The effects of color and intensity of light on behavior and leg disorders in broiler chickens.

Two experiments were conducted to investigate whether manipulating the wavelength and intensity of light could be used to increase activity and reduce locomotion disorders in meat chickens. The first experiment examined the effects of wavelength and intensity of light on bird activity. Male (n = 60) and female (n = 48) chicks were reared from Day 1 to 35 in red or blue light at three intensities. Walking, standing, drinking, aggression, and wing stretching increased with intensity in red but not blue light. In the second experiment, the effects of stimulating bird activity with bright red light in the early or late part of the rearing period on locomotion and leg disorders were examined. Male (n = 24) and female (n = 24) chicks were reared from Day 7 in either dim blue light to Day 55 (Treatment All Blue), or bright red light to Day 22, followed by dim blue light to Day 55 (Treatment Early Red), or dim blue light to Day 22, bright red light to Day 38, and dim blue light to Day 55 (Treatment Late Red). Bright red light considerably increased walking, feeding and stretching, particularly when applied early in the growth period. There were residual effects on activity after the birds had returned to dim blue light. Red light increased growth when provided at the beginning of the rearing period, but decreased it when provided later. Bone strength was reduced in treatment Late Red, which appeared to be related to the lower body weights of birds in this treatment. Bone length, weight, and torsion were not affected by treatment, but the tibia plateau angle was reduced by Early Red light in female birds. In Treatment All Blue, there was a high incidence of gait abnormalities, which was reduced by Early and Late Red light. It is concluded that rearing meat chickens in bright red light increases activity, which reduces locomotion disorders in the late rearing period. It is preferable to provide the stimulatory light early in the rearing period.