Light management is one of the most influential environmental factors affecting poultry welfare. Lighting intensity, photoperiod, and light spectrum affect behaviour, activity levels, health, and productivity across all poultry species. Evidence-based lighting management is a key component of high-welfare production systems.
Why Lighting Matters for Poultry
Poultry vision differs substantially from human vision. Birds are tetrachromats (four cone types including UV-sensitive receptors) and perceive a wider light spectrum than humans. They use light intensity and photoperiod to regulate circadian rhythms, hormone cycles, reproductive behaviour, and activity patterns. Lighting in poultry housing profoundly shapes these fundamental biological processes.
Broiler Lighting Welfare Issues
Historically, broiler sheds were kept in near-continuous dim lighting (23 hours light/1 hour dark) to maximise feed intake and growth rate. Welfare consequences included:
- Disrupted circadian rhythms and sleep deprivation
- Reduced activity and exercise — contributing to musculoskeletal disorders
- Inability to distinguish normal day-night cycles — chronic disorientation
Current UK legislation requires minimum 6 hours of continuous darkness per 24-hour period. Higher welfare standards (RSPCA Assured) require ≥8 hours darkness and minimum 20 lux light intensity.
Light Intensity and Behaviour
Light intensity affects activity levels in broilers. Research demonstrates that moderate light intensity (20–40 lux) promotes walking, exploratory behaviour, and normal dustbathing compared to very dim light (<5 lux). Brighter light reveals more of the pen environment and stimulates social behaviour and foraging — important positive welfare indicators.
Natural Light Access
Windows and skylights providing natural daylight access offer important welfare benefits beyond simple illumination — the spectral quality of natural light (including UV components) allows normal visual function, better environmental perception, and possible immune benefits. Higher welfare standards increasingly specify minimum window area or access to natural light.
Laying Hen Lighting
Egg-laying in hens is photoperiod-dependent. Long days (16 hours light) stimulate LH release and ovulation. Lighting programmes manipulate the photoperiod to stimulate early lay and maintain production. Abrupt lighting changes cause stress — gradual transitions using dimmers are preferable. Enriched colony and free-range systems typically provide better natural light access than conventional cage systems.
Species-Specific Considerations
Turkeys, ducks, and other poultry species have species-specific lighting requirements differing from broilers and laying hens. Ducks, for example, are less dependent on photoperiod for egg production than chickens. Multi-species welfare standards must account for these differences in lighting management.