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.