Light as exogenous factor can control metabolic disorders and impact embryonic development in broiler chickens - a review.

Continuous genetic selection and improvement in nutrition have led to a fast growth rate of modern strains of broiler chickens. Metabolic disorders such as ascites, sudden death syndrome and leg problems are associated with a rapid early growth rate in broilers whereas their incidence can be decreased by slowing down early growth rate. It is known that by changing lighting programs, either by reducing duration of light (restricted photoperiod) per day or imposing intermittent lighting schedules, feed utilisation of broiler chickens will be improved and the incidence of metabolic disorders will be lowered. The aim of this article is to review new findings about the effects of different lighting programs on these problems in broiler chickens. Additionally, light stimulation during embryogenesis is a critical element in avian development and well-being. Many researchers have focused on manipulation of different light regimes during incubation to optimise hatchability and early post-hatch growth as well as to improve the chick's adaptive response to the environment through epigenetic mechanisms. Therefore, goal-oriented embryonic light stimulation may be a viable option for reducing the hatching window and improving hatching performance, behaviour and welfare of broiler chickens. [ABSTRACT FROM AUTHOR]