Pettersson, I. C., Weeks, C. A., Nicol, C. J. 2017. The effect of ramp provision on the accessibility of the litter in single and multi-tier laying hen housing. Applied Animal Behaviour Science 186, 35-40.

Level changes in commercial laying hen loose-housing systems may be physically difficult for birds to negotiate, preventing or limiting access to resources such as the litter area and the outdoor range, and potentially increasing injury risk. The aim of this research was to investigate bird behaviour at an important level change (traversing between the raised slats/first tier and the litter), and whether it was affected by ramp provision or system. Birds were either observed at the edge of a single-tier with a full width ramp (ST-R), or at a section of tier edge without ramp in multi-tier systems (MT-NR) or in single-tier systems (ST-NR), both equipped with no ramps or only intermittent ramps throughout. Compared with single-tier systems, a greater proportion of birds that showed an initial orientation towards the litter moved away without traversing in the MT-NR group (p<0.05). Traversing birds in group ST-R showed reduced incidences of behaviours indicative of hesitancy/difficulty. The behaviours that occurred significantly less frequently in group ST-R compared with both groups MT-NR and ST-NR were crouching (p<0.01), multiple crouches (p<0.01), pacing (p<0.05) and stepping on the spot (p<0.01). Multiple head orientations were lower in ST-R compared with ST-NR (p<0.05). We conclude that the provision of a full-width ramp between the raised slatted area in single-tier systems or first tier in multi-tier systems could improve bird welfare by increasing the ease of access to important resources.