In poultry farming, artificial lighting is a tool which can, when applied properly, greatly enhance performance and therefore profitability. An artificial lighting system in a barn has three characteristics--color of the light (wavelength), intensity of the light, and the amount of time the lights are on each day (daily photoperiod). With the development of LED technologies, farmers can now simultaneously vary the color, intensity and photoperiod of the lighting in animal houses and barns. This is important because many scientific studies have demonstrated that simultaneous management of these three components can greatly improve poultry production. Traditionally, the artificial lighting in a barn has been limited to incandescent, fluorescent or highpressure sodium lamps. These lamps have fixed intensity and fixed color; therefore, once installed the only controllable variable is the length of daily light exposure (photoperiod). With LEDs, two more characteristics of the lighting can be manipulated, thus giving new tools for farmers to increase productivity and improve animal welfare. Indeed, it has been reported that skillful application of LED lighting systems can increase net profit by 20-30% (Rozenboim et al., 2005).