Application of Ultraviolet Light for Poultry Production: A Review of Impacts on Behavior, Physiology, and Production

Abstract

The application of ultraviolet (UV) light in poultry production is garnering increased interest with the drive toward improved poultry welfare and optimized production. Poultry can see in the UV spectrum (UVA wavelengths: 320–400 nm) thus inclusion of these shorter wavelengths may be viewed as more natural but are typically excluded in conventional artificial lights. Furthermore, UVB wavelengths (280–315) have physiological impact through stimulation of vitamin D pathways that can then improve skeletal health. However, better understanding of the effects of UV supplementation must occur before implementation practically. This non-systematic literature review aimed to summarize the impacts of UV supplementation on the behavior, welfare, and production of laying hens, meat chickens (breeders and growers), and other domestic poultry species including directions for future research. The literature demonstrated that UVA light has positive impacts on reducing fear and stress responses but in some research, it significantly increases feather pecking over age during the production phase. UVB light will significantly improve skeletal health, but an optimum duration of exposure is necessary to get this benefit. Supplementation with UVB light may have more distinct impacts on egg production and eggshell quality when hens are experiencing a dietary vitamin D3 deficiency, or if they are at the terminal end of production. The relative benefits of UVB supplementation across different ages needs to be further verified along with commercial trials to confirm beneficial or detrimental impacts of adding UVA wavelengths. Further research is warranted to determine whether adding natural light wavelengths to indoor poultry production is indeed a positive step toward optimizing commercial housing systems.

Commercial Free-Range Laying Hens’ Preferences for Shelters with Different Sunlight Filtering Percentages

“…The sunlight spectrum contains all forms of ultraviolet (UV) radiation: UVA (315-400 nm), UVB (280-315 nm), and UVC (100-280 nm), of which only UVA and UVB reach the earth's surface. Hens can visually perceive UVA and UVB has a physiological effect on the synthesis of vitamin D3 in featherless skin [31]. However, high intensities and/or overexposure of UV radiation may have damaging effects [32,33], and, thus, hens might avoid direct sunlight at its most intense.…”

Relationship between sunlight and range use of commercial free-range hens in Australia

“…Correspondingly, during the hen counts in this study, more birds were observed outside on cloudy days, similar to an observation reported by Whay et al [ 44 ] during visits to 25 commercial free-range farms in the UK where they noticed that maximum use of the range happened on calm, cloudy days. UV supplementation in indoor settings can improve hens’ behavioural repertoire and skeletal heath [ 7 ] and hens will show preferences for low levels of UV AB light compared to UV deficient environments [ 33 , 52 ]. This may support the birds’ greater use of the ‘sun’ range area in the morning and late afternoon, but when the radiation is at its peak irradiance, hens avoid this, similar to hens exhibiting preferences for shelters that block more UV radiation [ 34 – 36 ].…”

“…Free-range hens get exposure to sunlight for at least part of the day with access to move freely in an outdoor area rather than continuous indoor housing. The outdoor exposure provides hens the opportunity to access natural vitamins from herbage, and vitamin D 3 from ultraviolet (UV) radiation in sunlight [ 5 – 7 ] in addition to what is provided in their formulated feed. Ranging outside may also reduce feather pecking behaviour to improve plumage coverage and encourage greater expression of natural behaviours such as foraging, walking, and dust bathing [ 8 ].…”

“…In experimental choice trials, hens show preferences for a lower level of UV exposure and will exhibit different behavioural profiles under full spectrum (includes UVA or both UVA and UVB) versus control lighting [ 32 , 33 ]. Hens may be motivated to access some UV exposure for the health benefits through stimulation of the vitamin D 3 pathways [ 7 ] but high intensities of UV radiation could result in skin damage [ 28 , 29 ]. On Australian commercial farms, observations of hen ranging behavioural patterns have documented lower range use across the midday/early afternoon period when the sun is most intense and during the summer months [ 34 , 35 ].…”

Effect of Ultraviolet Radiation on Reducing Airborne Escherichia coli Carried by Poultry Litter Particles

“…A periodic cleaning schedule is suggested when applying the system in poultry houses. Next, even though UVA (wavelength of 315–400 nm) was well studied and proven that it had positive effects on poultry [ 27 ], UVC (wavelength of 200–300 nm) was not well studied yet. Therefore, the application of UVC, in this case, 254 nm, into the poultry environment also needs to consider its impact on the poultry.…”