Lighting programs for broiler chickens: Pre- and post-hatch effects on behavior, health, and productivity
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Lighting can have important effects on the welfare of poultry, but there have been few studies of the optimal photoperiods or light intensities for broiler chickens. Birds are sensitive to light stimulation even as embryos, so both pre- and post-hatch lighting regimes could have an impact. We conducted two experiments to examine lighting effects on broiler health and behavior. In the first, broiler eggs were incubated under either complete darkness (0L:24D), complete light (24L:0D), or 12 hours of light and 12 hours of darkness (12L:12D); chicks were then raised under a 12L: 12D photoperiod. In the second, chicks were raised under a 16L:8D photoperiod at one of three daytime illumination levels (dim to bright): 5 (typical commercial lighting), 50 or 200 lux. Treatment did not affect feed consumption, feed conversion, growth, mortality, or gait score. However, the eyes of both 0L:24D and 24L:0D broilers were significantly heavier at 5 lux. Activity rhythms were also affected: 24L:OD fed more during the 2 hours after the lights went on, and 5 lux were less active during the day. Broilers incubated under 0L.24D, or reared under 200 lux, were more fearful, as indicated by more intense wing flapping after being caught and inverted. In addition. 0L.24D broilers had more composite physical asymmetry, as assessed by differences in length and width of their toes and metatarsi, which is an indicator of developmental stress. These results demonstrate that providing light during incubation or brighter intensity light during rearing can have positive effects on broiler welfare without negatively affecting productivity.