a reduced rate of the pH fall and a higher pH from 2 to 6 hr in the cooled carcasses. The rate of the pH fall in LD and BF seemed to be independent of temperature at levels above approximately 37 °C, but decreased linearly as the temperature dropped below approximately 37 °C. The cooling procedure used here did not result in a significant reduction in protein denaturation or drip loss, although there was a tendency towards lower drip loss in LD and BF in cooled carcasses.     

Comparison of Dehiding versus Scalding and Singeing: Effect on Temperature, pH and Meat Quality in Pigs

The aim of this work was to investigate the temperature and pH changes taking place at the slaughter line and during the chilling process, and the subsequent effect on meat and eating quality in pig carcasses that had either been scalded and singed or dehided. Both processes were followed by fast chilling. 219 halothane-gene-free Duroc Sire and Landrace-Yorkshire pigs were delivered from three farms and slaughtered over 2 weeks at either a dehiding or a scalding singeing slaughterhouse. Temperature and pH were measured at intervals from exsanguination until 6 hours post mortem. Ultimate pH, internal reflection, drip loss and colour (Minolta) were measured the day after slaughter. Colour (JPCS scale) was evaluated after freezing and thawing, and eating quality was estimated on unaged and aged (4 days at 4°C) m. longissimus dorsi (LD), using a trained taste panel. At the slaughter line the dehided carcasses had an almost constant and lower temperature compared to the scalded and singed carcasses. During chilling there is a shift in temperature curves between treatments, where the scalded carcasses had the lowest muscle temperature in LD and m. biceps femoris (BF) from 2hr post mortem and throughout the measuring period. In spite of the shift in temperature, the dehided carcasses had the highest pH in LD and BF from exsanguination and throughout the measuring period. The rate of pH fall in LD and BF was slowest in the dehided carcasses from exsanguination until 3 and 2hr respectively, post mortem. Dehided carcasses showed a 40% lower drip loss, a darker meat colour and a lower internal reflection in LD and BF compared to scalded and singed carcasses, thus indicating less protein denaturation in dehided carcasses. Scalding and singeing, however, lead to increased tenderness compared to dehiding, and this difference persisted even after ageing for 4 days at 4°C. The differences in toughness may be caused by increased proteolysis by released lysosomal cathepsins.     

Electrical stimulation of pigs-effect on pH fall, meat quality and Cathepsin B+L activity

This work was performed to evaluate the effect of electrical stimulation (ES) on pH fall and meat quality of LD and BF in Danish halothane free pigs stunned with CO(2). ES resulted in a significant drop in pH of 0.3 units in both LD and BF and 3 h lairage resulted in 0.1 units lower pH at 20 min post mortem. Lairage time did not affect and did not interact with the effect of ES on any of the measured meat quality parameters. ES did not affect the ultimate pH in LD, BF, SM and SC or internal reflection value in LD. However, ES caused higher internal reflection and drip loss in BF and increased the PSE frequency in LD (2 to 7%) and in BF (2 to 49%). The frequency of PSE areas in the centre of SM was 70% for ES pigs compared to 9% for control pigs. ES and ageing improved the tenderness and reduced the hardness in LD as well as shear force of unaged BF. The effect of ES on tenderness and hardness was approximately half the effect of ageing, but the effect of ES and ageing were additive. ES significantly increased the activities of cathepsin B+L in the myofibrillar fraction, but there were no differences in proteolytic activity in the other fractions. It is concluded that ES improves tenderness in LD and BF, but has a negative effect on the quality of BF and SM. Therefore ES is not an economically attractive alternative for improvement of tenderness in LD compared to ageing in Danish pigs. ?     

Effect of time between adrenaline injection and slaughter on the rate and extent of post-mortem metabolism in porcine skeletal muscle

