Light Climate in Poultry Production: A Forgotten Aspect?

Running a farm involves feed, chicks or pullets, equipment, ventilation, and more. But when people talk about "climate," they usually mean temperature, air, or humidity -lighting tends to get overlooked; while light is an essential part of the overall farm climate.

Why does a poultry house need light at all? Ideally, to mimic sunlight: simulating sunrise and sunset, stimulating natural behavior and biorhythm, activating the birds, structuring their daily routine, and cueing rest periods.

What light actually is

Light is the visible slice of the electromagnetic spectrum - the part we see in color. Sunlight spans from ultraviolet to infrared, and the visible band within that is much narrower, with each color corresponding to a specific wavelength (measured in nanometers). Together, these wavelengths combine into white light, which is polychromatic and is what we perceive as sunlight.

Humans see a narrower slice of the spectrum than birds do. How much of it a species can see depends on its own biology - the eye's structure, and the placement and number of rods and cones. That structure determines which color combinations and light intensities an animal can pick up.

Birds are more light-sensitive than we are and register changes in light more easily. They also have a kind of third eye - the pineal gland - which senses light directly through the skull, across a range from ultraviolet to infrared. Longer wavelengths - yellows, oranges, reds - penetrate the skull more easily, and that's the same spectrum found in warm white light.

"That's why we at HATO recommend warm white for layers or breeders. The red part of the spectrum more readily stimulates laying, hatchability, and production."

Because birds' spectral sensitivity is so much wider than ours, farms need natural light backed up by artificial lighting to properly support their vision. In fully enclosed houses, birds need a broad white-light spectrum to see well.

With LED fixtures - the standard technology on farms today - birds can even access ultraviolet light, improving their vision further. That means calmer birds and better performance overall, especially in layer breeder flocks and broilers.

Cool white light is recommended during rearing because of its blue and green content, which activates the bird and strengthens bone structure and muscles. But without careful management, it can also trigger unwanted behavior - aggression, feather pecking, or crowding - all of which push mortality up.

The bird must be at the center of every farm management decision, including the choice of lighting in the house. But there's no one-size-fits-all solution across every type of housing or application.

"The standard bulbs you'd pick up at a hardware store simply aren't built for what birds, or poultry houses, actually need," says Cristabel Huerta.

Lighting shouldn't be treated as a cost; it's an investment.

• Lighting is a core part of building a climate that's comfortable and works in harmony with the birds and their environment. Light sets the day/night cycle and, with it, activity and rest periods and production cycles - all of which matter for regulating hormones, biorhythm, immunity, and feeding habits, and which support natural behavior.

• Lighting programs manage the photoperiod and light intensity according to the bird’s life stage, genetics, location and type of housing. During the starter phase, long light hours are essential - they help the birds see well, adjust to their new surroundings, find water and feed, recognize other birds, and gain comfort, confidence, and mobility.
  

• As the birds grow, light hours are reduced, though research shows birds still need long photoperiods for welfare-related behaviors like eating, sleeping, playing, preening, and dust bathing.

• The recommended dark period is 3 to 4 hours at least. Some production cycles use intermittent lighting, depending on management practices. Either way, lighting needs to be uniform - reaching the right areas with the right intensity and following whatever program the genetic line requires.

• Light needs to reach the correct zones so birds can read their environment, get to feed, and experience even distribution throughout the house — avoiding overly bright or overly dark spots that trigger unwanted behavior.

Building a lighting plan

Getting the light climate right means building a lighting plan tailored specifically to the birds' needs and the type of housing.

Just as with lighting programs, no single bulb works for every housing type. The right fixture is whichever gives the best light diffusion for the situation - sometimes a wide beam at lower intensity, sometimes a narrower, more intense one.

It all comes down to where stimulation needs to happen and the type of housing, closed, semi-closed, or open, plus factors like whether it's just supplemental lighting, or where the nests are positioned. Areas where more bird activity is wanted need more light.

If the goal is getting birds to use the nests, darker zones around them with even light distribution are needed so eggs get laid in the nest rather than on the floor. In cage housing, light needs to reach the feeders, without so much brightness that discomfort the birds.

In cage traditional houses, it's common to see uneven lighting between levels - the top tier ends up too bright, leading to pecking, while the bottom tier barely gets any light at all, decreasing uniform performances.

Fixtures for farm use need to hold up in harsh conditions, humidity, ammonia, dust, and should be waterproof, sealed for washing, and built to cut fire and biosecurity risks.

Light as a management tool

Lighting is genuinely a tool that can be used to manage desired bird behavior on the farm. Any change in housing should keep a similar light climate across both rearing and production.

In egg production, it's important to always keep the red spectrum present, and warm white light helps keep the birds calmer overall.

For certain interventions, like catching broilers, a change in colour lighting makes the job easier.

"Adding monochromatic blue to the main lighting, with the option to switch from white to blue during catching, cuts operational costs and increases productivity." says Cristabel. "Less stress means fewer broken wings, fewer breast bruises, better meat quality and less downtime."

 As conclusion, an optimal light climate is a light climate that fulfills the needs of the animal and the farmer, helping create better welfare and better production results.