Associations between carcass tail lesions and other welfare conditions and the performance of negative behaviours in pigs

Tail lesions are outcomes of tail biting behaviour and reflective of impaired welfare in pigs. It is possible that tail biting is associated with other behavioural problems such as ear- or flank biting. Hence, the aim of this study was to investigate the potential of carcass tail lesions to reflect other behavioural problems on farms and thereby act as an ‘iceberg indicator’ for pig welfare.

Welfare assessments were conducted on 31 integrated pig farms by observing 18 randomly selected pens of 1st and 2nd stage weaner and finisher pigs (6 pens per stage). Pens were observed for 10 min and the number of pigs with tail, ear, flank and skin lesions was recorded. All occurrence behaviour sampling was used to record frequency of tail-, ear-, and flank biting (5 min). The average percentage of pigs in a pen affected by welfare lesions was calculated, as was the average frequency of behaviours per pig, in each production stage (mean ± SE). One batch of pigs from each farm was observed at the slaughterline and carcass tail lesions were scored according to severity (0 – 4). An average carcass tail lesion score for each batch was calculated. Spearman rank correlations were calculated between average carcass tail lesion score and the measured welfare conditions and behaviours.

All lesion types were observed in the 1st stage pens (tail: 5.4 ± 1.0%; ear: 9.4 ± 1.7%; flank: 0.4 ± 0.4%; skin: 4.8 ± 0.7% of pigs affected). The percentage of pigs with tail lesions in 2nd stage weaner pens was 6.2 ± 0.5% with the highest prevalence recorded in finisher stage pens (11.0 ± 0.8%). Similarly, flank lesions were more highly prevalent in 2nd stage weaner and finisher pens (1.4 ± 0.5% and 2.3 ± 0.5%, respectively). Ear lesions were most prevalent in 2nd stage weaner pens (15.4 ± 2.8%) with the lowest prevalence seen in the finisher pens (7.1 ± 1.3%). On average 204.3 ± 25.8 carcasses were scored per batch and average carcass tail lesion score was 0.83 ± 0.02 (range: 0.53 – 1.26). No correlations were found between carcass tail lesion score and the prevalence of tail/ear/flank lesions or frequency of tail/ear/flank biting behaviour for any of the production stages.

The high prevalence of ear and tail lesions throughout the production stages raises concern for pig welfare. No associations were found between carcass tail lesion scores and the abnormal biting behaviours or consequent lesions, suggesting that this measure might not be a useful ‘iceberg indicator’ for these aspects of pig welfare.

Disclosure of Interest: None Declared.