The aim of this work was to study the effect of time between adrenaline injection and slaughter on the rate and extent of post-mortem metabolism in pig muscle. Five pigs were subcutaneously injected with adrenaline (0·3 mg/kg) or with a saline solution 4 h, 1 h or 15 min prior to slaughter. pH(1), pH(u) and FOP(u) were measured in Longissimus dorsi (LD) and Biceps femoris (BF) muscles. m.LD samples were taken 20 days before slaughter using biopsy sampling, immediately after bleeding and 45 min post mortem for biochemical analysis. m.LD glycolytic potential (very close to glycogen content) was decreased by the injection of adrenaline 4 h and 1 h prior to slaughter, when comparing values at rest (20 days before slaughter) and values determined immediately after bleeding. The depletion was greater fro the injection performed 4 h before slaughter. In this group pH(u) was higher foe adrenaline-injected pigs (5·69 versus 5·47 for pigs injected with saline solution) but the difference was not significant. Pigs injected with adrenaline 1 h prior to slaughter exhibited higher glucose, glucose-6-phosphate and lactate levels immediately after slaughter, lower pH(1) and higher FOP values in m.LD than control pigs. Since the differences in pH(1) were not explained by differences in the rate of build-up of lactate, it was hypothesized that pigs injected with adrenaline 1 h prior to slaughter had lower muscle pH at slaughter. It was concluded that the rate or the extent of post mortem metabolism in pig muscle may be affected independently, by manipulating the time between adrenaline injection and slaughter.     

Control of post mortem pH decrease in pig muscles: experimental design and testing of animal models

From a series of experiments aimed at manipulating and relating the resting levels of glycogen and creatine phosphate (CP) in the live muscle four models were selected to induce different rates and extents of pH decrease post mortem in pig muscle. Model A served as the control, animals being slaughtered under minimal stress, in model B animals were subjected to 10 min treadmill exercise at 3.8 km/h immediately prior to stunning, in model C, animals were given 0.2 mg adrenaline/kg live weight 16 h prior to slaughter, and in model D they were given 0.3 mg adrenaline/kg live weight 16 h before slaughter and subjected to 5 min of treadmill exercise immediately before stunning. After slaughter, the decline in pH and temperature post mortem was recorded in M. longissimus dorsi (LD), M. biceps femoris (BF), M. semimembranosus (SM) and M. psoas major (PM) from 1 min to 24 h after bleeding. Significant differences in ultimate pH and the time course of pH decrease were observed, both as an effect of model as well as type of muscle. No differences in ultimate pH between model A and model B were observed in any of the muscles. Ultimate pH in the C and the D models were significantly higher than in A and B. In the B model lower pH values were observed from 1 min to 6 h post bleeding compared to the other three models. No differences in rate of pH decrease were observed between the A and the B models in any of the muscles. Within the A model no differences in ultimate pH between muscles were seen, indicating that the frequently observed differences in ultimate pH are caused by environmental factors rather than by differences in physiological and morphological characteristics. The exercise bouts caused elevated temperatures during the first hour after bleeding (model B and D). The BF muscle in all the models displayed the fastest rate of pH decrease and SM the slowest; a slower rate of temperature decline occurred in the BF than in the SM.     

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 m²/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 m²/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.     

Influence of repeated restraint and isolation stress and electrolyte administration on carcass quality and muscle electrolyte content of sheep

Crossbred lambs were assigned, within weight blocks, to one of four treatments applied in a 2 × 2 factorial design (n = 6 per treatment). Treatment main effects included no stress (NS) or three consecutive days of restraint and isolation stress (RIS) and treatment with either water (W) or electrolytes (E). The experimental design resulted in four treatments, namely NS-lambs given W, NS-lambs given E, RIS-lambs given W, and RIS-lambs given E. Stress treatment consisted of moving each lamb from its home stanchion to a separate location and isolation from visual and tactile contact with other lambs for 6 hours daily for 3 days before slaughter. All lambs received a 320 ml oral drench of either W or E on each day after the stress treatment. Stress treatment reduced (P < 0·05) semitendinosus (ST) muscle glycogen by 4·8-fold. At 24 h post mortem, muscle pH for semimembranosus (SM), biceps femoris (BF) and infraspinatus (IF) was higher (P < 0·05) in RIS-lambs that in NS-lambs. Hunter L(?)a(?)b(?) values, measured on muscle cross-section, revealed a lighter (P < 0·05) BF; more (P < 0·05) red BF, ST, and longissimus dorsi (LD); and more (P < 0·05) yellow ST, SM, BF, and LD for NS-than for RIS-lambs. Muscle from RIS-lambs contained less (P < 0·05) potassium than that from NS-lambs. Restraint and isolation stress of lambs resulted in a reduction in muscle glycogen, but only slight increases in ultimate pH and minimal influences on muscle color. Administration of electrolytes had no effect on lamb carcass quality.     

