Tail-docking and tail biting in pigs: Findings at the slaughterhouse in Portugal

Abstract

Tail-docking is not accepted by European Union legislation as a routine measure to prevent tail biting in pigs. As part of systematic monitoring of animal welfare there is an increasing interest in recording tail damage in pigs at slaughter to identify problem farms. Tail biting lesions have been associated to causes of total condemnation in postmortem meat inspection. The goals of this study were to assess tail-docking and tail biting in slaughter pigs and to evaluate the association of tail lesions with meat inspection findings. The study was carried out at four pig slaughterhouses in the north of Portugal. Data was collected at the batch level during checks on food chain information, and at ante- and postmortem meat inspection. A total of 196 batches were screened. These batches covered 10,146 pigs: 4090 weaners (132 batches from 62 farms) and 6056 finishing pigs (64 batches from 43 farms). Of all the 196 batches, 88% were classified as tail-docked, corresponding to 100% of batches of finishing pigs and 83% of weaners. Tail lesions were scored according to a 3-level scale. During postmortem inspection, 84% pig carcasses (8566 out of 10,146) presented absence of tail lesions. Mild to moderate tail lesions (13%) were more frequent than severe ones (3%). Tail lesions, both mild and severe, were more prevalent (P>0.001) in weaners (13.1%, 3.5%) than in finishing pigs (12.7%, 2.1%). A total of 169 (1.7%) carcasses were condemned during postmortem inspection with the prevalence being higher in weaners (3.3%) than in finishing pigs (0.6%). The most frequent causes were poor body condition (31.4%), arthritis/polyarthritis (28.4%), and peritonitis (20.1%). No association between severity of tail lesions and postmortem condemnations was observed at the batch level, however a tendency for a higher proportion of postmortem condemnations in docked batches was found among weaners (P = 0.013). Further research with increased sample size and the analysis performed at the animal level is needed in order to confirm the observed tendencies. Recording information on tail lesions at the slaughterhouse is useful to gain information about general herd health, to support risk-based meat inspection and to assist farmers in welfare management plans.