Laying Hen Perch Use and Bone Health: Key Welfare Science

Perch use in laying hens serves critical welfare functions including bone health maintenance, normal roosting behaviour, and predator avoidance instinct expression. Understanding the science guides better cage-free housing design.

Key Facts

Laying hens have a strong motivation to roost at height — in the wild and in natural conditions, hens roost in trees or elevated structures every night, positioning themselves above potential ground-level predators
Perch use significantly improves bone mineral density in laying hens — hens with perch access have 40–60% greater ulna bone strength than floor-housed hens without perches
Keel bone fractures are paradoxically more common in aviary systems with perches than in systems without, because hens must land on and take off from perches — poor perch design increases collision and fracture risk
Perch material, diameter, positioning, and surface texture all affect whether hens can grip effectively, whether they slip, and whether their keel contacts the perch edge on landing
Round perches of 3–4 cm diameter, covered with rubberised material, positioned with adequate fly-in space, significantly reduce keel bone fractures compared to square-edged or smooth perches at the same height
Research shows that hens trained to use perches as chicks have higher perch use rates as adults — early-life experience shapes adult perch use behaviour
Perch space allocation matters: insufficient linear perch space forces competition and prevents all hens from roosting simultaneously, leaving subordinate individuals on the floor

Welfare Considerations

Perch welfare in laying hens illustrates the complexity of welfare trade-offs in aviculture. Perches are clearly welfare-positive for bone health and behavioural expression of roosting motivation. Yet poorly designed perches in aviary systems have become a primary cause of keel bone fractures — the most prevalent and painful welfare problem in contemporary cage-free production. This apparent paradox resolves when perch design quality is considered: well-designed perches with appropriate diameter, surface texture, positioning, and adequate fly-in space reduce fracture risk while providing bone and behavioural benefits. The welfare imperative is not to provide perches of any description but to provide perches designed to enable safe, confident use. Research into perch design has identified clear specifications that reduce fracture risk — the implementation challenge is translating this research into industry standards and audit requirements that ensure perch quality rather than merely perch presence.

What You Can Do

Support certification schemes that include perch design specifications in their standards, not only perch presence requirements
Advocate for keel bone fracture monitoring requirements linked to perch design auditing in cage-free production systems
Support research into optimal perch design specifications and their widespread adoption across commercial aviary systems
Choose eggs from producers with verified keel bone management programmes that include appropriate perch design
Raise awareness that cage-free is not automatically high-welfare — enclosure design quality, including perch specification, significantly determines welfare outcomes