Monitoring of the health status of slaughtered pigs by scoring of the pluck lesions

The evaluation of lung lesions at the slaughterhouse allows the monitoring of swine health and welfare and provides valuable data for epidemiological purposes [1]. The aims of this study were (i) to determine the prevalence of gross lesions at abattoir on the pluck of heavy weight pigs (~160 kg, 9 months of age) destined for PDO ham production and (ii) to investigate the correlation between the severity of lung and pleura lesions and carcass weight. The study was carried out in a slaughterhouse located in Northern Italy between December 2020 and March 2021. Enzootic Pneumonia-like lesions were assessed scoring each lung lobe from 0 to 4, with a maximum score of 28. Pleuritis lesions were evaluated using the Slaughterhouse Pleurisy Evaluation System (‘SPES’ score) with a maximum score of 4. Liver lesions were ranked from 0 to 2, relying on the number of milk-spot lesions. Other lesions such as pericarditis, lung scars and abscesses were also recorded. Data were collected from 73 batches coming from 63 farms, for a total of 7245 pigs. Descriptive statistics of the different lesions were performed at farm-level while the association between the mean value of lung and pleura scores with the mean value of the carcass weight was assessed using a linear regression at batch-level. A p-value ≤0.05 was considered significant. Overall, 60% of the lungs presented lesions with 98% of the EP-like lesions located in the cranio-ventral lobes. The average lung and pleurisy scores were 2.48±1.43 and 1.07±0.43, respectively, with 37% of the pleura presenting severe damage (score ≥3). The average liver score was 0.38±0.34, with 29% of the livers damaged. Pericarditis and lung scars values were 5% and 1%, respectively. The results of the mean values of the examined lesions were comparable to other previously reported in the literature [2]. No statistically significant correlation was found between the lung (R2 =0.007) and pleura (R2 =0.001) scores and the mean carcass weight at batch level. Such findings are in contrast with other studies reporting an effect of the respiratory lesions on the productive parameters [3]. These discrepancies may depend on the different scoring methods used in the studies, duration of the finishing stage and health management of the pigs. This study supports the evaluation of pluck lesions at the slaughterhouse for the monitoring of the health and welfare status in fattening pig farms.