The ultraviolet (UV) spectrum is a range of electromagnetic radiation that ranges from 100 to 400 nm. The light wavelengths within the UV light spectrum are shorter than the visible light spectrum (700-800nm) that can be seen by humans and poultry. The UV spectrum can be divided into 3 main categories:
- Ultraviolet A (UVA): 315-400 nm
- Ultraviolet B (UVB): 280-315 nm
- Ultraviolet C (UVC): 200-280 nm
UV light is naturally emitted from the sun, but what type of UV light reaches the Earth’s surface largely depends on the absorption and scattering of light wavelengths as they travel through the gases surrounding Earth. Almost all UVC light is blocked from reaching the surface by the stratospheric ozone layer, while a portion of UVB and UVA can reach Earth’s surface.
UVA light is not visible to the human eye; however, poultry have a specialized type of cone photoreceptor in their retinas that perceive light in this wavelength range (Wilkie et al., 1998; Yokoyama et al., 2000). Studies show that birds have faster resolution time under UVA light (Rubene et al., 2010) and have lower stress susceptibility and fear responses than birds reared without supplemental UVA light (House et al., 2020).
UVB is critical for vitamin D production in both humans and poultry. When skin is exposed to UVB wavelengths, a reaction occurs that synthesizes Vitamin D3 from 7-dehydroxycholesterol in the skin. UVB (or dietary vitamin D supplementation) is necessary to prevent rickets, minimize the incidence of tibial dyschondroplasia, and normalize growth in young birds (Lewis and Gous, 2009)
Although UVC does not reach the earth’s surface, artificially generated UVC technology is an effective tool for killing most bacteria and inactivating viruses and has become essential in the fight against biosecurity risks on poultry farms. UVC disinfection works by disrupting chemical bonds in DNA, RNA, and proteins, which are crucial for replication of bacteria and viruses. One application of UVC disinfection on poultry farms is the use of UVC germicidal cabinets for disinfecting fomites. These cabinets are fully enclosed, and objects are placed on a shelf while UVC light is irradiated from different directions onto the object. UVC cabinets are useful for reducing the risk of disease outbreaks due to the import of disease-contaminated objects.
References:
Wilkie, E. S., Vissers, P. M., Das, D., DeGrip, J. W., Bowmaker, K. J., & Hunt, M. D. (1998). The molecular basis for UV vision in birds: spectral characteristics, cDNA sequence and retinal localization of the UV-sensitive visual pigment of the budgerigar (Melopsittacus undulatus). Biochemical Journal, 330(1), 541-547.
Rubene, D., Håstad, O., Tauson, R., Wall, H., & Ödeen, A. (2010). The presence of UV wavelengths improves the temporal resolution of the avian visual system. Journal of Experimental Biology, 213(19), 3357-3363.
House, G. M., Sobotik, E. B., Nelson, J. R., & Archer, G. S. (2020). Effect of the addition of ultraviolet light on broiler growth, fear, and stress response. Journal of Applied Poultry Research, 29(2), 402-408.
Lewis, P. D., & Gous, R. M. (2009). Responses of poultry to ultraviolet radiation. World's poultry science journal, 65(3), 499-510.
