Slaughterline records of various postmortem pathological lesions and their influence on carcass and meat quality in slaughtered pigs

Association between Enzootic Pneumonia-like Lung Lesions and Carcass Quality and Meat pH Value in Slaughter Pigs

Although the prevalence of respiratory diseases in slaughter pigs ranges from 19% to 74% and continues to be an important concern for swine herds worldwide, only a few studies have investigated the relationship between respiratory disease and pork quality. The general aim of this study was to investigate associations between the prevalence and severity of enzootic pneumonia-like lesions in Polish slaughter pigs on different carcass and meat-quality characteristics at the animal and herd levels. The average prevalence of bronchopneumonic lungs with different degrees of lesions was 94.57%. The majority of lesions indicated the acute stage of enzootic pneumonia. Our results indicate a statistically significant interaction between the mean weight of carcasses depending on the extent of the lesions (p = 0.04) at the animal level. The correlation between meatiness and severity of lung lesions was r = -0.25 (p = 0.00). The correlation between the extent of lung lesions and pH₄₅ value was r = -0.17 (p = 0.005) on the animal level and r = -0.63 (p = 0.017) at the herd level. This implies that lung lesions in slaughter pigs negatively influence not only animal health and welfare, but also carcass quality.

Review on the methodology to assess respiratory tract lesions in pigs and their production impact

Porcine respiratory disease is one of the most important health problems in pig production worldwide. Cranioventral pulmonary consolidation (CVPC) and pleurisy are the two most common lesions in the respiratory tract of slaughtered pigs. The present review paper discusses pathogens involved in the lesions, lesion prevalence, scoring systems, advantages and disadvantages of slaughterhouse examination, and the impact of CVPC and pleurisy on performance, carcass, and meat quality. Cranioventral pulmonary consolidation and pleurisy in slaughter pigs are characteristic for infections with Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae, respectively, although other pathogens may cause similar lesions and/or be involved in their development. The overall prevalence of CVPC and pleurisy in slaughter pigs are still high, being the prevalence of CVPC generally higher than that of chronic pleurisy. The advantages and disadvantages of slaughterhouse examination are discussed in relation to practical aspects, the assessment of lesions, the number and representativeness of the examined animals and the interpretation and value of the results for the stakeholders. The main scoring methods for CVPC and pleurisy are shortly reviewed. In general, scoring methods can be applied rapidly and easily, although significant variation due to abattoir and observer remains. Artificial intelligence-based technologies that automatically score lesions and facilitate processing of data may aid solving these problems. Cranioventral pulmonary consolidation and pleurisy have a major negative impact on pig performance, and the effects increase the extension of the lesions and/or presence of multiple lesions. The performance losses caused by these lesions, however, vary significantly between studies and farms, possibly due to differences in study population and used methodology. Both lesions also have a negative impact on different carcass and meat quality parameters, leading to increased risk for poor processing and storage of the carcasses. Monitoring lung lesions of slaughter pigs should be optimized and implemented routinely; however, it is recommended to complement this information with farm data and laboratory results for specific pathogens.

Impacts of group stunning on the behavioral and physiological parameters of pigs and sheep in a small abattoir

This study investigated reactions of pigs (N = 148) and sheep (N = 77) to group stunning where animals were present for the slaughter of others. Mock stunning with an isolated animal was used as the control. In both species, there was little evidence to suggest a difference in blood glucose and cortisol with stun order (P ≥ 0.21). In pigs, lactate differed by stun order (P < 0.001). Control pigs had lower lactate than pigs stunned first (P = 0.009) likely due to longer rest time after pre-slaughter handling. Conversely, the control sheep had greater average lactate than other groups. However, due to limited sample size and large variation there was not enough evidence to conclude an effect of stun order on sheep lactate (P = 0.28). Overall, there was limited evidence of an impact of stun order on behavior. The last pigs stunned exhibited a greater likelihood of grunting compared with other stun orders (P ≤ 0.05).

Prevalence of fibrinous pericarditis in heavy pigs (170 kg) and its association with other pluck lesions at slaughter inspection

