Do Pigs Like to Brush? An Observational Study of Pig Brushing Behaviour in a Commercial Production Environment

Niclas Högberg^1*Lena Skånberg²Oleksiy Guzhva³Rebecka Westin⁴Axel Sannö¹Anna Wallenbeck²Maria Vilain Rørvang³

• ¹Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
• ²Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences, Uppsala, Sweden
• ³Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
• ⁴Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences, Skara, Sweden

In semi-natural environments, pigs have been observed rubbing or scratching against trees and bushes, and in commercial settings they often rub against pen structures and may allow handlers to scratch them. While human-applied scratching of pigs has been studied, little is known about their self-scratching behaviour. Research on brush use in cattle suggests potential welfare benefits, while research on brushing behaviour in pigs is, to the best of our knowledge, absent. To address this gap, this study investigated whether gestating sows use a mechanical brush when housed in a social setting, how brushing varied in duration, frequency, body region, and time of day, and whether individuals differed in use. The study was conducted on 29 loose-housed gestating Yorkshire-sows with access to deep straw bedding, a transponder-controlled feeder, and a mechanical brush (Comfort Pig, Comfy-Solutions B.V., The Netherlands). Observations included 192 h of continuous video recordings covering the brush area. An ethogram adapted from cattle studies and refined for pigs was applied to record brushing, sniffing, oral manipulation, and displacements. Brushing was further categorised by body region, initiation, intensity, and duration. Data were summarised descriptively, and differences between groups, times, and individuals were tested with non-parametric methods. All sows engaged in brushing at least once, during the study, averaging of 1.5 (IQR 1–2) bouts per day. Median bout duration was 12 s (IQR 8–17), with active brushing comprising nearly half of total time. Brushing was mainly directed to the middle body region (29.8 %) and often initiated at the head (46.2 %). No consistent diurnal pattern was evident. Sniffing preceded brushing in 85 of the 297 observed brushing bouts, while oral manipulation was only observed 5 times. Incomplete bouts and occasional displacements (3% of bouts) suggest that internal and social factors may influence access. Taken together, this study provides an initial systematic description of brushing behaviour in pigs and suggests that mechanical brushes may serve as an enriching resource for pigs in production. Further research, including comparisons across different brush types, production stages, pig-to-brush ratios and housing systems, is needed to evaluate their potential as welfare-enhancing tools in commercial pig production.