Effects of halothane genotype and pre-slaughter treatment on pig meat quality. Part 1. Post mortem metabolism, meat quality indicators and sensory traits of m. Longissimus lumborum

Forty-eight castrated F₂ offspring of Piétrain and Large White pigs were allocated to a 3 × 2 factorial design in order to study the interactive effect of halothane genotype (NN, Nn and nn) and pre-slaughter treatment [referred to as ‘Experimental’ (EXP) and ‘Commercial-like’ (COL) conditions; the latter combining short transportation, mixing unfamiliar pigs and slaughtering shortly after transport] on muscle post mortem changes and meat quality. The pigs were slaughtered over 4 days. Pre-slaughter glycogen depletion in M. longissimus lumborum (LL) was greater in the nn pigs, compared with the two other genotypes. Lactate accumulation post mortem in LL muscle was greater and the pH value at 40 min post mortem was lower in nn compared with NN pigs. Nn pigs were close to nn pigs for lactate accumulation and showed intermediate pH values in the LL muscle. In the M. semimembranosus (SM), NN and Nn pigs showed the same rate of post mortem changes, as evidenced by similar glycogen, lactate, creatine phosphate and ATP levels, and pH values at 40 min post mortem. Pre-slaughter treatment did not affect the rate of post mortem changes in both muscles and no interactive effect with halothane genotype was found. The pigs slaughtered under the ‘COL’ conditions had a significantly higher ultimate pH in the LL and SM muscles than those slaughtered under the ‘EXP’ conditions. The LL muscle from nn pigs was paler (higher L*) than that of NN and Nn pigs. In SM muscle, Nn pigs showed a significantly higher L* value than NN pigs. Drip loss of the LL muscle was significantly higher in nn compared with NN pigs, the heterozygous pigs being intermediate. Sensory evaluation of the LL muscle showed that nn pigs had a lower colour intensity and colour homogeneity of raw meat than NN and Nn pigs. Tenderness was significantly lower in nn compared with NN pigs, the Nn pigs being intermediate. Pre-slaughter treatment significantly increased ultimate pH in both muscles (LL and SM) but did not affect significantly the rate of pH fall (pH₄₀). It did not affect any of the meat quality traits and no interactive effect with halothane genotype was found. These results confirmed the influence of the halothane gene on the kinetics of muscle post mortem changes and related meat quality traits. They also confirmed the intermediate position of heterozygous pigs in terms of meat quality.     

Influence of Pre-Slaughter Process on Pork Quality: An Overview

Handling practices prior to slaughter have significant influence in the stress level and animal welfare of pigs, and consequently, in the final meat quality. This paper reviews current knowledge about ante mortem factors (fasting period, farm handling, mixing, loading, unloading, transport, lairage conditions, and driving to the stunner) related to the live animal that influence pork quality with special emphasis on technological quality attributes. The development in slaughter technologies and their practical applications in pig slaughterhouses are described. In spite of genetic effects and slaughter techniques, poor pre-slaughter operations lead frequently to an increase of physiological and physical stress in pigs. Ante mortem factors, such as lairage time or moving pigs into the slaughter rooms, and inadequate design of slaughterhouse facilities have an important effect on pig stress, affecting meat quality after slaughter. Some recommendations to guarantee animal welfare and obtain the best meat quality are reviewed.     

The relationship between early post-mortem pH and the tenderisation of beef muscles

The rate of early post-mortem pH fall in bovine muscle was studied to determine its influence on the rate and extent of the tenderisation process. The pH of M. longissimus dorsi (LD) and M. semimembranosus (SM) muscles of Hereford cross Friesian heifers (n = 127) was taken up to 24 h post mortem. Twenty-four LD and 24 SM muscles were selected according to their rate of pH fall; slow (n = 8), intermediate (n = 8) and fast (n = 8) and were sampled at 2, 7 and 14 days post mortem for sensory, mechanical, physicochemical and biochemical analysis. Fast glycolysing LD muscles were rated more tender in sensory analysis and texture assessment whereas slow glycolysing muscles were considered significantly tougher (p < 0.001). Fast glycolysing LD had a significantly lower shear force (p < 0.001) at each stage of ageing. Slow glycolysing LD and SM had the highest shear force values. No significant difference was found in intramuscular fat or moisture content between the groups. Slow glycolysing LD muscles had shorter sarcomere lengths at 2 days post mortem. SDS-PAGE electrophoresis patterns showed increased proteolysis, such as the earlier appearance of the 30 kDa fragment, which is believed to be a good indicator of tenderness, in fast glycolysing muscle. These results suggest that the rate of post-mortem pH fall plays an important role in proteolysis and tenderisation.     

