The effect of supplementary ultraviolet wavelengths on broiler chicken welfare indicators
Charlotte Jamesa,⁎, Lucy Asherb, Katherine Herbornb, Julian Wisemana
Qualities of the light environment are important for good welfare in a number of species. In chickens, UVA light is visible and may facilitate flock interactions. UVB wavelengths promote endogenous vitamin D synthesis, which could support the rapid skeletal development of broiler chickens. The aim of the study was to investigate the impacts of Ultraviolet wavelengths (UV) on welfare indicators in broiler chickens. Day-old Ross 308 birds reared under commercially representative conditions 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 (on for 8 h of the total photoperiod to avoid over-exposure of UVB); C) White LED controlgroup, representative of farm conditions (18-hour photoperiod). Welfare indicators measured were; feather condition (day 24, n=546), tonic immobility duration (day 29, n=302), and gait quality, using the Bristol Gait Score (day 31, n=293). Feather condition was improved in male broilers in the UVA treatment (A), compared to the control treatment (C). Birds in the UVA treatment had shorter tonic immobility durations compared to the control treatment (C), suggesting lower fearfulness. Broilers reared in UVA (A) and UVA+UVB (B) had better Bristol Gait Scores compared to the control (C). Together these results suggest UV may be beneficial for broiler chicken welfare. While treatment A and B both provided UVA, the improvements in welfare indicators were not consistent, which may be due to exposure timedependent beneficial effects of UVA. The modification of commercial lighting regimes to incorporate UVA wavelengths for indoor-reared broiler chickens would be an achievable change with significant positive impacts on bird welfare.
The provision of UV wavelengths, particularly UVA, has potential to improve the welfare of indoor reared broiler chickens. Lighting environments designed with the avian visual system inmind may improve the quality of visual feedback and reduce fearfulness. Future research identifying the links between UVA exposure and positive impacts on feathering rate, stress, activity levels and flock interactions would be of further importance to broiler welfare.
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