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Simple Summary: Positive and negative pressure ventilation systems are widely used in poultry farming to control the internal environment of poultry houses, especially in tropical regions, in which hot and humid climates can pose challenges to the thermal regulation of animals. Knowing that thermal stress impacts the quality of animal meat, this study aimed to evaluate the thermal performance and quality of poultry meat in these two types of shed. The main results found here were that the negative pressure system presents lower temperatures and air enthalpy, and the animals reared in this system have better quality meat. We recommend the negative ventilation system for broiler producers in tropical regions due to its ability to provide better thermal indicators and chicken meat quality. This study aimed to evaluate the thermal performance and meat quality in broilers reared in positive pressure tunnel ventilation (PP) and negative pressure tunnel ventilation (NP) in production houses. 320 Cobb broilers (40 broilers per house) were used. Pectoralis major muscles from 40 broilers (10 broilers per house) were randomly selected and analysed for L* (lightness), a* (redness), b* (yellowness), pH, drip loss (DL), cooking loss (CL) and shear force (SF). Air temperature and humidity of the transportation and slaughterhouse waiting room were recorded in the last week of rearing. Subsequently, the enthalpy comfort index (ECI) was calculated. Air temperature and ECI were higher (p < 0.05) in positive pressure sheds, whereas relative humidity was higher (p < 0.001) in negative pressure sheds. There was no statistically significant difference between the enthalpy comfort index during transport and lairage (p > 0.005). Meat quality defects (high L*, DL, CL, SF) were found in PP and NP. It was observed that b* was higher in PP, although pH and CL were higher in NP. Differences in pH, b* and CL indicate that broilers from PP had a higher level of heat stress. In conclusion, differences in pH, b*value and cooking loss in breast broilers indicate that birds in PP had a higher level of heat stress. Additional studies investigating pre-slaughter handling methods to minimise injuries and heat stress are recommended in order to improve animal welfare and meat quality. [ABSTRACT FROM AUTHOR]

The high PSE incidence of pork reduced pork quality and restricted the down-stream processing of pork. Lots of scholars have studied the factors affecting the development of PSE pork recently, especially supplementary feeding before slaughter has become a research hotspot to reduce the incidence of PSE pork. However, there is a lack of systematic and in-depth review of the latest research results. This paper systematically summarizes the genetic and environmental factors affecting the development of PSE pork and the control measures. It mainly summarizes the effects and mechanism of the supplementation of vitamins, amino acids, electrolyte mineral elements, and natural compounds during fasting on PSE pork. The underlying mechanism of nutritional additives could reduce PSE incidence mainly includes increasing the content of superoxide dismutase and glutathione in serum, removing oxidizing free radicals and interrupting lipid peroxidation, delaying the decline of muscle pH after slaughter, improving the water holding capability of pork, and acting as the main source of energy material supply under stress. In addition, 1~3 h fasting time, −10~30 ℃ transport temperature, 6 min scalding time at 60 ℃, and the use of carbon dioxide stunning and two-stage chilling can also effectively reduce the occurrence of PSE meat.

Copyright of MESO is the property of Zadruzna Stampa D.D. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aimed to evaluate the thermal performance and meat quality in broilers reared in positive pressure tunnel ventilation (PP) and negative pressure tunnel ventilation (NP) in production houses. 320 Cobb broilers (40 broilers per house) were used. Pectoralis major muscles from 40 broilers (10 broilers per house) were randomly selected and analysed for L* (lightness), a* (redness), b* (yellowness), pH, drip loss (DL), cooking loss (CL) and shear force (SF). Air temperature and humidity of the transportation and slaughterhouse waiting room were recorded in the last week of rearing. Subsequently, the enthalpy comfort index (ECI) was calculated. Air temperature and ECI were higher (p < 0.05) in positive pressure sheds, whereas relative humidity was higher (p < 0.001) in negative pressure sheds. There was no statistically significant difference between the enthalpy comfort index during transport and lairage (p > 0.005). Meat quality defects (high L*, DL, CL, SF) were found in PP and NP. It was observed that b* was higher in PP, although pH and CL were higher in NP. Differences in pH, b* and CL indicate that broilers from PP had a higher level of heat stress. In conclusion, differences in pH, b*value and cooking loss in breast broilers indicate that birds in PP had a higher level of heat stress. Additional studies investigating pre-slaughter handling methods to minimise injuries and heat stress are recommended in order to improve animal welfare and meat quality.