Low stress pre-slaughter handling: effect of lairage time on the meat quality of pork

The effect of lairage time on meat quality was investigated when crossbred pigs were subjected to low stress pre-slaughter handling, where pigs were treated in mixed groups of 15 from the farm to group CO(2) stunning, and where electric goads were not used at any time. Two experiments were carried out, one in spring (n=270) using very standardised conditions and one producer, and one in summer (n=630) using a representative randomly chosen sample of producers. In the first experiment three lairage times were used, less than 30 min (average 26 min), 90 min (average 83 min) and more than 150 min (average 170 min) and no showering. The pH and temperature were measured in the m. longissimus dorsi at various times post mortem, and colour (L(*), a(*), b(*)), internal reflectance and drip loss the day after slaughter. Sensory evaluation was carried out on 16 randomly chosen samples from the shortest and longest lairage time groups. Drip loss, pH(ultimate) and internal reflectance were also measured in the m. biceps femoris and pH(ultimate) and internal reflectance in the m. semimembranosus. Finally, pH(ultimate) was measured in the m. semispinalis capitis. In the second experiment only two lairage times were used, less than 30 min (average 17 min) and more than 130 min (average 150 min) and with intermittent showering and only a subset of the meat quality measurements were made. Lairage time had no effect on any of the meat quality parameters measured in experiment 1. In experiment 2 the shortest lairage time led to a higher temperature in the m. longissimus dorsi at 2 min post mortem, a higher drip loss in the m. biceps femoris and higher internal reflectance values in both muscles the day after slaughter. The differences were, however, very small and may have been an effect of showering.     

Manipulation of critical quality indicators and attributes in pork through vitamin E supplementation, muscle glycogen reducing finishing feeding and pre-slaughter stress

The combination of a muscle glycogen reducing diet or a standard diet (control group) with normal (80 mg/kg) and high vitamin E levels (500 mg/kg) and exercise immediately prior to slaughter was used on 56 pigs to investigate the influence on meat quality indicators (pH and temperature) and attributes (drip loss, colour and Warner–Bratzler shear force). The drip loss was reduced in M. longissimus dorsi, M. biceps femoris and M. semimembranosus in pigs given the muscle glycogen reducing diet compared with the control groups, the greatest effect was seen in exercised pigs. These results can be explained by an early post mortem reduction in glycometabolism in pigs fed muscle glycogen reducing diets rather than by an increase in ultimate pH. Noticeably, high dietary vitamin E level increased muscle glycogen stores by about 10% on the day prior to slaughter but not on the day of slaughter in both dietary groups compared with the low dietary vitamin E level, which in fact reduced rather than improved the water-holding capacity, especially in pigs fed the standard diet.     

Rest before slaughter ameliorates pre-slaughter stress-induced increased drip loss but not stress-induced increase in the toughness of pork

One factor affecting meat quality is pre-slaughter stress. We investigated the effects of exercise stress on drip loss and toughness in relation to resting times of 0, 1 or 3 h following exercise on a treadmill. This exercise stress was regarded as combined physical and physiological stress. Exercise stress increased the muscle temperature, reduced the creatine phosphate, ATP and glycogen content of pigs slaughtered immediately after stress exposure. These conditions lead to a reduced pH early post mortem and an increased drip loss, while only 1 h of rest after exercise stress normalised these effects. However, an overshooting effect was noted when pigs were rested for 1–3 h before slaughter, emphasising the importance of critical control of the resting period when studying exercise stress-induced effects on meat quality. Furthermore, meat from exercise stressed pigs, irrespective of resting, had increased toughness compared to controls, indicating that the toughness was not related to drip loss in meat from exercise stressed pigs.     

