Properties of LED light can boost poultry production and profits
The demand for food worldwide is expected to double by 2030. To meet that demand, producers are adopting new technologies that will enable them to increase production at a reduced cost with less stress on the environment. Most of these production technologies focus on enhancing traditional inputs such as water, air, nutrients, and housing. One largely unexplored production input is light.
By utilizing LED lighting and taking advantage of the unique spectral requirements of poultry, swine, dairy cattle, fish, or crustaceans, farmers can reduce stress and mortality, regulate circadian rhythm, and substantially increase the production of eggs, meat, and other protein sources, while dramatically reducing energy use and other input costs.
As noted in a June 2013 LEDs Magazine article, niche applications enabled by solid-state lighting (SSL) include lighting specific to agriculture, and such applications could yield significant revenue potential. Major players in the SSL industry, such as Philips and Osram Sylvania, have developed spectrally-tuned LED lamps for farming and horticulture, in addition to smaller businesses such as Once Innovations, Luma Vue, and NextGen Illumination manufacturing LED lamps exclusively for the poultry market.
Many livestock farmers still utilize general-purpose residential and commercial 60W, 80W, and 100W incandescent lamps in their barns. These lamps are well suited to human environments, but incandescent light is not the same as sunlight, and the best light for humans is not necessarily the best light for animals. Animals have evolved living under the sunlight, whose spectrum differs substantially from that of incandescent light. Sunlight is a combination of all colors. Fig. 1a shows the amount of each color present in typical sunlight at noon. Note that the blues and greens are brighter than the reds at this time of the day. Fig. 1b shows the amount of color present in typical sunlight at the end of the day. Note that the reds are now brighter than the greens and the blues.
Modern barn lighting systems attempt to mimic the sun’s spectrum, which provides a continuous spectrum containing all colors with no gaps in between. Incandescent light effectively simulates sunlight at sunset, producing a continuous spectrum rich in reds with diminished greens and very little blue. However, this spectrum does not simulate midday sunlight, which is rich in blues and greens with diminished red. Some manufacturers try to put coatings on the bulbs to alter the spectrum, but this approach does not produce a continuous spectrum. Incandescent bulbs are also highly inefficient (producing more heat than light), burn out often, and require a fixture that is wet-location rated. All that will soon be moot, of course, as new production of incandescent lights is banned.
Compact fluorescent lamps (CFLs) have good efficiency and produce white light, but again, CFL light output is tailored to human vision. The white light is achieved by producing and combining narrow bands of red, green, and blue. As a result, there are large gaps in the spectrum between the red, blue, and green spikes, and many of the red, blue, and green wavelengths present in sunlight are lost. Blue light is exceptionally weak, and most of the deeper reds are lost. Overall, CFLs do a terrible job of mimicking natural sunlight. They are also hard to clean (because of their curly shape), contain small amounts of toxic mercury, require an enclosure to be wet rated, and do not dim well — plus their lifetime is shortened significantly when dimmed.
High-pressure sodium (HPS) bulbs offer excellent efficiency and high light output, with a color spectrum that is strongest in the reds and yellows, thus giving the bulbs their distinctive orange-yellow or amber hue. As with CFLs, however, much of the color spectrum is missing, especially the greens and blues. HPS lamps are also very difficult to dim, are slow to warm up, require a ballast for operation, have high upfront costs, and may contain sodium and/or mercury.
LEDs are the most efficient and environmentally friendly of the agricultural lighting options, producing white light by combining a blue LED with red and green phosphors. The spectrum is near continuous with especially strong blues, but also ample green and red. While not exactly daylight, the LED spectrum provides a close approximation of daylight from a human’s point of view, without the spectral gaps of other technologies. They also have the longest lifetime (up to 10 years with 24/7 operation), are highly rugged, are not susceptible to shock or vibration, and allow for color shifting and color control. LEDs have high upfront costs, but these costs are quickly recouped through energy savings, resulting in the lowest total cost of ownership for agricultural lighting options.