Copyright of Kocatepe Veterinary Journal / Kocatepe Veteriner Dergisi is the property of Afyon Kocatepe University, Faculty of Veterinary Medicine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

PSE meat has poor color, rough taste and poor meat quality, which directly affects the sales quality of meat and causes economic losses to livestock slaughter and meat processing. The paper reviews the mechanism of PSE meat occurrence, and discusses the role of zinc in regulating the anti-oxidative stress system of animal body through auxiliary anti-oxidation and the role of trace element zinc in preventing PSE meat production, to provide reference for effective prevention and reduction of PSE meat production. [ABSTRACT FROM AUTHOR]

In this paper, the protein changes during aging and the differences in the myofibrillar protein fraction at 1 h postmortem of pale, soft and exudative (PSE), and red, firm and non-exudative (RFN) pork longissimus thoracis (LT) were comparatively studied. The PSE and RFN groups were screened out based on the differences in their pH and lightness (L*) at 1 h, and their purge loss at 24 h postmortem. Based on the measured MFI, desmin degradation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, PSE meat presented more significant changes in the myofibrillar protein fraction compared to RFN meat during postmortem aging. Through liquid chromatograph-mass spectrometer/mass spectrometer (LC-MS/MS) analysis, a total of 172 differential proteins were identified, among which 151 were up-regulated and 21 were down-regulated in the PSE group. The differential proteins were muscle contraction, motor proteins, microfilaments, microtubules, glycolysis, glycogen metabolism, energy metabolism, molecular chaperones, transport, and enzyme proteins. The AMP activated protein kinase (AMPK) signaling pathway, HIF-1 signaling pathway, calcium signaling pathway, and PI3K-Akt signaling pathway were identified as the significant pathways related to meat quality. This study suggested that the different changes of the myofibrillar protein fraction were involved in the biochemical metabolism in postmortem muscle, which may contribute to the molecular understanding of PSE meat formation.

The aim of this study was to determine the effect of gender, stocking density in the transport vehicle, lairage time and season on the incidence of skin lesions on pig carcasses and PSE and DFD meat. Skin lesions on carcasses (480, in total) were assessed according to the Welfare Quality® protocol (2009). The pH and temperature measurements were performed 45 minutes after slaughter. The group of carcasses with skin lesions score 2 had significantly higher incidence of PSE and DFD meat compared to the groups of carcasses with skin lesions score 0 and 1. With regard to gender, there were no differences in meat quality parameters, as well as for the incidence of skin lesions and PSE and DFD meat. The results showed that a space allowance lower than 0.3 m2/100 kg and higher than 0.5 m2/100 kg pig had a detrimental effect to animal welfare and meat quality. Lairage time affected meat quality parameters, incidence of skin lesions score and PSE and DFD meat, where after long lairaging (> 17 h) mean pH45 and t45 values became significantly higher, as well as the incidence of skin lesions and DFD meat. After short lairaging (< 1 h) mean pH45 value became significantly lower, while mean t45 value and the incidence of PSE meat became significantly higher. A significantly higher number of skin lesions on the carcass were observed in winter compared to all other seasons. High temperatures during summer and low temperatures during winter had a negative influence on meat quality parameters and incidence of PSE and DFD meat.

ABSTRACT The objective of this study was to determine the incidence of Pale, Soft, Exudative (PSE) meat and to characterize the Dark, Fim, Dry (DFD) meat as well as the Dead on Arrival (DOA) index in a commercial turkey slaughterhouse in southern Brazil during the summer and winter seasons. The journeys (n=64) were over a distance of 36 ± 20 km and took approximately 95 ± 20 min. Color (L*) and pH distribution of turkey breast meat (n=5,352) were evaluated from different farms (n=64) during the 2015-2016 years. The pH, water-holding capacity, color (L*, a*, b*) were used to establish cutoff values for DFD meat (L* < 44.0 and pH > 5.90) and presented correlation among them. The L* value was the highest during the summer (P

This study evaluated moisture content of broiler breast PSE meat by thermal gravimetric analysis and strong cation elements by inductively coupled plasma optical emission spectrometry. The weight changes were monitored within the temperature interval 9-750 °C and the most severe changes were observed at 9-160 °C (1A). This remarkable transition was attributed to water loss of about 64.74% in normal samples while PSE samples lost about 61.16%. There was, therefore, approximately 4.0% lower moisture in PSE meat samples in relation to normal meat. The analysis of cation elements showed significant differences (p < 0.05), with normal samples having 13.0% higher ∑[Ca2+] + [Mg2+] + [Na+]+[K+] than PSE meat samples while [Ca2+] in PSE meat was 10.81% higher than in the normal counterparts. We provided further evidence of the role of Ca2+ excess within the muscle sarcomere during the onset of PSE meat. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of pre-slaughter handling on the occurrence of PSE (Pale, Soft, and Exudative) meat in swine slaughtered at a commercial slaughterhouse located in the metropolitan region of Dourados, Mato Grosso do Sul, Brazil. Based on the database (n=1,832 carcasses), it was possible to apply the integrated multivariate analysis for the purpose of identifying, among the selected variables, those of greatest relevance to this study. Results of the Principal Component Analysis showed that the first five components explained 89.28% of total variance. In the Factor Analysis, the first factor represented the thermal stress and fatiguing conditions for swine during pre-slaughter handling. In general, this study indicated the importance of the pre-slaughter handling stages, evidencing those of greatest stress and threat to animal welfare and pork quality, which are transport time, resting period, lairage time before unloading, unloading time, and ambience.

