How does barn lighting affect turkeys?

Monday, September 22, 2025

Dr. Karen Schwean-Lardner’s Lab Has Been Investigating Wavelength, Flicker & Day Length

By Emily Mckinlay

Lighting in turkey barns has the potential to affect a flock’s productivity and welfare. Dr. Karen Schwean-Lardner, a professor in the Department of Animal and Poultry Science at the University of Saskatchewan, has been investigating these impacts and how they relate specifically to turkey producers.

“I would caution turkey producers to not just base their lighting decisions off traditional broiler barns because we are seeing some different responses in turkeys,” says Schwean-Lardner.

Many turkey producers have already transitioned to using LED bulbs in their barns to improve efficiency.

“LED lights last for a long period of time and are cheaper to run than incandescent lights,” says Schwean-Lardner.

“This can come with the ability to change features like wavelength.”

When making lighting choices for their barns, it’s important for producers to understand the potential implications of these decisions on their birds.

What makes up barn lighting?

Lighting choices can impact any type of livestock kept in a barn. There are three major characteristics of lighting, explains Schwean-Lardner.

“The first aspect is the duration of lighting,” she says.

“There are the number of hours the lights are on, which is called the photoperiod, and the number of hours of darkness, called the scotoperiod. This also includes how the light is distributed – it may flicker or come in short pulses.”

The second feature is wavelength.

“Different colours of light have different wavelengths,” says Schwean-Lardner.

“With more use of LED lights, there is an interest in different wavelengths and their effect on turkeys.”

Light intensity, or the brightness or dimness of the lights, is the final factor that should be considered in barn lighting.

Producers should also pay attention to how the light is distributed. Patches of light or uneven distribution, often a challenge with windows, can affect how the turkeys move around the barn.

Schwean-Lardner says that despite the many different types of barns and their varying approaches to lighting, these factors can all have an impact on turkey growth, health, and welfare.

Lighting and turkey performance

The characteristics of light can affect turkeys in different ways. Many of these effects are behavioural, but these changes will also influence bird performance.

Day length has been used in poultry barns to influence bird performance and activity levels. Schwean-Lardner explains that lighting duration is critical for diurnal function in turkeys.

“Light duration is so important because it drives health and welfare. Birds need to have a distinct day period and a night period. The light has to be light enough to be day, and dark has to be dark enough to be night,” she says.

“Diurnal functions influence health, mortality, growth rate, and behaviour. Turkeys need a minimum of four hours of dark every day. In our research, we tend to use six to seven hours of dark instead because of the better health and welfare levels we’ve observed.”

She adds that a day-night cycle is important for melatonin production and sleep.

“It’s a bit complicated, but it’s amazing the difference that light duration can have for birds.

“You need a day-night cycle with a night period to achieve quality sleep. Melatonin production is driven by day-night cycles, and if birds don’t have that, then melatonin is not produced properly. It’s so important to have this dark time.”

Previous studies from Schwean-Lardner suggest that disruptions to sleep and melatonin production can also impact feeding behaviour in turkeys. Other research found that young turkey toms exposed to 23 hours of light developed sight problems.

“In a study on turkey lighting programs, 16-week-old toms were raised on a 23-hour light period, which was the norm up until approximately 10 years ago.

“We found cataracts in those birds, and it caused weird growth patterns on their eyes. Giving turkeys an adequate dark period is critical.”

Light intensity – brightness or dimness – also influences bird behaviour.

“Light intensity in turkey barns affects activity level,” says Schwean-Lardner.

“In brighter lights, birds tend to be more active. If you are having problems in your flock, especially with cannibalism, lights can be dimmed a little to try to lower activity.”

She does caution that birds are visual, and that if the lights are too dim, it will be difficult for birds to see to eat, drink, and move around their barn.

Schwean-Lardner’s lab has recently turned its attention to investigating the effects of flicker and wavelength on turkey welfare and performance.

“We finished a study last year looking at light flicker. We wanted to know what happens to turkeys when lights flicker in the barn. It’s not uncommon,” explains Schwean-Lardner, who also notes that their findings suggest that lighting affects birds of different ages in different ways.

“We found that young poults tried to hide. They did not like the flicker and did not eat and drink as much when the lights were on. We see a bigger impact of light flicker on turkeys earlier in life than later in life.”

As LED lights present more opportunity to change light colour – therefore changing wavelength – Schwean-Lardner’s lab is working on wrapping up studies investigating how this would affect turkeys.

“Light wavelength is interesting because we don’t know a lot yet.

“Just recently, we finished a trial studying light wavelength, but we are not ready to talk about results yet. There’s not a lot of other research published about it, but we will know more about it in the near future.”

This study had three rooms of turkeys housed under white lighting, three rooms of turkeys in blue lighting, and three rooms of turkeys in green lighting at the University of Saskatchewan research facilities. Schwean-Lardner and her team are in the process of analyzing their results.

Behind the research

Schwean-Lardner has been passionate about poultry research for her whole career. Turkeys are not her only focus. She also works with broilers and Leghorn poults.

She initially started in this field at USask to work with her mentor, Dr. Hank Classen.

“He did barn lighting research long before I was ever here.”

Her work started with her PhD studying the impact of day length on broiler production. In this, it was solidified how important lighting is for welfare and production.

“My love for how much impact light can have on birds has kept me studying in this area.”

She also notes that the facilities at USask play a large role in the quality of lighting research she is able to complete.

“When we think about light research, some research barns have one large room with multiple pens in that room, and that can’t work for lighting work.

“In our facility, we have nine individual rooms, and in each individual room, we have control over the lighting. It’s like having nine miniature barns. The rooms are big enough to have a high number of birds. We had 300 turkeys in a room for our last study.”

This allows her lab to have individual control over the light each group receives, while also maintaining a large enough sample size.

Looking forward, Schwean-Lardner and her team are excited about continuing their work on the effects of light wavelength on turkey performance and welfare. And they say they are in the process of securing funding for additional projects.

“We have tons of ideas, so we’ll see what comes out of that.” BF