The multivariate approach identifies relationships between pre-slaughter factors, body lesions, ham defects and carcass traits in pigs

Abstract

Abattoir meat inspection has been proposed for the collection of welfare outcomes. The identification of suitable animal-based measures (ABM) is still a critical point that needs to be implemented to avoid collinearity among measures. The present study aims to benchmark the presence of ABM such as skin and tail lesions and ham defects in carcasses from 79 batches of Italian Heavy pigs and to identify possible relationships between the assessed ABM and pre-slaughter factors such as the season and the overnight lairage. Furthermore, the study also considers the effect of pre-slaughter conditions and ABM on carcass traits parameters (cold carcass weight and lean meat percentage). Skin and tail lesions were recorded at the slaughter line. The presence of abscesses, muscle tears and veining defects were assessed in the hams at trimming, according to the Parma Ham Consortium. A multivariate analysis was performed to identify relationships between ABM and pre-slaughter factor; therefore, a linear model was built to assess the effect on carcass weight and lean meat percentage. Main welfare issues were represented by skin and tail lesions and muscle tears (prevalence above 10%). Multivariate analysis evidenced that skin lesions and veining defects were mostly associated with the warm season. Abscesses and muscle tears in the hams were more likely related to overnight lairage, while tail lesions contributed equally to both season and lairage. Moreover, lairage related factors showed to affect lean meat percentage. The findings of the present study suggest that ham defects might be useful indicators of pre-slaughter stress. The validation of these findings with physiological parameters could be of interest for further studies.

Literature Review on the Pre-Slaughter Welfare of Italian Heavy Pigs

“…Another possible explanation is that, compared to other countries, Italian heavy pigs tend to have relatively short travel durations [18,19,21]. Similarly, another study [25] reported only one death at unloading on more than 10,000 heavy pigs inspected over 6 months in one Italian abattoir. However, before confirming the hypothesis that pigs in this certification production scheme benefit from lower mortality, this data should be systematically compared with those obtained from the same slaughterhouse on non-PDO pigs of the same age and body weight, and this information is hard to find as non-certified pigs are in the vast majority of cases slaughtered at a younger age and lighter bodyweight.…”

“…Some studies measured ham defects as a consequence of transport conditions. Some of these defects have been proposed as ABMs to assess the pre-slaughter conditions in heavy pigs, since they reflect injuries that occurred during pre-slaughter, for example hematomas, bone ruptures and muscle tears [ 24 , 25 ]. Arduini et al [ 15 ] reported a positive correlation between transportation length (i.e., distance) and ham defects.…”

“…Skin lesions can be assessed using different methods: as described in the Welfare Quality protocol [ 14 , 25 ] or using other scales [ 15 , 24 ]. The results differ between studies: some authors [ 25 ] did not find any association between skin lesions and overnight lairage, while others [ 15 , 24 ] observed increased lesions in the anterior part of the body after overnight lairage.…”

“…Skin lesions can be assessed using different methods: as described in the Welfare Quality protocol [ 14 , 25 ] or using other scales [ 15 , 24 ]. The results differ between studies: some authors [ 25 ] did not find any association between skin lesions and overnight lairage, while others [ 15 , 24 ] observed increased lesions in the anterior part of the body after overnight lairage. It is important to consider that these three studies used different scoring systems and that they were carried out in different slaughterhouses and different years, therefore under different management practices, as well as lairage conditions, and this can explain the different results among studies.…”

“…Studies available in the literature show conflicting results. On the one hand [ 25 ], increased abscess and muscle tear prevalence have been observed in hams from batches of pigs subjected to overnight lairage, suggesting that fighting might have led to increased slipping, and subsequent occurrence of muscle tears. According to the authors, overnight lairage may also exacerbate previous infective conditions.…”