Assessment of The Role of Light in Welfare of Layers

Document Type : Review Article


Department of Veterinary Public Health, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt


Due to the difference in spectral sensitivity between poultry and human, there was an importance to identify the optimal light environment for the health, behavior, welfare, and production of layers. Overall birds have many types of retinal regional specializations, which have been interpreted with respect to both ecology and behavior. Light is one part of a complex of the physical phenomenon called electromagnetic radiation, which is depending on its wavelength. Light consists of 3 different aspects; intensity, photoperiod, and spectral content color. Photoperiod manipulation is likely the most important aspect of light in poultry production. Lighting programs in laying hen farms are depending on photoperiod, whereas, one hour increase in daylength leads to increase in 4 egg numbers. Overall, the use of either an increasing or intermittent lighting program will improve the welfare over those birds raised on constant light photoperiods. The light source may have an effect on leg disorders, with the use of fluorescent bulbs causing a lower incidence of the problem as compared to incandescent bulbs. Furthermore, the light intensity plays important role in poultry welfare, where the decrease in light intensities may cause lower body weights by altering behavioral patterns and can also cause eye damage, increased mortality, and a result in physiological changes in the birds. The different light colors had significant differences in all behaviors, plumage scores, foot condition, and growth performance of layers due to the presence of many types of retinal regional specializations. Thus, this article concludes that the source, spectra, intensity, and regime of light supplementation become major factors in modern poultry management.


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