The aim of this study was to determine the association of lung lesions with carcass and meat quality traits in slaughter pigs and to describe the main morphological features associated with lung lesions. Macroscopic lesions on the lungs were detected in 67.09% of a total of 79 pigs examined. Histopathological examination revealed that acute and chronic interstitial pneumonia represented the commonest changes, detected in 26.67% and 33.33% of the cases, respectively. Bronchopneumonia was found in 33.33% of the cases. By immunohistochemical examination, 26.67% of the lungs showed the presence of severe peribronchiolar and perialveolar infiltration composed predominantly of CD3+ T lymphocytes, which finding may be indicative of viral pneumonia. Regarding the production traits, it was confirmed that pigs with severe lung lesions had the lowest liveweight, hot carcass weight and meatiness, the highest pH value 45 min after slaughtering (pH45) and the highest incidence of dark, firm, dry (DFD) and pale, soft, exudative (PSE) meat. The presence of lung lesions significantly downgraded carcass value and caused a significant deterioration in pork quality. [ABSTRACT FROM AUTHOR]

A fast, sensitive and effective method based on the blood biochemical parameters for the detection of PSE meat was developed in this study. A total of 200 pigs were slaughtered in the same slaughterhouse. Meat quality was evaluated by measuring pH, electrical conductivity and color at 45 min, 2 h and 24 h after slaughtering in M. longissimus thoracis et lumborum (LD). Blood biochemical parameters were determined in blood samples collected during carcass bleeding. Principal component analysis (PCA) biplot showed that high levels of exsanguination Creatine Kinase, Lactate Dehydrogenase, Aspertate aminotransferase, blood glucose and lactate were associated with the PSE meat, and the five biochemical parameters were found to be good indicators of PSE meat Discriminant function analysis (DFA) was able to clearly identify PSE meat using the five biochemical parameters as input data, and the class model is an effective diagnostic tool in pigs which can be used to detect the PSE meat and reduce economic loss for the company. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the effect of blue light diffuser on the broiler stress control by measuring the occurrence of PSE meat just before slaughtering. Birds were divided into the following two groups before slaughter at the point of being hung on shackles: broiler group under low intensity blue light ambience (475, 17-20 lx) and control group under white light (550-650nm, 321-332 lx). Birds' stressful conditions were measured by the occurrence of PSE meat. Breast fillets were classified as PSE meat based on pH ( 53.0). The fillet samples in the control group had the following characteristics: pHu=5.77, L* = 54.26 and b*= 6.27. The fillet samples from birds under blue light ambience had the following characteristics: pHu=5.81, L* = 52.86 and b* = 5.22 (p < 0.05). These results revealed that the treatment of blue light ambience just before slaughtering contributed to the alleviation of ante mortem stress of the birds, which was observed by a 14% decrease in the occurrence of PSE meat. Exposure to blue light just before slaughtering was shown to have potential to be used in modern slaughterhouses to offer a comfortable atmosphere, thereby maintaining breast meat quality.

A total of 192 broiler chicks were used to evaluate the influence of dietary α-lipoic acid (ALA) on growth performance, carcass characteristics and meat quality of broiler chickens with the purpose of developing a strategy to prevent the occurrence of pale, soft, and exudative (PSE) meat and to improve the meat quality of broilers. At 22 d of age, birds were allocated to 4 ALA treatments (0, 400, 800, and 1200 ppm). The results showed that dietary ALA significantly decreased average feed intake (AFI), average daily gain (ADG), final live body weight (BW) and carcass weight (p

The objective of this work was to evaluate the effects of alkaline solution marinades on the characteristics of pork subjected to post-mortem pH decrease in pig muscle. The pH of carcasses was measured in a commercial slaughterhouse (n = 526), 45 min after slaughtering (pH45) and, then, the carcasses were divided into the groups with pH455.7. Ten samples of the longissimus dorsi muscles of each group were collected and distributed in an entirely randomized design, in a 2x4 factorial arrangement, with two conditions (pH455.7), and four marinade solutions: TC, no marinade; TM1, sodium bicarbonate and sodium chloride; TM2, sodium tripolyphosphate and sodium chloride; TM3, sodium bicarbonate, sodium tripolyphosphate and sodium chloride. There was no interaction between pH45 of the meat and the marinade treatments. Meat with pH45O objetivo deste trabalho foi avaliar os efeitos de marinadas com soluções alcalinas sobre características da carne de porco submetida a quedas do pH post-mortem, em músculo de porco. O pH das carcaças foi medido em abatedouro comercial (n = 526), aos 45 min pós-abate (pH45) e, em seguida, as carcaças foram divididas em grupos com pH455,7. Dez amostras do músculo longissimus dorsi de cada grupo foram coletadas e distribuídas em delineamento inteiramente casualizado, em arranjo fatorial 2x4, com duas condições (pH455,7) e quatro soluções de marinação: TC, controle sem marinação; TM1, bicarbonato de sódio e cloreto de sódio; TM2, tripolifosfato de sódio e cloreto de sódio; TM3, bicarbonato de sódio, tripolifosfato de sódio e cloreto de sódio. Não houve interação entre o pH45 da carne e os tratamentos marinados. As carnes com pH45

