Intact Tails as a Welfare Indicator in Finishing Pigs? Scoring of Tail Lesions and Defining Intact Tails in Undocked Pigs at the Abattoir

Abstract

Tail biting lesions are a potential measure of on-farm animal welfare, as a large range of stressors increase the risk for tail biting outbreaks. Further, tail biting is a major challenge, as lesions due to tail biting decrease animal welfare and health, as well as production efficiency and carcass quality. The aim of this study was to suggest a tail scoring system for use at slaughterhouses processing undocked pigs, and to link tail lesion scores to meat inspection data. A further aim was to suggest a definition for an intact enough tail. To validate the suggested scoring system we assessed tails before and after scalding and compared results to pathological examinations. In total, 14,433 tails were scored, and 117 tails were collected for pathological examination. After scalding, 49.2% of all tails were scored as fully intact. Of tails with lesions 2.5% were scored as having major acute wounds (>2 cm), while 11.6% had minor acute wounds (<2 cm), and 36.7% healed lesions. Intact tails were on average 31.5 cm (SD 2.5 cm) long. Lesion scored at the slaughter-line agreed well with the pathological assessment. Tail lesions were associated with several meat inspection findings: tails with more severe lesions and of shorter length increased the risk for meat inspection findings to a higher degree. A detailed lesion scoring method helps to identify carcasses at risk for condemnations, as well as being a potential method for on-farm welfare estimation. We suggest that a system for scoring tail lesions in undocked pigs should utilize a combination of scoring of the lesion and measuring the tail length. As bite marks or bruises on an otherwise intact tail were not a concern for meat hygiene, we suggest the definition of an intact enough tail could allow the inclusion of tails with these mild changes. Meat inspection findings in carcasses with tails scored as healed, but with no fresh lesions, and with more than 75% of the average intact length remaining were rather similar to those of fully intact tails. Based on these findings we suggest that a tail of this length, and with no visible fresh lesions could also be considered intact enough.

Can increased dietary fibre level and a single enrichment device reduce the risk of tail biting in undocked growing-finishing pigs in fully slatted systems?

“…The severity of damage and the freshness of blood present were each scored on a 0 (optimal) to 3 (worst) scale. Based on findings of a positive correlation between the length of tail loss and risk of infections [ 27 ], if severely bitten tails were shortened, a tail amputation score was allocated based on a visually estimated level of amputation (0: no amputation, 1: remaining tail longer than around 50% of the original length, 2: remaining tail length between 25–50% of the original length, 3: remaining tail shorter than 25% of the original length). Ear lesions were scored on a 0–4 scale described in [ 13 ].…”

Abattoir-Based Measures to Assess Swine Welfare: Analysis of the Methods Adopted in European Slaughterhouses

“…Although animal welfare assessments based on abattoir outcomes have some advantages, on the other side, such systems may harbor some limitations [ 22 ]. These limitations are caused by different factors, such as the applications of different scoring systems that make difficult the comparison between multiple studies, the differences between countries in the application of animal welfare policies, and the applicability of some methods in high-speed slaughter lines [ 10 , 19 , 26 , 92 ]. As already mentioned, the use of MI data as indicators of animal welfare has been recently introduced.…”

“…Currently, the different scoring methods utilized to assess swine welfare at the slaughterhouse level makes the comparison between studies sometimes difficult [ 26 , 92 ]. In addition to this, a certain rate of discrepancy in the assessment of lesions between observers may not provide reliable information, as previously reported [ 60 ].…”

“…The development of camera-based systems could allow a better standardization and validation of the results obtained from pig welfare assessment, as advocated by Valros et al [ 26 ]. As far as antemortem activities are considered, the monitoring of the skin temperature of pigs at the slaughterhouse was also suggested as a method to detect pigs with severe tail lesions, but also to find the early onset of severe diseases such as the African Swine Fever [ 102 , 103 ].…”

“…Moreover, such lesions can be practically recorded during post-mortem MI activities and eventually, they may be embodied in a recording system for pig health and welfare monitoring purposes together with other organs score (e.g., pluck lesions). Of note, the detectability of certain lesions, such as tail or skin lesions, increases after scalding and dehairing of carcasses [ 25 , 26 ]. Therefore, the precise moment in which the record is performed is crucial.…”