Tail-biting Outbreaks Research Articles

Rope test may indicate efficacy of tail-biting treatments in growing pigs

AbstractTail biting is a most serious welfare problem in pigs raised for slaughter. In instances of an outbreak of tail biting, scientists have recommended that farmers take measures such as removal of affected animals, provision of enrichment materials and application of repellents to the pigs’ tails. However, no scientific study has ever confirmed the efficacy of any of these suggestions in counteracting an ongoing outbreak. Here, the efficacy of two repellent ointments, Dippel's oil and Stockholm tar, were examined in a tail-chew test. For this, a novel piece of nylon rope was used as a tail model to measure biting behaviour semi-automatically in 24 single-sex groups of growing pigs (total 264 pigs). Repeated measures analysis showed no effect of time, gender or unit (12 pens per unit), but a highly significant effect of treatment, in that both Stockholm tar and Dippel's oil significantly reduced rope manipulation compared to controls. These results suggest that Stockholm tar and Dippel's oil may be effective in reducing tail biting. The approach taken may be valuable in further testing of strategies to reduce tail biting and improving pig welfare.

Non-nutritive Chewing by Pigs: Implications for Tail-biting and Behavioral Enrichment

Groups of six juvenile pigs were presented with chewable materials (braided cotton cord or rubber strips). The time spent chewing the materials was quantified over 48 h by time-lapse video recording. A 150 mm length of braided cord attracted considerable chewing (average of 30 min/day/pig) and the behavior caused much fraying and damage to the exposed end of the cord. However, the pigs chewed very little (2 min/day) on the same material when it was presented as a loop with no exposed end. Solid rubber strips, which were much less easily destroyed, attracted only half as much chewing as the cord, but a straight length with an exposed end was still chewed much more (average of 12 min/day/pig) than a loop (1 min/day). The amount of chewing on a loop of cord increased dramatically when a small cut was made to allow the material to be damaged more easily. This suggests that easily damaged materials attract much more chewing than less destructible ones, but even with relatively indestructible materials, the presence of an exposed end increases the amount of chewing. The results have implications for understanding tail-biting outbreaks and for behavioral enrichment of pig environments.

Electronic Sensing of Non-destructive Chewing by Growing Pigs

Non-destructive chewing (i.e., the normally harmless chewing performed by pigs on their pen-mates and surroundings) is considered to be the behavioral pre-cursor of tail-biting outbreaks. A simple method for monitoring this behavior was developed, based on a chewing sensor consisting of a canvas-covered tube and sealed air chamber. Compression of the tube by chewing causes an increase in air pressure that is detected by a pressure transducer and logged by a computer. Video recordings of pig behavior showed that activation of the sensor was caused almost exclusively by chewing and rarely by other activities. Hourly chewing counts by the sensor were closely correlated (r = 0.83) with oral behavior as detected by video recording of six groups of six pigs over 72 h. Chewing counts showed large differences between groups and between individual pigs. The behavior showed daily peaks at mid-day and late afternoon, corresponding to the animals’ diurnal pattern of general activity but not corresponding to feeding behavior.