Tail posture as a detector of tail damage and an early detector of tail biting in finishing pigs
By Mona Lilian Vestbjerg Larsen, Heidi Mai-Lis Andersen, Lene Juul Pedersen
Applied Animal Behaviour Science
• A tucked tail worked as a detector of tail damage in finishing pigs.
• Tail posture seemed promising as an early detector of tail biting in finishing pigs.
• Tail posture was affected by risk factors of tail damage.
The purpose of the current study was to investigate the relation between the tail posture of finishing pigs and tail damage with the aims to use tail posture as (1) a detector of tail damage, (2) an early detector of tail biting to possibly predict and prevent bleeding tail damage. Tails of each individual pig (from 112 finishing pigpens) were scored three times per week for the full study period of 10 weeks. For the first aim, tail posture was observed directly in the stable three times per week, just prior to tail scoring, and pigs with a tucked tail were related to their tail scoring. The odds of being scored with a tail wound (both bleeding and non-bleeding) increased by almost sixfold if the pig was also observed with a tucked tail on the same day. More precisely, 28% of the pigs with a tucked tail were also scored with a tail wound, whereas this was only the case for 5% of the pigs with a different tail posture. This relation between a tucked tail and tail damage was larger than previously found in weaners and suggests that a tucked tail could be used as a detector of tail damage, although with the risk of many false identifications of tail damage. For the second aim, tail posture was observed from video the last 3 days prior to bleeding tail damage for case pens (n = 20; at least one pig with a bleeding tail wound) and their matched controls (n = 20). The number of pigs with lowered tails (below the tail root) was observed by scan sampling during 6 h per day. A generally higher probability of having a lowered tail was seen in the case pens compared to the control pens, but the probability of having a lowered tail did not increase prior to bleeding tail damage. Thus, the results indicate that tail posture is a promising early detector of tail biting in finishing pigs, but observations going further back than 3 days from bleeding tail damage are needed to find out when the difference in tail posture arises. Alternatively, a less severe definition of tail damage could be used. Further, the differences found were relatively small, and thus to be able to predict pens in future risk of tail damage from changes in tail posture would probably demand the development of an automatic recording method for the number of lowered tails at pen level.