Effect of preslaughter handling on muscle glycogen level and selected meat quality traits in beef

The ante-mortem and post-mortem glycogen levels in bull muscle were studied to determine their influence on the ultimate pH, cooking loss and shear force. Forty-three bulls (13 Holstein, 12 crosses Holstein × Belgium blue, 9 Slovak Pied and 9 crosses Slovak Pinzgauer × Piemontese) were tied, housed and divided in control (A, n = 30) and stressed (B, n = 13) groups before slaughter. At the institute abattoir, the group B animals were mixed and kept overnight. In group A, bulls were slaughtered immediately after arrival at the abattoir. The following values of muscle were determined: (1) glycogen ante mortem from m. semitendinosus (ST) (biopsy technique, Biotech Nitra), (2) glycogen post mortem (1 hr, 3 hr, 48 hr) from longissimus dorsi muscle (LD), (3) ultimate pH, cooking loss and shear force 48 h post mortem. The results show that the glycogen concentrations ante mortem (ST) and 1 hr post mortem (LD) from unstressed animals were similar (p > 0.05). The ante-mortem and post-mortem (1 hr, 3 hr) muscle glycogen concentration were depleted (p < 0.01) in all stressed bulls. Differences between stressed and unstressed animals (p < 0.01) were found in ultimate pH, cooking loss and in shear force (p < 0.05). Significant correlations (p < 0.01) between ante-mortem (ST) and postmortem (LD, 1 hr, 3 hr) muscle glycogen and ultimate pH and cooking loss supported the possibility of using an efficient biopsy technique in combination with a simple method of glycogen estimation (iodide method) to predict metabolic exhaustion (glycogen depletion) and/or dark cutting condition of bulls.     

The interaction between calpastatin and RYR1 genes for some pork quality traits

This study was performed in order to investigate a relationship between polymorphism's of calapastatin gene (CAST) identified with HinfI, MspI and RsaI restriction endonucleases in pigs and meat quality characteristics and also interactions between CAST and RYR1 genes. Investigations were carried out on group of 89 fatteners being crosses of (Polish Large White×Polish Landrace)×(Hampshire×Pietrain). Some meat quality characteristics, glycolytic potential of LL muscle, yield of curing meat in cooking, the yield of loin in curing and smoking processes were determined. Statistically significant influence of RYR1 genotype (CC and CT) on investigated traits wasn't affirmed. A significant effect of CAST genotype on the value of several meat quality traits was noticed. Interactions between RYR1 and CAST genes were statistically significant for pH(45) value (CAST/RsaI×RYR1) and for drip loss (CAST/HinfI×RYR1). Obtained results showed that glycogen level in LL muscle in 45 min post mortem depends on CAST/MspI and CAST/RsaI genotypes while glycolytic potential depends on CAST/RsaI genotype. Genotyp AA at CAST/RsaI locus and AA genotype at CAST/HinfI locus stopped disclose of effect of RYR1 gene mutation for pH(45) in LD muscle and for drip loss respectively. Animals heterozygous in RYR1 locus (CT) being BB homozygotes at CAST/RsaI locus produced meat with highest pH(45) value (6,4) and dark meat colour. For technological properties of meat most interesting are double heterozygotes at the loci RYR1 and CAST/HinfI with significantly lowest (P?0.01) drip loss (4,04%).     

Rest before slaughter ameliorates pre-slaughter stress-induced increased drip loss but not stress-induced increase in the toughness of pork

One factor affecting meat quality is pre-slaughter stress. We investigated the effects of exercise stress on drip loss and toughness in relation to resting times of 0, 1 or 3 h following exercise on a treadmill. This exercise stress was regarded as combined physical and physiological stress. Exercise stress increased the muscle temperature, reduced the creatine phosphate, ATP and glycogen content of pigs slaughtered immediately after stress exposure. These conditions lead to a reduced pH early post mortem and an increased drip loss, while only 1 h of rest after exercise stress normalised these effects. However, an overshooting effect was noted when pigs were rested for 1–3 h before slaughter, emphasising the importance of critical control of the resting period when studying exercise stress-induced effects on meat quality. Furthermore, meat from exercise stressed pigs, irrespective of resting, had increased toughness compared to controls, indicating that the toughness was not related to drip loss in meat from exercise stressed pigs.     