The aim of this work was to study the influence of lipid oxidation on broiler breast meat (Pectoralis major m) color abnormalities. There were 27.0 % more lipid oxidation in PSE in relation to normal meat and 41.0 % more in relation to DFD-like meat (pA influência da oxidação lipídica no surgimento das anormalidades das cores do filé do peito de frango (Pectoralis major) foi avaliado. A oxidação lipídica foi 27 % maior em carnes PSE em relação ao normal e 41,0% em relação ao análogo DFD (p< 0.05). O perfil dos ácidos graxos foi também significantemente diferente desde que a fração do ácido araquidônico (AA) aumentou 38,6% e 70,5% em carnes PSE em comparação às carnes normais e análogas ao DFD, respectivamente. A razão PUFA/SFA se alterou nos três tipos de carne, 0,736, 0,713 e 0,694 para carnes PSE, normal e análogo ao DFD, respectivamente, refletindo a maior produção dos ácidos graxos polinsaturados em amostras PSE. Esses resultados corroboram os nossos anteriores, indicando que a atividade da enzima fosfolipase A2 tem um papel relevante no desenvolvimento da síndrome do PSE em uma cascata de reações bioquímicas promovendo a formação dos compostos radicais livres do AA que finalmente compromete os sistemas das membranas celulares do músculo.

The aim of this work was to evaluate the influence of time of broiler chicken transportation and lairage prior to slaughtering on the occurrence of PSE (Pale, Soft, Exudative) meat and Death On Arrival (DOA) under non-commercial conditions in the Brazilian summer. Male birds (n=250) from a commercial line were subjected to different periods of journey (30, 90, and 180 min) and lairage (0, 90, and 180 min) before slaughtering. The occurrence of PSE was higher in broilers subjected to shorter journeys and lairage periods, whereas DOA was more pronounced upon longer periods of transport and lairage. The DOA occurrence percentage was much higher in comparison to commercially available figures, confirming that broiler chickens are very sensitive to both transport and lairage maneuvers.O objetivo desse trabalho foi avaliar a influência do tempo de transporte e período de descanso antes do abate dos frangos na ocorrência das carnes PSE (Pale, Soft, Exudative: Pálido, Amolecido e Exsudativo) e DOA (Dead On Arrival: Morte Na Chegada) nas condições não comerciais durante o verão brasileiro. Frangos machos (n=250) de uma linhagem comercial foram submetidos a diferentes periodos de jornada (30, 90 e 180 min) e descanso (0, 90 e 180 min) antes do abate. A ocorrência do PSE foi maior em frangos submetidos tanto em tempos para as viagens curtas como para o de descanso enquanto que DOA foi mais pronunciada em condições de jornadas longas e maior periodo de descanso. A porcentagem da ocorrência do DOA foi maior ao se comparar com os resultados obtidas por empresas comerciais confirmando que os frangos são sensiveis às condições das viagens e de descanso a que são submetidos.

The connections between the redox imbalance in post-mortem muscle, early protein oxidation and the onset of pale, soft and exudative (PSE) condition in chicken breast are studied. PSE was induced by incubation of post-mortem chicken carcasses at 37 °C for 200 min. PSE-induced muscle consistently had faster pH decline and lower pH at 200 min (5.84 vs. 6.59) and 24 h (5.69 vs. 5.96), higher L ∗ (54.4 vs. 57.3), and lower texture and water holding capacity (WHC) than normal meat. The activities of catalase, glutathione peroxidase and superoxide dismutase were significantly lower in PSE-induced samples than in the normal counterparts. PSE was more susceptible to proteolysis and protein oxidation than normal meat during succeeding chilled storage with more intense tryptophan and thiols depletion, higher protein carbonylation and more intense formation of protein cross-links. We provide plausible explanations to support the role of protein oxidation in the impaired quality PSE chicken. [ABSTRACT FROM AUTHOR]

