A Comparison of Conventional Lighting Versus Poultry-Specific Lighting During the Day in Combination With or Without a Blue Light “Moonphase” at Night

Lighting is a key environmental factor influencing the welfare and productivity of laying hens; however, the combined effects of poultry-specific daytime spectra and dim blue “moonlight” during the scotoperiod remain poorly characterized. This study aimed to evaluate the effects of spectral modification of daytime lighting and the use of dim monochromatic blue light at night on stress, fear, leg health, egg production, egg quality, and feeding activity in aged laying hens. One hundred and twenty 70-wk-old laying hens were assigned to one of four lighting treatments, arranged as a 2 × 2 factorial of daytime spectrum × night-time condition, for 28 d following a 14-d acclimation under common lighting: conventional 3000 K white LEDs (CON); poultry-specific lighting (PSL) combining 3000 K white LEDs with 630 nm red light; CON with dim monochromatic blue light at night (CON-moon); and PSL with dim monochromatic blue light at night (PSL-moon). Plasma corticosterone, heterophil-to-lymphocyte (H/L) ratio, composite asymmetry, tonic immobility, inversion response, tibial breaking strength and bone ash, egg production, egg quality, and AI-quantified feeding activity were measured. By the end of the treatment period, hens under PSL had lower corticosterone concentrations, lower H/L ratios, and less physical asymmetry than hens under conventional light, together with taller albumen and higher Haugh unit values, and they spent less time at the feeder without eating less. Moonlight at night produced a further reduction in the stress indicators and, by the final sampling, heavier eggs with stronger shells. Hen-day egg production and tibial breaking strength were unaffected by lighting. These findings indicate that poultry-specific lighting paired with dim blue moonlight is a practical, noninvasive enrichment strategy that can simultaneously improve welfare and egg quality without compromising production.