The influence of tail biting on pig carcasses considering different production systems and tail length

Tail biting is recognized as a major welfare issue in pig production, associated with great economic losses. The European Union has stated its position regarding tail docking practices through the Directive 120/2008/EC and Recommendation (EU) 2016/336. The directive encourages all Member States to establish standards for the protection of pigs as well as measures to reduce the need for tail-docking and tail biting prevalence. This study aims to evaluate tail biting occurrence in slaughtered pigs, analyse the association of tail lesions with production system and tail length, and explore the relationship between carcass condemnations and tail damage. Information on a total of 9189 pigs from 73 batches with different tail lengths (undocked, docked mid-length, fully docked) and from distinct production systems (conventional, conventional without the administration of antimicrobials, organic) was collected at a Spanish abattoir. Due to the speed of the slaughter line, it was only viable to classify a subset of 3636 animals regarding their tail condition, which was classified into three categories. Batches with higher lesion scores presented a greater chance of total condemnations (p=0.014, OR=1.81) and total condemnations by pyaemia (p=0.013, OR=2.96). The probability of observing tail lesions varied with tail length, with undocked pigs having higher odds of showing severe lesions when compared to the other tail lengths (p=0.0001, OR=3.11 and OR=2.10). When it came down to local condemnations due to abscess, tail length was also significant with docked at mid-length and undocked carcasses having higher odds of abscess condemnations than fully docked (p=0.0002, OR=2.10 and OR=1.70). Regarding husbandry systems, organic farms had a higher probability of total condemnation when compared to the other two production systems (p=0.0263, OR=2.27 and OR=4.36). This research concludes that there is a clear association between tail lesions and condemnation rates. As tail length influenced the severity of tail lesions, it is imperative to consider the impact of tail length on animal welfare and conduct further studies to determine if a longer resected tail could result in more favourable outcomes compared to a conventional docked tail. Although it is argued that pigs raised under less intensive production conditions (organic) have a higher level of animal welfare compared with pigs raised under conventional production, tail biting and systemic infections can still be observed in organically raised pigs.