Este trabalho foi realizado com o objetivo de avaliar o efeito da adição de ractopamina na ração sobre a qualidade da carne de suínos dos genótipos halotano homozigoto dominante (HalNN) e heterozigoto (HalNn). Durante o experimento (21 dias), 24 suínos machos castrados e 12 fêmeas (metade de cada genótipo) com peso médio inicial de 72,6 kg de PV foram avaliados segundo delineamento experimental em blocos casualizados, em arranjo fatorial 2 x 2 x 2 (dois genótipos halotano; duas rações: controle e com adição de 10 ppm de ractopamina; e dois sexos: machos castrados e fêmeas). A análise do DNA genômico foi realizada por intermédio das técnicas de PCR-RLPC. A avaliação da qualidade da carne foi realizada no músculo Longissimus dorsi e o pH da carne foi medido 45 minutos (pH inicial) e 24 horas após o abate (pH final). Avaliaram-se a perda de água por gotejamento durante o degelo e a cocção, a cor da carne, o grau de marmoreio e a maciez objetiva. Não houve interação genótipo ´ ractopamina para as características de qualidade da carne avaliadas. Nenhum animal do genótipo homozigoto dominante apresentou carne PSE (textura mole, cor pálida e com pouca água), ao passo que os suínos do genótipo heterozigoto apresentaram carne com 33,3% de PSE. O uso de 10 ppm de ractopamina na ração não afetou os parâmetros de qualidade da carne. Os animais do genótipo HalNn apresentaram carne com qualidade inferior à dos suínos HalNN. O pH final foi menor e a incidência de carne PSE foi maior nos suínos machos castrados que nas fêmeas.The effect of adding dietary ractopamine on meat quality of dominant homozygote (HalNN) and heterozygote (HalNn) halothane animal genotypes was evaluated in this trial. During the experiment (21days), it was used 24 barrows and 12 gilts (half of each halothane genotype) averaging 72.6 kg initial BW. The experiment was analyzed as a randomized block with a 2 x 2 x 2 factorial arrangement (two halothane genotypes, two diets: control and with 10 ppm of ractopamine and two categories: barrows and gilts). The genomic DNA evaluation was performed by PCR-RLPC. Longissimus dorsi muscle was used for measurement of initial pH (pH45), final pH (pH24) and drip, chilling and cooking losses, meat color, marbleness, and objective softness. No effect of genotype ´ ractopamine interaction on meat characteristic was noticed. Meat of HalNN animals did no show thawing loss and paler (PSE) while that of HalNn had about 33.3% of PSE. Ractopamine did not affect meat quality parameters. Meat of HalNn animals had lower quality than those of HalNN pigs. Meat from barrows presented lower final pH and higher PSE incidence than gilts.

The aim of this study was to determine the effects of gender, slaughter weight, stocking density, lairage time and season on carcass and meat quality parameters in a low-input production system. The study was conducted on 400 slaughter pigs (200 barrows and 200 gilts) with live weight of 115.0 ± 4.70 kg. Barrows had higher slaughter and carcass weights, fat thickness and lower meatiness. Heavier pigs had higher hot and cold carcass weights, fat thickness, lower meatiness, and higher incidences of pale, soft and exudative (PSE) and dark, firm and dry (DFD) meat. Low stocking density during transportation increased skin lesion score, pH45 value and the incidence of DFD meat; while high stocking density decreased pH45 value and increased T45 value and the incidence of PSE meat. Long lairaging reduced slaughter weight, carcass weight, dressing percentage and backfat thickness and increased skin lesion score. After overnight lairaging, pH45 value and the incidence of DFD meat became higher. After short lairaging, the pH45 value was lower, while the incidence of PSE meat increased. Pigs slaughtered in winter had the highest slaughter weight, backfat thickness, pH45 value and incidence of DFD, and the lowest meatiness. Pigs slaughtered in summer had the lowest slaughter and carcass weights and pH45 value, and the highest incidence of PSE meat. In conclusion, gender influenced carcass quality, slaughter weight and lairage time, and season affected carcass and meat quality, while stocking density had an impact on meat quality. [ABSTRACT FROM AUTHOR]

BACKGROUND Pale, soft and exudative ( PSE) meat is a quality problem that causes a large economic loss to the pork industry. In the present work, near infrared ( NIR) quantification and identification methods were used to investigate the feasibility of differentiating potential PSE meat from normal meat. RESULTS NIR quantification models were developed to estimate meat pH and colour attributes ( L*, a*, b*). Promising results were reported for prediction of muscle pH ( R2CV = 70.10%, RPDCV = 1.83) and L* ( R2CV = 77.18%, RPDCV = 1.91), but it is still hard to promote to practical application at this level. The Factorisation Method applied to NIR spectra could differentiate potential PSE meat from normal meat at 3 h post-mortem. Correlation analysis showed significant relationship between NIR data and LF-NMR T2 components that were indicative of water distribution and mobility in muscle. PSE meat had unconventionally faster energy metabolism than normal meat, which caused greater water mobility. CONCLUSION NIR spectra coupled with the Factorisation Method could be a promising technology to identify potential PSE meat. The difference in the intensity of H2O absorbance peaks between PSE and normal meat might be the basis of this identification method. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study investigates the relationship between sound levels, pre-slaughter handling during loading and pork quality. Pre-slaughter variables were investigated from loading till slaughter. A total of 3213 pigs were measured 30 min post-mortem for pH 30LT ( M. Longissimus thoracis ). First, a sound level model for the risk to develop PSE meat was established. The difference in maximum and mean sound level during loading, mean sound level during lairage and mean sound level prior to stunning remained significant within the model. This indicated that sound levels during loading had a significant added value to former sound models. Moreover, this study completed the global classification checklist (Vermeulen et al., 2015a) by developing a linear mixed model for pH 30LT and PSE prevalence, with the difference in maximum and mean sound level measured during loading, the feed withdrawal period and the difference in temperature during loading and lairage. Hence, this study provided new insights over previous research where loading procedures were not included. [ABSTRACT FROM AUTHOR]

