Optimal light spectrum to laying hens

Abstract: Modern poultry farming still struggles with high levels of feather pecking in laying hens (Gallus gallus domesticus). This form of abnormal pecking behavior is known to be affected by multiple factors, including effects from the light environment. Illu-mination in poultry housing is in many ways different from the light environment from the ancestor of the chicken – a species that has one of the most advanced visual systems and is able to see into the ultraviolet range. This study performed two exper-iments using three light treatments: Jungle light (imitating light in the jungle), D65 light (a standardized daylight illuminant) and control (commercial standard). Jungle light and D65 light included ultraviolet, while control light did not. During the home pen observations occurrences of behavior and social behavior were measured and compared between the three light treatments. No differences in behavior observed were significant, but there was a trend for more stretching behavior in D65 light. Age and time of day affected a couple of behaviors. In the preference tests hens were able to choose between two types of light during a three day period. A tendency for overall preference for the different light treatments was found. Laying hens preferred jungle over control light, and there was a trend for D65 over control light. There still seems to be a preference from laying hens for light spectra that imitate the light environment of their ancestors, including ultraviolet, compared to light conditions in modern poul-try housing.