How does cage-free ventilation change in cold weather?

Ventilation and management are key to providing birds with a living space that they can thrive in.

Meredith Johnson Headshot
Courtesy of Vencomatic Group
Courtesy of Vencomatic Group

Ventilation and management are key to providing birds with a living space that they can thrive in. “We have to remember we are providing an environment that balances feed costs, energy costs, and bird comfort,” explained Brett Ramirez, Ph.D., assistant professor in the Department of Agricultural and Biosystems Engineering at Iowa State University, during a recent interview.

Ammonia control and ventilation

“Typically, fresh air is provided through planned inlets that directs the air inside the house, allowing the cold and warm air to mix together and then be distributed throughout the house. This will dilute the concentration of noxious gases (like ammonia) in the room and help create a uniform environment,” explained Ramirez.

Additional approaches include using mixing fans to create a “racetrack” pattern or other airflow patterns to improve fresh air distribution, or some use ceiling mounted mixing fans that can blend fresh and warm air to be distributed throughout the room .

“Additionally, fresh air can be distributed through the manure duct, but it’s not commonly used. They tend to just use recirculated house air because its generally not advisable to bring cold air with hens are right above it, so that could make them uncomfortable,” advised Ramirez.

“In cage-free housing, stocking density or birds per cubic foot of air is different when compared to conventional housing, meaning there’s a need for better building insulation and heat in cage-free.”

Supplemental heat

As far as supplemental heat sources go, propane was the main concern. Keeping the barn tight to prevent leaks and getting air distribution correct becomes even more critical in cold weather areas. Further, temperature feedback sensor location and controller settings are important to reduce unnecessary heating costs.

“If propane prices are going up, it tends to make producers want to run their barns a little bit cooler, which is okay, or figure out how to dial back their ventilation. Most heat is lost through ventilation, about 70-80%. The tendency to conserve propane to reduce costs is there, but it’s not advisable because it leads to lower ventilation, and higher ammonia levels,” stated Ramirez.

Ramirez went on to explain that resisting the tendency to cut back on ventilation if propane prices start to climb is important. As energy costs increase, the relationship of balancing feed costs and room temperature becomes more important. If a producer is adding a lot of heat to a room, they need to make sure they’re distributing it properly, and keeping leaks to a minimum. “We can’t keep the houses warm with just chickens anymore, we have to learn how to manage heater settings and ventilation better,” Ramirez concluded.

Dust and ammonia in cage-free housing

While the cost of propane could be a concern to some producers, the trade off on bird health and air quality is important to consider. The producer’s goal is to reduce dust and ammonia levels to prevent harm to the workers and the birds. 

According to Dr. Hongwei Xin, director of the Egg Industry Center, increased bird activity in cage-free farming has led to increased levels of airborne dust. Additionally, ammonia levels are of concern due to uncontrolled manure areas and a lack of ventilation to preserve bird warmth. 

Xin explained that changing a bird’s diet can affect the amount of ammonia present in the house. Some suggestions he made from other studies include reducing dietary protein, adding dietary fibers (such as wheat middling and soy hull) and adding supplements (such as distiller’s dried grains). 

 

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