Eight pale, soft and exudative (PSE) and eight reddish-pink, firm and non-exudative (RFN) porcine longissimus muscle samples were selected based on pH and L* at 1 h postmortem (PM), and drip loss at 24 h PM, and used to evaluate the cellular calcium and apoptosis status. We found that SERCA1 was decreased, while IP3R was decreased in PSE meat ( P < 0.05), indicative of the overloaded sarcoplasmic calcium status. In PSE meat, the pro-apoptotic factor BAX was increased while the anti-apoptotic factor Bcl-2 was decreased ( P < 0.05). The significantly increased activity of caspase 3 and the expression of its cleavage fragment suggested higher apoptotic potential in PSE meat compared with RFN meat ( P < 0.05). Moreover, the significantly higher expression level of cytochrome C ( P < 0.05) suggests the important role of mitochondria during apoptosis appearance in PSE meat. Taken together, our data inferred that the calcium channel disorder present in PSE meat was associated with the increased apoptotic potential. [ABSTRACT FROM AUTHOR]

La condición PSE (pálida, suave y exudativa) altera el color, la textura y el sabor de la carne, acidificándola y ocasionándole baja retención de agua, menor valor nutricional y rechazo por el consumidor. Para determinar la presencia de la característica PSE se hace medición de pH a 45 minutos (pH45) y a 24 horas post-mortem (pH24), en 520 canales de cerdo. Los valores medios de pH45 indican que el 33.65% de las canales son PSE, el 47.12% es carne normal y el 19.23% se clasifica como DFD (oscura, firme y seca). El pH24 indica aumento de PSE llegando al 68% de las canales, mientras que los porcentajes de carne normal (31.23%) y DFD (0.77%) disminuyen. Al comparar el cambio de los estados de la carne entre 45 minutos y 24 horas, el 62.44% de la carne normal pasa a ser PSE, el 87% de carne DFD pasa a ser PSE, y el 94.85% de carne PSE continua igual. Las canales presentan alta incidencia de la condición PSE tanto a 45 minutos, como a 24 horas, indicando problemas antes y después del sacrificio. Existe diferencia altamente significativa (P < 0.01) para los tres estados de la carne evaluados entre las mediciones de pH45 y pH24.The PSE (pale, soft and exudative) meat condition alters the color, the texture and the flavor of pork, increasing its acidity and occasioning low water retention, low nutritional level and rejection by the consumer. To determine the presence of the PSE characteristic, the pork carcasses are evaluated by pH measurements at 45 minutes (pH45) and 24 hours (pH24 after the slaughter of the pigs. The mean pH45 values indicate that 33.65% of the carcasses present the PSE condition, 47.12% are Normal and 19.23 % can be described as DFD (dark, firm and dry). The pH24 values indicate an increase in the PSE carcasses up to 68% while the normal and DFD ones decrease to 31.23 % and 0.77%, respectively. Comparing the change of the meat characteristics from 45 min to 24 hours, after the pig slaughter , it is observed that 62.44% of the normal meat and 87% of DFD one become PSE meat and 94.85% of the initial PSE one does not suffer any transformation. The pork carcasses present high incidence of the PSE characteristics at 45 minutes as well as 24 hours, indicating that there is problems before and after the slaughter of the pigs. High statistically significant difference (P < 0.01) is found for the three meat conditions evaluated at pH45 and pH24.

• Myofibrillar protein of S-nitrosylation in pork longissimus thoracis was identified. • Differential SNO-modified proteins between PSE and RFN meat were analyzed. • S-nitrocysteines of myosin and actin were differentially detected in two meat groups. • Sarcomeric protein S-nitrosylation could be an alternative pathway of NO affecting meat quality. In this paper, the S-nitrosylated myofibrillar protein in pork was comparatively analyzed between pale, soft, and exudative (PSE) and red, firm, and non-exudative (RFN) meat. The S-nitrosothiol and immunoblot of S-nitrosylated protein indicated that the overall protein S-nitrosylation level in PSE pork was higher than that in RFN pork. Proteomics showed that 114 SNO-modified cysteines corresponding to 65 proteins were over-expressed in PSE samples while 74 nitrosylated cysteines of 20 proteins were over-expressed in RFN samples. Differential proteins including myosin, actin, actinin, nebulin, titin, troponin-I, and filamin were distributed in the cytoskeleton and muscle fibers, participating in muscle contraction, cell development, and myofibril assembly by exerting binding activity. The enriched KEGG pathways included tight junction, regulation of actin cytoskeleton, glycolysis/gluconeogenesis, AMPK signaling pathway, and HIF-1 signaling pathway. Our data suggest that S-nitrosylation of myofibrillar protein could be an alternative pathway of NO involved in the regulation of fresh meat quality. [ABSTRACT FROM AUTHOR]