Use of infrared ocular thermography to assess physiological conditions of pigs prior to slaughter and predict pork quality variation

Infrared thermography (IRT) body temperature readings were taken in the ocular region of 258 pigs immediately before slaughter. Levels of lactate were measured in blood taken in the restrainer. Meat quality was assessed in the longissimus dorsi (LD), semimembranosus (SM), and adductor muscles. Ocular IRT (IROT) temperature was correlated with blood lactate levels (r = 0.20; P = 0.001), with pH taken 1 hour postmortem (pH1: r = − 0.18; P = 0.03) and drip loss (r = 0.20; P = 0.02) in the LD muscle, and with pH1 in the SM muscle (r = − 0.20; P = 0.02). Potentially, IROT may be a useful tool to assess the physiological conditions of pigs at slaughter and predict the variation of important meat quality traits. However, the magnitude of the correlations is rather low, so a further development of image capture technique and further studies under more variable preslaughter conditions ensuring a larger pork quality variation are needed.     

Perspective of NIRS measurements early post mortem for prediction of pork quality

The potential of near-infrared spectroscopy (NIRS) measurements early post mortem was investigated to predict ultimate drip loss, colour, tenderness and intra-muscular fat of pork. Three locations (M. longissimus thoracis, M. longissimus lumborum and M. semimembranosus) in 102 pig carcasses were tested at the end of the slaughter line. A priori variation in pork quality was introduced using an experimental design covering: genotype, lairage time, pre-slaughter handling and day of slaughter. At 1 h post mortem a diode array VIS/NIR instrument (Zeiss MCS 511/522, 380-1700 nm) equipped with a surface fibre optic probe was used and at 1 day post mortem ultimate pH, drip loss, colour and shear force was measured on similar locations. Results indicated that it was possible to predict intra-muscular fat content (correlation (R(2) of 0.35 with multiple linear regression), standard error of prediction (SEP)=3.6 g/kg), but the configuration has to be refined for on-line application (bigger aperture). For drip loss no correlation was achieved with the PLS method. Even extremes (low drip loss (<2.5%) or high drip loss (>4.5%)) in drip loss were not discriminated. Predicting drip loss with NIRS early post mortem is not successful, although NIRS in the slaughter line has potential as a fast predictor of intra-muscular fat. Possibilities for using the NIRS technique to get to know more about muscle metabolism and post mortem changes are promising.     

Explaining and predicting differences in meat quality through stress reactions at slaughter: The case of Large White and Duroc pigs

Large White and Duroc pigs (n=42) were group-reared on straw. Durocs were more active in the home pens and had higher basal urinary cortisol levels. During tests, Durocs touched more often an unfamiliar human, but not an unfamiliar object, than Large Whites. Pigs were experimentally (low stress) or industrially (high stress) slaughtered. Meat (Longissimus lumborum (LL), Biceps femoris (BF), Adductor femoris (AF) and Semimembranosus (SM)) was darker, more yellow, had higher ultimate pH and better water holding capacity after high, compared to low-stress slaughter. Large White meat contained less pre-slaughter glycogen, was redder and lost more drip. Slaughter conditions influenced ultimate pH of Large White more than of Duroc meat. Large Whites, and to a lesser extent Durocs, touching the human less often during the test, had faster early post-mortem LL and BF muscle metabolism. Pigs exploring the unfamiliar object more often were more aggressive during pre-slaughter mixing and had higher AF and SM ultimate pH.     

Effects of pithing on pH, creatine phosphate and ATP-related compounds of beef Psoas major and Longissimus dorsi muscles

The effects of pithing at slaughter on meat quality were studied in M. longissimus dorsi (LD muscle) and M. psoas major (PM muscle) from steers. Ten steers, half of them pithed and the others not pithed at slaughter, were used for determining pH values and concentrations of creatine phosphate (CP), adenosine triphosphate (ATP) and its breakdown products in the muscles at 2·0 h post mortem. CP was not detected in any PM muscles from pithed steers and no significant differences were observed between pithed and non-pithed steers on the mean values of pH and any compounds, but significant differences were observed in the variance of pH value, ATP, (inosine monophosphate IMP) and inosine levels in PM muscles and of (adenosine diphosphate ADP) and IMP levels in LD muscles. When two steers with excitable temperament were excluded from the pithed group significant differences of variance between the treatments were observed only in PM muscles. The pithing procedure thus affects the levels of pH and of some of the ATP-related compounds in the PM but not in LD muscles.