Lighting conditions in broiler chicken houses significantly affect bird welfare through their effects on behaviour, activity levels, eye health, and sleep. Evidence-based lighting standards represent an achievable improvement for millions of birds with minimal cost implications.
Lighting management in broiler houses is a relatively low-cost welfare intervention that has been systematically avoided in conventional production because continuous lighting marginally increases feed conversion. The welfare cost of this choice is real: continuous or near-continuous lighting disrupts the circadian rhythms that broilers share with all birds, causes progressive eye pathology, prevents the rest that growing birds need, and contributes to the leg problems that are endemic in fast-growing breeds. Minimum six-hour dark periods — as required in EU enriched housing — are a simple, essentially cost-free welfare improvement that industry resistance has kept out of standard practice in many systems. Consumer and certification body pressure for mandatory dark periods is one of the most straightforward and impactful lighting welfare improvements available.