• Myoglobin, lipid and protein oxidation occur concomitantly in cooled and cooked PSE chicken meat. • Thiol groups react with MDA, reducing the TBARS detection threshold in cooled PSE meat. • Metals and metmyoglobin are the main oxidative catalysts in cooled and cooked PSE meat. • Light plays a secondary role as an oxidative inducer in cooked PSE chicken meat. • Different pathways produce compounds from the interaction between oxidations in PSE chicken meat. The mechanisms involved in the development of oxidative changes in pale, soft, exudative (PSE) chicken meat during storage in the dark at 4 °C for 5 days and after cooking at 80 °C for 30 min, light exposure and reheating were explored in this study. The results indicate that myoglobin, lipid and protein oxidation occurred concomitantly during both treatments in PSE chicken meat during storage, and each process seemed to promote the others. Transition metals and metmyoglobin played pivotal roles in the generation of free radicals that triggered lipid and protein oxidation in cooled and cooked PSE, respectively. In contrast, light played a secondary role as an oxidative inducer of these processes. Different pathways triggered the production of compounds from the interactions between oxidative reactions in cooled and cooked PSE chicken meat. The impact of these reactions on the functionality of PSE chicken meat requires further study. [ABSTRACT FROM AUTHOR]

Porcine stress syndrome (PSS) is a genetic disorder caused by a recessive mutation in the halothane (HAL) gene and results in sudden death of pigs when placed under stress during transport and pre-slaughtering conditions. Animals that are affected by this mutation tend to develop pale, soft and exudative (PSE) meat, which results in an economic loss. In South Africa, the frequency of the number of carriers (Nn) and recessive (nn) pigs has increased by 21% to 30% from 2000 to 2003. This study aims to determine the prevalence of the malignant hyperthermia (MH) gene in breeding boars at nucleus or seed-stock level, and the prevalence at commercial abattoirs across the South African pig industry. Results indicate a low number of carriers (Nn = 17) and recessive (nn = 1) pigs at seed-stock level. For commercial abattoirs, 96.4% of the pigs tested did not carry the mutation. The low incidence of the MH mutation from breeding stock should eliminate a contributory factor to PSE meat in South Africa. Transport over long distances to abattoirs may ultimately have an effect on pork obtained even from non-carriers of the MH mutation. [ABSTRACT FROM AUTHOR]

The PSE (pale, soft and exudative) meat condition alters the color, the texture and the flavor of pork,increasing its acidity and occasioning low water retention, low nutritional level and rejection by the consumer. To determine the presence of the PSE characteristic, the pork carcasses are evaluated by pH measurements at 45 minutes (pH45) and 24 hours (pH24 after the slaughter of the pigs. The mean pH45 values indicate that 33.65% of the carcasses present the PSE condition, 47.12% are Normal and 19.23 % can be described as DFD (dark, firm and dry). The pH24 values indicate an increase in the PSE carcasses up to 68% while the normal and DFD ones decrease to 31.23 % and 0.77%, respectively. Comparing the change of the meat characteristics from 45 min to 24 hours, after the pig slaughter , it is observed that 62.44% of the normal meat and 87% of DFD one become PSE meat and 94.85% of the initial PSE one does not suffer any transformation. The pork carcasses present high incidence of the PSE characteristics at 45 minutes as well as 24 hours, indicating that there is problems before and after the slaughter of the pigs. High statistically significant difference (P ≤ 0.01) is found for the three meat conditions evaluated at pH45 and pH24.

Fifteen meat samples collected from pigs (Neckar hybrid line) were selected from 75 animals on the basis of their technological quality traits, and the samples were classified as normal, PSE, and acid meat. Sensory analysis was performed on the three meat categories. Total meat protein and drip loss protein were analyzed by electrophoresis (SDS-PAGE), mass spectrometry, and image analysis. From a sensory point of view, PSE meat was characterized by lower color intensity, and acid meat was characterized by the lowest score of juiciness. Certain soluble proteins derived from the drip loss were associated with meat quality, especially phosphoglucomutase and the B chain of hemoglobin in the case of PSE and acid meat. Low quantities of myofibrillar proteins (myosin LC1, troponin T (TnT) and troponin C (TnC)) in meat with high glycogen levels and low pH levels resulted in a higher rate of proteolysis of myofibrillar proteins due to higher enzymatic proteolysis activity in the meat. The results of this study showed that the TnC/TnI ratio may be a pertinent marker of postmortem muscle metabolism and that this ratio is related to textural properties. [ABSTRACT FROM AUTHOR]

