The intensive production system for broiler chicken is characterised by the provision of a suitable micro-climatic condition such as temperature, airflow, relative humidity and light for proper bird's management which always, together with appropriate feeding and nutrition, favours the full growth and production potentials of the birds. Lighting, amongst other factors, is a potent and critical micro-climatic component in broiler houses as it influences many behavioural, physiological and metabolic processes in birds. To optimise the intensive system for broiler production, various lighting programmes (regarding light duration and its distribution, light colour/wavelength and light intensity) have been explored. This review compares the effects of different elements of lighting regimen on the growth performance, health, and welfare and carcass characteristics of broilers. Considering this, various degrees of intermittent photo-period (i.e. mixing photo- and scoto- periods within 24 hours) rather than one continuous photoperiod have been proven to significantly improve broilers’ weight gain by 3.4-5.8%, feed to gain ratio up to 7.3%, mobility up to 46.5%, decrease mortality rate ranging between 0.43% and 0.72%, and finally, increase carcass yield. Short wavelength lights and light intensity of ≥5 lux after the initial brooding period are said to stimulate birds’ metabolism and growth thereby, enhancing the production system. In conclusion, the lighting programme, apart from improving broiler productivity, could reduce cost expended on energy in an intensive production system.

Points that raise animal welfare concerns in the turkey broiler production chain are reviewed. Genetic selection of fast growing strains has increased locomotory problems and made natural mating impossible. A range of different photoperiods are used in practice (constant daylength, increased daylength with age, intermittent lighting) and have many consequences for welfare. High stocking densities have several drawbacks such as poor air quality, cannibalism and impairment of the gait of the birds. Methods of control against cannibalism, which include keeping birds at low light intensities or beak trimming, also raise welfare questions. Studies on the determination of optimal group size and on the possibility of enriching the pen environment are required. Depopulation procedures, transport and slaughter are further causes of poor animal welfare and would also benefit from further research.