Night-time roosting in laying hens and the effect of thwarting access to perches

Free-living hens roost on branches in trees at night, and laying hens in av iary systems or cages provided with perches also make extensive use of thes e for night-time roosting. It is therefore suggested that roosting on perch es is important to the hens and that domestic hens should be provided with perches in order to promote welfare. However, no study has addressed the qu estion of motivation for roosting. In the present experiment, we studied un disturbed roosting behaviour and the reaction of commercial laying hens whe n roosting on perches was thwarted. Fifty-two adult hens (Lohmann Selected Leghorn, LSL) were kept in two groups of 26 hens in litter pens with perche s at heights of 23, 43 and 63 cm. Behaviour was observed for 60 min startin g at lights-off, registering the number of hens on each perch level. The he ns started to get onto the perch immediately and within 10 min after lights -off, more than 90% of the hens were on the perch. All hens roosted close t ogether on the top perch. In a second experiment, 24 hens were kept in eigh t groups of three birds each in experimental pens equipped with perches. Bi rds were tested in four different situations: (1) the pen unchanged (Base), (2) the perch covered with plexiglass (PCov), (3) the perch removed (PRem) and (4) the unchanged pen (Post). The order of PCov and PRem alternated be tween groups in a balanced manner and all groups of birds experienced all f our treatments. The hens were observed for 60 min from lights-off using foc al sampling. For comparisons, the Post treatment served as the control. In the treatments where perching was not possible, the hens spent less time si tting(p = 0.042), and also tended to spend more time standing (p = 0.06), t han in the control. Furthermore, the hens moved more (p = 0.042) when the p erch was inaccessible, and when the perch was visible but inaccessible they also showed more attempts to take off (p = 0.042). These findings can be i nterpreted as increased frustration and/or exploration, probably to find an alternative roosting site. Together with the high use of perches for night -time roosting under undisturbed conditions, these results indicate that la ying hens are motivated to perch and imply that hens kept under conditions where perching is not possible may experience reduced welfare. (C) 2000 Els evier Science B.V. All rights reserved.