Abstract: Climate change could affect meat quality in two ways. First, there are direct effects on organ and muscle metabolism during heat exposure which can persist after slaughter. For example heat stress can increase the risks of pale-soft-exudative meat in pigs and turkeys, heat shortening in broilers, dark cutting beef in cattle and dehydration in most species. Second, changes in livestock and poultry management practices in response to hazards that stem from climate change could indirectly lead to changes in meat quality. For example, changing to heat-tolerant Bos indicus cattle sire lines could lead to tougher, less juicy beef with less marbling. Also, pre-conditioning broilers to heat stress to encourage better survival during transport could lead to more variable breast meat pHult. The impacts that short term climate change could have will vary between regions. The ways the impacts are managed need to be based on experience while appreciating the range of approaches that could be used. [Copyright &y& Elsevier]

The effects on eating quality and meat quality of two different forms of post-slaughter treatment, performed in an abattoir, were studied in carriers and non-carriers of the RN− allele. Carcasses were subjected to rapid and slow chilling, and pelvic and Achilles suspension in a factorial experimental design. A temperature of 10 °C was achieved in the centre of M. longissimus dorsi (LD) within 3.5 h in rapidly chilled carcasses and within 8 h in slowly chilled carcasses. In deep M. semimembranosus (SM) a temperature of 10 °C was achieved within 11.5 h in rapidly chilled carcasses and within 14 h in slowly chilled carcasses. LD from slowly chilled RN− carriers suspended by the pelvis exhibited the greatest tenderness, while LD from rapidly chilled non-carriers suspended from the Achilles tendon exhibited the lowest tenderness. Pelvic suspension or slow chilling of non-carriers produced the same improvement in tenderness, and when combined the tenderness increased further. However, the tenderness of the RN− carriers was already high, and no significant improvement was seen following any of the studied post-slaughter treatments. Pelvic suspension prevented shortening of muscle fibres, as seen by longer sarcomeres in LD from pelvic-suspended sides. However, longer sarcomeres were associated with greater tenderness only in LD from non-carriers of the RN− allele. The presence of the RN− allele and a slow chilling regime increased the rate of pH decline in LD. Achilles suspension also increased the rate of pH fall in SM, in addition to the RN− allele and slow chilling. The overall tenderness of LD was mainly related to the course of pH decline during rigor; lower pH values between 3 and 7 h post-mortem contributing to greater tenderness. The myofibrillar length was predominantly related to RN genotype and was shorter in RN− carriers than in non-carriers. The RN− allele and slow chilling contributed to higher evaporation losses and RN− carriers exhibited increased frequency of PSE meat in the ham muscles. The use of pelvic suspension appears advantageous over slower chilling, since it improved tenderness without any negative influence on drip loss, evaporation or cooking loss. [Copyright &y& Elsevier]

The effects of crossbreed and of RN phenotype on pork and its eating quality were evaluated in four different pig crossbreeds [involving Swedish Landrace (L) × Yorkshire (Y) sows and Hampshire (H), Duroc (D), Yorkshire (Y) or Hampshire × Yorkshire (HY) as the terminal sire]. Pigs from the LYH crossbreed were also classified as either carriers or non-carriers of the RN− allele. In the crossbreeds investigated, M. longissimus dorsi (LD) and M. semimembranosus (SM) from LYH were found to have the lowest pH as measured 24 h post-mortem (pH24 h). The low pH in the LYH crossbreed was due to the large proportion of RN− carriers it had (approximately 70%). The non-carriers of the RN− allele in the LYH crossbreed had a pH24 h close to that of LYD, LYY and LYHY. In a selected group of pigs (N=50), the ultimate pH in the ham muscles M. biceps femoris (BF), M. quadriceps femoris (QF), M. gluteus medius (GM) and M. semitendinosus (ST) was also found to be lower in RN− carriers of LYH than in the other crossbreeds. As determined visually, LYD had the highest frequency (2%) of pale, soft and exudative meat (PSE), in LD. Ham from RN− carriers of LYH had the highest frequency (23%) of PSE meat around the femur, indicating that when the pH is low, the deep musculature, in which the chilling rate can be slow, is particularly sensitive to the development of PSE. According to assessments by members of a trained sensory panel, tenderness was significantly greater in LD from carriers of the RN− allele in LYH than in LD from LYD, LYHY and non-carriers of LYH. The tenderness of LD from LYY was rated as intermediate. The intramuscular fat content was found to be highest in LD from LYD, no relationship between intramuscular fat content and tenderness being found. The RN− carriers of LYH received the highest ratings in terms of juiciness. In conclusion, the sensory ratings demonstrated the great eating quality of LD from carriers of the RN− allele, indicating that abandoning the Hampshire crossbreed or eliminating the RN− allele from it, would result in the meat being less tender. [Copyright &y& Elsevier]