Perching behaviour and perch height preference of laying hens in furnished cages varying in height

Abstract

1. The objective was to investigate the effect of cage height on perch height preference and perching behaviour in laying hens. Twelve groups of two hens and 12 groups of 14 hens were tested in furnished cages equipped with two wooden perches. These stepwise perches were designed such that hens could choose between 7 different heights (6, 11, 16, 21, 26, 31 and 36 cm). Day- and night-time perching behaviour was observed on 4 consecutive days with a different cage height each day: 150, 55, 50 and 45 cm. 2. Given that a minimum perch-roof distance of 19 to 24 cm was available, hens preferred to roost on the highest perches at night. 3. Lowering cage height not only forced hens to use lower perches, but also reduced time spent on the perches during the day (two-hen and 14-hen test) and night (14-hen test). Moreover, it affected daytime behavioural activities (more standing and less preening) on the perches in the two-hen tests (but not in the 14-hen tests). 4. During the day lower perches were used more for standing and walking, higher perches more for sitting and sleeping. This behavioural differentiation was most pronounced in the highest cages. 5. Perch preference and perching behaviour depend on both the floor-perch distance and the perch-roof distance. Higher cages provide more opportunity for higher perches (which hens prefer), for better three-dimensional spacing (and consequently reduced density at floor level) and for behavioural differentiation according to perch height.

Scientific Opinion on welfare aspects of the use of perches for laying hens

“…However, the latter study reported more sitting behaviour as a proportion of perch usage on higher perches than on lower perches. Struelens et al (2008b) found that hens were more likely to roost on the highest perches (range 6-36 cm) at night. They also investigated the relationship between perch height and the height of the ceiling (range 150-45 cm) and suggested that use of the highest perches was hampered by ceiling distances of 24 cm or less.…”

“…Provided there is a minimum distance of approximately 20 cm between the top perch and the cage roof, hens prefer to roost at night on the highest perches available over a range of 6 to 36 cm (Struelens et al, 2008b). However, cage heights of less than 55 cm removed the preference for the highest perches, reduced perch use overall and reduced the amount of comfort behaviour performed on the perch.…”

“…Legislation requires the height of an enriched cage to be no less than 45-cm high in the lowest part, and this is a limiting factor for the maximum height at which perches can be placed while still providing sufficient head space for the hens to perch comfortably. It has been shown experimentally that a reduction of cage height from 55 to 45 cm affects perch preferences, forcing hens to use lower perches and reducing perch use (Struelens et al, 2008b). Therefore, having less than 20 cm between the highest perch and the ceiling could restrict access to the highest perch.…”

“…In non-cage systems, greater utilisation rates have generally been reported for high perches than for low perches during the daytime (Newberry et al, 2001). However, for caged hens, the tendency to avoid contact with the cage roof has a greater effect on daytime perching than on nighttime roosting (Struelens et al, 2008b). Indeed, in cage environments, non-elevated perches can be preferred for daytime use (e.g.…”

“…Because of the rather low number of papers, this descriptive analysis was not able to account for lack of independence, differences in sample size and other important sources of heterogeneity. Three papers (Struelens et al, 2008b;Tuyttens et al, 2013;Chen et al, 2014) referred to cage systems and the three others (Cordiner and Savory, 2001;Newberry et al, 2001;Brendler et al, 2014) referred to non-cage systems.…”