Moroki, Y. 2020. Impact of flooring type on the sham dustbathing behaviour of caged laying hens. Applied Animal Behaviour Science 230, 105066.

Feed particles are preferred for foraging and they are also a stimulus for sham dustbathing. Most sham dustbathing bouts start with bill raking in the feed by caged hens. As hens often exhibit a floor scratching behaviour, an element of both sham dustbathing and foraging, by moving their legs back and forth while kicking the substrates before and after bill raking in the feed, some stimuli exerted on their legs might promote floor scratching behaviour. Therefore, the aim of this study was to test the effects of four types of floor stimuli at feed trough side on sham dustbathing. Behaviours performed just before sham dustbathing were also simultaneously examined. Commercial White Leghorn pullets were transferred to the poultry house and housed in simplified furnished cages at 17 weeks of age. Experiments with floor stimuli began when hens were 70-week-old. In total, 48 hens that had been reared on a wire floor without litter were tested. Four groups of three hens were taken from their furnished home cages and introduced to four non-furnished experimental cages. One-third of the floor of wire mesh at feed trough side was covered with one of the four floor stimuli: net, artificial turf, wooden board or draining board. Two groups were tested with one of floor stimuli, while the other two were used as controls for 2 days; then, the treatments were switched so that all the birds received both control and floor stimulus treatments. When hens were provided with a net, floor scratching behaviours were significantly increased (P < 0.05), stimulating bill rakes and other bouts of sham dustbathing. Floor scratching behaviours were also strengthened after treatment with an artificial turf. Fifty and thirty percent of the behaviours exhibited 1 min before sham dustbathing comprised resting and preening behaviours, and feed-related behaviours, respectively. These results suggest that some floor materials could promote floor scratching behaviours by stimulating a tactile sensation for their legs. The hens had exhibited sham dustbathing in feed in their home wire-floor cages; therefore, previous experience of sham dustbathing and observation of other hen during resting and preening may influence the hens to react sensitively and start sham dustbathing themselves. Feeding, foraging and sham dustbathing are supposed to reinforce each other; therefore, feed-related behaviours observed just before sham dustbathing might account for the close relationship among feeding, foraging, and sham dustbathing.