Gradient lighting emerging in the U.S. poultry industry

Creating a gradient of lighting intensities inside a chicken house using natural or artificial lighting may be the way of the future for the integrated poultry industry.

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Inside house growing chickens for Perdue
Inside house growing chickens for Perdue
Research and experience show a stratified lighting environment, providing areas of high and low intensity light, is probably best for the birds. (Courtesy Perdue Foods)

Creating a gradient of lighting intensities inside a chicken house using natural or artificial lighting may be the way of the future for the integrated poultry industry.

In an exclusive interview with WATT PoultryUSA, leading animal welfare voices at Tyson Foods Inc. and Perdue Farms shared their changing philosophies and practices at their respective companies.

Tyson, ranked as the largest integrated poultry company by WATT PoultryUSA’s 2022 Top Broiler Companies rankings, and Perdue, ranked as the fifth largest, carry high public profile. They are concerned with today’s dual demands of consumers desiring transparency about their food supply and activists demanding change they see as beneficial for animal welfare.

Karen Christensen, the senior director of animal welfare at Tyson, and Dr. Bruce Stewart-Brown, Perdue’s senior vice president of technical services and innovation, said research and experience show a stratified lighting environment, providing areas of high and low intensity light, is probably best for the birds. However, they differ on the issue of natural light access.

High and low intensity

Christensen pointed to the on-going lighting research conducted at Tyson’s research farm in Arkansas which measured the animal’s preference for light intensity. The research clearly showed, she said, the birds want to eat under a bright light then rest and digest in a less intense area.

Chickens are derived from wild junglefowl occupying the low, prey niche in their environment. They want to hide from possible predators as much as possible.

In the research farm, lights as intense as 70 lux are placed directly above the feed line. Along the walls, far from the light source, it’s as dark as 3 lux. This range of light areas gives the birds a choice of lighting intensity.

A stratified lighting environment like this, she said, is arguably like the environment it might experience on the jungle floor. She argued this gradient lighting approach creates the best variety of intensity for the welfare and evolutionary preferences of the animal.

As research continues, she said Tyson is looking for a commercial lighting provider who can help them roll out this now-experimental lighting program in some locations over the next few years.


Stewart-Brown said about half of Perdue’s chicken houses use windows to providing natural light for the birds. He said this, like Christensen said, creates a stratified lighting environment with varying lighting intensities the birds can choose. This is a departure from previous notions of uniform, low intensity lighting.

Bruce Stewart BrownBruce Stewart-Brown, Perdue Farms (Courtesy Perdue Foods)


The poultry industry, he said, now recognizes the importance of lighting in poultry performance and behavior. In the past, the notion was a dark house discouraged unnecessary activity and kept the birds growing as efficiently as possible. Now, the realization is spreading that practice is not sustainable and the focus is shifting toward promoting natural behaviors.

Perdue started adding windows to houses in 2016 as part of its U.S. Department of Agriculture certified organic program. Stewart-Brown said Perdue realized the industry was evolving more toward the practices standard in organic production, so it expanded natural light access along with other enrichments.

The window and the sunlight introduced new management challenges, he said. Sometimes windows are covered to keep houses cool. Growers are careful of flocking in dark or bright areas and its consequences for litter moisture.

Farm Family Raising Perdue ChickensPerdue polled its farmers and they said they work longer in the house and enjoy working more in a house with windows. (Courtesy Perdue Foods)


Natural light

Sunlight permeating into the house may not be necessary for poultry growing. Research suggests modern LED technology can create similar lighting environments to nature using varying light intensity and color. LED is now the most common lighting source on commercial farms for economic and practical reasons.

Dr. Karen Schwean-Lardner, professor in the Department of Animal and Poultry Science at the University of Saskatchewan, said she does not think natural light is necessary. There is some welfare research suggesting birds engage with enrichments more when natural light access is added. However, LED’s ability to mimic nature or create an ideal light environment for the avian eye means natural light is not a necessity for modern poultry growing.

Stewart-Brown agreed natural light may not be necessary, but the animals and the farmers appreciate it. Perdue polled its farmers and they responded they will work longer in the house and enjoy working in a house more with windows than without.

In the same poll, the farmers said they believed the animals appreciated the sunlight, too. They said the light stimulates the birds and encouraged natural behaviors.

Tyson Research Farm (1)A range of light areas gives the birds a choice of lighting intensity to occupy. (Courtesy Tyson Foods)


Unlike Tyson, Perdue is a Global Animal Partnership chicken partner. This means some of its flock is certified by the non-profit animal welfare standards group to meet its expectations for housing, environment and slaughter of a broiler bird.  It raises birds rated as high as GAP 5.

According to Perdue’s 2022 Animal Care Report, GAP audited 174 Perdue farms and certified it for GAP 2, GAP 3 and GAP 5. GAP’s standards are tiered with progressive goals as the number increases.

At GAP 2, called enriched environment, birds must receive a minimum space allowance, two types of enrichments, six hours of darkness per day, natural light in the barn and a maximum of six hours of transportation time.

At GAP 4, called pasture raised, birds need daily access to pasture from four weeks of age, pasture maintained with a minimum of 50% vegetative cover, specialty breeds for outdoor production, outdoor shade and enrichments. GAP 5, called animal centered adds a need for continuous outdoor living on pasture maintained with a minimum of 75% vegetative cover by four weeks of age.

Other notable GAP partners include: Allen Harim Foods, Farmer’s Pride Inc., FreeBird Chicken, Jamaica Broilers Group Ltd., Miller Poultry, Shenandoah Valley Organic LLC and Wayne-Sanderson Farms.

Dark periods

Tyson and Perdue require periods of continuous darkness and other lighting standards.

Karen Schwean LardnerKaren Schwean-Lardner, University of Saskatchewan (Courtesy University of Saskatchewan)


Stewart-Brown said Perdue’s lighting plan recommends brighter lights for long periods of time when chicks arrive and then, seven days after migration, light intensity is lowered and six hours of darkness are required daily. Growers are asked to keep it bright enough to read a newspaper during light hours. For some specialty breeds, Stewart-Brown said, Perdue is evaluating if eight hours of darkness are necessary.

Tyson requires four-to-six-hour continuous dark periods. Christensen said the dark period establishes the circadian rhythm of birds, aiding in their immune and overall health.

In Canada, four hours of darkness for the majority of the production period are required by its national Codes of Practice for the majority of the grow period. Schwean-Lardner said strong scientific evidence shows birds physiologically suffer if they do not get at least four hours of darkness daily.

The science shows bird welfare, productivity and feed efficiency all increase by shifting to a longer dark period. Going from four hours to six or seven hours increases feed efficiency, reduces lameness, increases natural behavior expression and increases bird growth, as well as reduces mortality from metabolic and skeletal disorders.

Light color

Thanks to the proliferation of dimmer-enabled, color-switching and internet-connected LED devices, a broad range of light can be generated inside the poultry house.

The avian eye is different than the mammal eye. It posses an extra cone and perceives the visual world in ways farmers do not. Perdue and Tyson are researching different lighting colors inside the house for their effect on live production.

Current research at the integrator level is centered on the colors blue and green. These colors may be closest to the light filtering through the jungle canopy of their ancestors. The fourth cone, Christensen said, gives birds enhanced perception of the blue-green-purple color range.

Schwean-Lardner said on-farm research she’s familiar with have tried a combination of red or green, or a sequence of colors to see how birds react. One study conducted at Saskatchewan found birds see well at the blue end of the spectrum. Birds were less fearful and less stressed than under similar conditions with green and white light, but productivity was unaffected.

The role of lighting, enrichments and technology in welfare

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