This study determined the prevalence of fibrinous pericarditis and its correlation with other pluck lesions in 658 batches of pigs from 236 intensive farms located in Northern Italy over a 12-month period. All pigs were slaughtered at 170 kg, and a total 57,943 plucks (approximately 90 pigs/batch) were individually assessed for the presence of fibrinous pericarditis, pneumonia, pleuritis, and liver milk spots. There was no seasonal variation in the prevalence of plucks with fibrinous pericarditis and annual mean prevalence was 5.6% (range, 0-26.3% at batch level; median, 4.71%). Farm of origin, evaluated as a random effect, accounted for 17.7% batch variation. Batches with a high prevalence of fibrinous pericarditis (≥7.7%) had higher prevalences of pleural, pulmonary, and liver lesions than those with low-middle prevalence of pericarditis; high prevalence of pericarditis was predictive of pluck lesions (P < 0.001). There was a highly significant association between fibrinous pericarditis and severe pleuritis, and 55% of plucks with the highest score for pleuritis also had ongoing fibrinous pericarditis, with a positive correlation at batch level (r² = 0.52; P < 0.001). The co-existence of pericarditis and pleuritis (73.5% of all pericarditis cases) suggests that pleuritis plays a role in the pathogenesis of pericarditis. Based on the prevalence fibrinous pericarditis, and the role of pleuritis as a potential comorbidity, abattoir data on pluck lesions with accompanying farm history, could aid the interpretation and management of on-farm health problems, and inform diagnostic protocols.

Biochemical, carcass and meat quality alterations associated with different degree of lung lesions in slaughtered pigs

This study examined the relationship between lung lesion severity and presence of antibodies of various respiratory pathogens, and the effects of lung lesion severity on growth performance, biochemical indicators, total aerobe counts, and carcass and meat quality indicators in total of 240 slaughter pigs originating from two farms with similar rearing conditions. Lung lesion severity was calculated based on the degree of pneumonia and pleurisy in slaughtered pigs. Two-step cluster analysis was used to place individual pigs to four clusters according to pneumonia and pleurisy scores: no lung lesions (cluster 1); mild lung lesions (cluster 2); moderate lung lesions (cluster 3); and severe lung lesions (cluster 4). ANOVA and post hoc pairwise comparisons using Tukey's test were performed to assess the differences between clusters in examined variables. Multivariate linear regression analysis was run to identify associations between lung lesions and examined variables. There was a strong evidence of association between the absence of lung lesions and increased albumin, sodium and chloride levels, daily weight gain, live weight, hot carcass weight, cold carcass weight, loin thickness and carcass lean content, and decreased haptoglobin, CK and LDH levels. Also, pigs without lung lesions produced the highest percentage of red, firm and nonexudative pork. Pigs having severe lung lesions had the highest percentage of simultaneously seropositive samples to SIV, PRRSV, PCV-2, PRCV, APP and M. hyopneumoniae. There was a strong evidence of association between the presence of severe lung lesions and decreased lactate, glucose, sodium, chloride and albumine levels, daily weight gain, live weight, hot carcass weight, cold carcass weight, loin thickness and carcass lean content, and increased CK, LDH and haptoglobin levels. There was a strong evidence of association between the presence of severe lung lesions in slaughered pigs and increased meat pH and sensory colour scores, and decreased drip, thawing and cooking losses and L* and b* values, which led to the highest occurrence of moderate DFD and DFD pork. There was a strong evidence of association between the presence of mild lung lesions in slaughtered pigs and decreased meat pH and sensory colour scores, and increased drip, thawing and cooking losses, L* and b* values, which led to the highest occurrence of moderate PSE and PSE pork. In conclusion, the presence of lung lesions, irrespective of severity, was significantly associated with alterations in the biochemical indicators, growth performance and carcass and meat quality in slaughtered pigs.

The effects of season on health, welfare, and carcass and meat quality of slaughter pigs

This study assessed the effects of season on health, behaviour, physiological stress parameters, and carcass and meat quality in a total of 480 slaughter pigs. The following health indicators were recorded: pneumonia, pleurisy, milk spots, and pericarditis. Behaviour was monitored during unloading (slipping, falling, turning back, reluctance to move, panting, shivering) and lairaging (panting, shivering, huddling). Blood lactate and glucose concentrations were determined at exsanguination. Performance indices (live weight, daily weight gain), carcass (carcass weight, backfat and loin thickness, lean meat content, carcass lesion score), and meat quality (pH, temperature, drip, thawing and cooking losses, colour, marbling) traits were measured postmortem. Pigs slaughtered in winter had the highest live weight, carcass weight, loin thickness, and carcass lesion score, while the lowest live weight, carcass weight, and backfat thickness were recorded in pigs slaughtered in summer. The highest lactate and glucose concentrations were recorded in pigs slaughtered in summer. The highest prevalence of red, soft, and exudative meat was recorded in pigs slaughtered in winter. Pigs slaughtered in summer had the lowest pH, the highest thawing loss, L* value, b* value, and occurrence of pale, soft, and exudative meat. Pigs slaughtered in autumn had the lowest drip loss, cooking loss, L* value, b* value, and the greatest percentage of red, firm, and nonexudative meat. In conclusion, the summer and winter temperatures compromised health and welfare and reduced carcass and meat quality in slaughter pigs, indicating that protection against heat and cold stress is not yet effective.