Artificial lighting has enabled improvements in egg production, and different types of light and wavelengths have been tested to achieve better production results in the past. It has been established that red light positively affects the laying performance of hens when such a lighting programme is applied prior to sexual maturation. However, few studies have investigated the effects of light colour on the performance of laying hens during the final stages of production. This study examined the effects of supplementing natural light with white or red lighting during the autumn–winter season on the laying performance, feed intake, average egg weight, egg mass, and feed conversion per egg of laying hens, and the albumen height, yolk colour, and Haugh units of their eggs. The effects on shell thickness, shell strength, body mass, ovary weight, and oviduct weight were also assessed. A total of 7680 70-week-old Lohmann LSL laying hens housed in four California-type sheds were used in the study. Hens exposed to the white light treatment had significantly heavier ovaries; however, no significant differences between red and white lighting were found among the other evaluated variables.

(Submitted 11 May 2025; Accepted 30 September 2025; Published 14 October 2025)