Abstract
Simple SummaryLaying hens, like other poultry species, can perceive ultraviolet radiation; nevertheless, standard lighting in poultry houses does not contain UV-A light (UV). However, little is known about the impact of light quality (daylight spectrum by UV-A light illumination) on plumage loss, skin injuries and the production parameters of laying hens. Presuming that offering a daylight spectrum to hens could help to prevent the loss of feathers and skin damage caused by pecking, about 92,000 Lohmann Brown hens with untrimmed beaks were kept on a farm in different barns. In order to measure effects of a daylight spectrum, half of them were kept in poultry housing illuminated with UV-A light provided in addition to standard lighting. The other half was exposed to standard lighting for poultry houses. The results indicate that separately offered UV-A light alone cannot prevent damage to the hens’ integument caused by pecking. In general, complex interactions in conjunction with UV supplementation influenced the birds’ behavior. In order to promote animal health and welfare, further research is necessary to find out more about the appropriate level of UV supplementation and suitable light sources besides optimum light spectrum.Natural light with ultraviolet spectrum (UV) influences the birds´ perception, the reflectivity of their plumage and affects bird behavior. Therefore, in Germany, laying hens kept in barns should be provided with daylight inlets. Nevertheless, lighting in laying hen houses with a UV proportion is not common practice and little is known about the detailed effects of UV-A lighting during the entire rearing and production period. The present on-farm study examines the impact of light quality on plumage loss, skin injuries and production parameters of laying hens. Therefore, about 92,000 Lohmann Brown hens with untrimmed beaks were kept on a farm in two different groups. Half of them were housed in a barn containing 10 pens illuminated by additional UV-A light (simulate “daylight spectrum”). The other half in the second barn were equally grouped, but exposed to standard lighting for poultry houses. Health, production parameters and plumage condition were monitored during rearing and production. The study results reveal that additional UV-A light is associated with the occurrence of plumage damage and cannibalistic injuries during production. In all groups, the plumage condition of the hens was intact when the hens started laying and declined with age. Therefore, complex interactions alongside UV illumination, environmental enrichment, feed and feeding strategies as well as other management factors that possibly affected both feather damage and skin injuries must also be taken into account.
Highlights
Feather loss and skin damage deriving from feather and skin pecking is a serious welfare problem and may lead to higher mortality rates in laying hen husbandry
Gentle feather pecking does not lead to plumage damage, but severe feather pecking results in feather loss [2]
A light spectrum in the range of 400 to 700 nm plus a proportion of 4–5% ultraviolet light (UV-A light) in the range of 320 to 400 nm are recommended in laying hen husbandry [16]
Summary
Feather loss and skin damage deriving from feather and skin pecking is a serious welfare problem and may lead to higher mortality rates in laying hen husbandry. Gentle feather pecking does not lead to plumage damage, but severe feather pecking results in feather loss [2]. A main causative factor that has been found in several studies is the inhibition of foraging behaviors in pullets and laying hens [5,6,7,8,9]. It is known that the retinae of birds are sensitive to ultraviolet radiation [17] as well as blue, green and red light [18,19]. The lack of UV light may cause birds to perceive the plumage of other hens differently. Perhaps in the absence of UV light, plumage markings are not visible for conspecifics and might possibly promote feather and injurious pecking at conspecifics [20]
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