Laying hens in caged confinement adapt well to artificial lights. However, concerns regarding illumination have emerged as producers switch from conventional cages to aviaries, enriched colonies, and free-range systems. Why is lighting crucial for chickens? How do you choose the appropriate illumination for each system, then? Dr. Ian Rubinoff, European account manager and technical services veterinarian at Hy-Line International, and Karen Schwean-Lardner, professor of animal and poultry science at the University of Saskatchewan, both have extensive knowledge in the field of poultry.
Why is lighting crucial for chickens?
Understanding the significance of lighting in the production of poultry requires an examination of the biological makeup of the birds. In people, light travels from the eyes to the brain. Light enters chickens' bodies via their eyes as well as their top of the skull, their pineal gland, and their pituitary gland near to their hypothalamus. Chickens have four varieties of cones, including red, blue, green, and an ultraviolet light cone, compared to human eyes' three types of cones, which are specialized photoreceptor cells that are responsible for how we perceive red, blue, and green light.
Similar to humans, chickens follow a regular cycle of day and night. Birds that have a regular cycle of day and night also have regular diurnal rhythms, or a schedule of normal daily activity. For processes like the generation of melatonin, this is crucial. According to Schwean-Lardner, "It is a regular cycle that is very crucial for birds because it governs things like immune function, development rate, and reproductive hormones." The health, immune system, mobility, and attentiveness of the birds are all improved by providing them with a day-and-night cycle.
She says, "Birds tend to be more active when they have a day-night cycle. They'll improve, which is totally counter to what was believed 10 years ago, which is pretty exciting.
Currently, Schwean-Lardner is studying the significance of the day-night cycle in birds. She is examining things like the appropriate starting age for lighting programs, the best method for implementing the change, and the effects of sudden vs gradual changes in lighting control on chickens. However, she is more interested in day-night cycles. In Schwean-perspective, Lardner's birds need darkness. "How much depends on a variety of factors."
Three parts of the spectrum—ultraviolet, visible, and infrared—each of which may have an impact on a bird's behavior—excite poultry biologists. On the electromagnetic spectrum, ultraviolet light is towards the short end. Visible light has a wavelength between 400 and 700 nanometers (nm). The wavelength of infrared light, which is more than 700 nm, is longer than that of visible light. Chickens have a vision range of 317–750 nm, while humans have a vision range of 400–750 nm. Furthermore, according to Rubinoff, hens can detect higher peaks at wavelengths of around 480 and 630 nm.
During a discussion at the Global Leadership Conference of the International Egg Commission in Bruges earlier this month, Rubinoff described how we may detect light in four distinct ways using a conventional LED spectrometer, a device that analyzes the intensity of light at various wavelengths. Correlated color temperature, or CCT, is what we have. It is measured in Kelvin (K). Rubinoff said, "This is a fantastic approximate indication for identifying whether a light is warm or chilly. "Under 3,000K indicates a warm light, whereas beyond 4,000K indicates a chilly light," says the author.
"This offers a general computation, but it doesn't give any clue as to the quality or composition of the light," he stated.
CRI, which stands for "color-rendering index," is a scale from 0% to 100% that indicates how well a certain light source renders color in comparison to a reference light source.
The standard unit for illuminance, or the quantity of light hitting a surface over a certain area, is the lux. Luxes are another way that light is measured. It's crucial to keep in mind that lux is gauged at a certain place in space, according to Rubinoff. "The light intensity I measure here is substantially different from what I measure down below. Your lux and light intensity may alter significantly with with a 10 cm adjustment.
He said, "This is something that is extremely hard for us, particularly as humans, to grasp.
The peak wavelength, which is the final measurement, simply indicates the prevailing color among all the wavelengths being produced from a certain light source.
How lighting is used in various settings
We can see up to 150,000 lux on an average bright day, so hens that have access to the outdoors are exposed to a very high degree of light intensity. When the sky is foggy, the red spectrum of sunshine is partially blocked, and the blue spectrum takes over. We see the reverse as the sun rises or sets. The red spectrum is expanding, whereas the blue spectrum is contracting.
According to Rubinoff, incandescent lighting resembles a little fire within a glass bowl more or less. For laying hens, incandescent lighting offers a decent spectrum. Sadly, they are highly inefficient, which is why manufacturers have begun switching to other light sources, beginning with fluorescent bulbs.
Fluorescent light has three peaks of light—red, green, and blue—and when they combine, they produce a lovely white light that humans can see. However, because of their better vision, chickens probably experience this differently and are able to distinguish the various color spectral ranges.
Full-spectrum light, like that seen in sunshine, is what we would refer to as an LED light. The peak wavelength of the blue spectrum of a typical LED bulb is roughly 440 nm. Each bulb has a unique distribution of light intensity over the remainder of the spectrum.
How to choose the appropriate bulb for your housing system
The objective of classic stacked deck or belted buildings, for both caged and colony, is equal light dispersion at all levels, according to Rubinoff. He said that this is often forgotten in housing.
Without taking into account the potential effects on the chicken, he stated, "In some homes, we installed lights every four meters and saw this enormous shift in light environment by cage or by colony. "I would encourage anyone who is thinking about installing a new caged facility or colony facility to try to go for a consistent lighting profile where you have either a bulb that evenly lights all the levels or you have a linear light that gives no gaps in light intensity between the different areas."
The productivity has undoubtedly increased significantly since we installed lights that extend all the way to the ground, he said.
In contrast, we need a less focused, wider light when there are just two or three cages.
Figuring out how to manage an aviary system or a free-range system has been one of the major obstacles in developing the ideal lighting conditions for the whole chicken sector. According to Rubinoff, putting LED lighting in aviary and free-range systems offers more uniformity than fluorescent illumination. The complete spectrum of an LED or incandescent is more compatible than the spikes of a fluorescent light, he said.
