Gilts are motivated to exit a stall

Stalls (or crates) are still a common type of housing in the swine industry, despite public concern and regional legislation restricting their use. In this study, we examined the motivation of gilts to exit a stall. Sixteen stall-naïve gilts (Large White x Landrace) were locked for 60 min in a gestation crate that had been mounted with a novel apparatus allowing continuous monitoring (2 Hz measuring frequency) of the force applied to its back gate by the animal. Raw force measurements were low-pass filtered and discrete pushing events identified via local maxima. All gilts displayed some level of motivation to exit the crate, ranging from 41 to 173 in the number of pushing events, as well as exerting a maximum force applied from 124 to 645 N. A hierarchical cluster analysis applied to the median and interquartile range (IQR) of force generated during individual pushing events yielded two behavioural profiles. One group of eight animals was more active than the other. This group exhibited a greater number of pushes, recorded a higher maximum, median force and its IQR, as well as a shorter time interval between two pushes (all t-tests with a P < 0.05). While all these naïve animals worked to leave the stall, gilts displayed different motivation profiles in trying to exit the stall consistent with a reactive/proactive framework. Taken together these findings provide further evidence to support stall confinement as aversive to swine but highlight the complexities in understanding and improving pig welfare.