The effect of supplementary ultraviolet wavelengths on the performance of broiler chickens

Qualities of the light environment, such as the spectral composition of light, have been shown to impact growth and performance of broiler chickens. UVA light is visible to broiler chickens while UVB wavelengths promote endogenous vitamin D synthesis, which could support their rapid development. The aim of the current study was to investigate the impacts of supplementary UVA and UVB wavelengths on performance indicators of broiler chickens. Day-old Ross 308 chicks (n=638), reared to a target stocking density of 33kg/m2 , were randomly assigned to one of three lighting treatments: A) White Light Emitting Diode (LED) and supplementary UVA LED lighting (18-hour photoperiod); B) White LED with supplementary UVA and UVB fluorescent lighting providing 30 micro watts/cm2 UVB at bird level (lights on for 8 h of the total photoperiod to avoid over-exposure of UVB); C) White LED control group, representative of farm conditions (18-hour photoperiod). Mortality was recorded and broiler chickens were individually weighed at 8, 15, 22, 27 and 34 days of age. Generalised linear models and non-linear mixed effects models (Gompertz curve) were fitted to determine the effects of UV wavelengths on broiler mortality and growth performance. UV did not impact breast or leg weight of broiler chickens, but was associated with differences in mortality, growth and end weight. Broiler chickens provided with UVA for the full 18-hour photoperiod had slower initial growth than control broilers and a reduction in mortality. Results from male broilers reared with supplementary UVA + UVB for 8 hours indicated they could reach finishing weights sooner than controls, which supports the potential for UVA+B to improve the growth performance of males