A dairy cow barn ventilation system must offer fresh air all year, but in the summer it is critical. Fast-moving air where the cows are resting to provide proper cooling is essential. Whether or not the barn is ventilated naturally or mechanically using fans. Whatever approach, the design should allow for maximum airflow.

While 85% of Wisconsin's free-stall facilities are naturally ventilated, they may only sometimes have adequate cooling. Wind shadows cast by surrounding buildings, seasonal cornfields or other barriers, barn orientation, and other issues can all impair airflow.

Mechanical ventilation is by fans. There are several styles of barns. Naturally Ventilated barns have open side walls. Tunnel Ventilated barns have exhaust fans across the barn's width. Usually, the air flow is parallel to the feed lane. Cross ventilation is used in some barns, where exhaust fans run the barn's length and airflow is pulled across the feed aisle. Some designs incorporate natural and mechanical ventilation, with fans over the stalls and down the feed lane and ridge cupula fans or an open ridge to help remove hot, buoyant air from the barn.

Kevin says that while everyone talks about cow comfort, most discussions concentrate on free-stall size, etc., rather than on keeping the cows cool. His company focuses on keeping them cool economically. "People must recognize the critical significance of fans and dairy environmental controllers," he argues.

What you require will depend on the cow's lactation stage, whether she is dry, the climate, and the structure she is in. For many years, fans were seen as the least crucial part, but the industry is now more focused on why they are required.

Even a few years ago, people assumed that any fan would work without understanding fans' function and capabilities.

Many colleges have conducted good research illustrating the impact of heat stress on cow productivity and the benefits of proper ventilation and cooling cows. Surprisingly, there is still a belief that any air blowing over the cow is sufficient.

When putting a ventilation strategy together, look at the barn type, where the farm is located in terms of climate, and what the cow requires on the worst day of the year.

In most areas, the air should be moving at least five mph, which should be down where the cow is lying, not way up above her.

Cows typically lie down 12 times per day, and we want them to stay down as long as possible during those times. Always keeping the five mph within a yard of the cowbed.

"When ventilating an open pack, space the fans to create a wall of air traveling over the pack to ensure the cows are evenly cooled throughout. HVLS fans are ideal for this. This ensures that no moisture or pathogens accumulate.

We can enhance milk output by getting a cow to lie down for just one hour more daily. It also implies that she will eat more. If she lies down more, she is resting her feet (reducing the likelihood of lameness) and has a better repro since she is more comfortable.

We need to know why cows stand or bunch on a hot day. Is it due to the free stall condition or the cows trying to cool themselves?

A cow is akin to a furnace in that she generates a large amount of body heat. She accumulates heat at a rate of 1 degree per hour or higher when she lies down. There is less surface area to dissipate body heat. Therefore it takes her twice as long to dissipate the same heat when lying down.

Kevin says. "I installed temperature recorders in lactating cows and discovered that 120lb cows overheat at 63°, whereas 60lb production cows overheat at 75°. Increased production increases dry matter intake, which raises the heat load".

"It is crucial to comprehend all those aspects when putting together a ventilation strategy."

Every day is unique. As the days get shorter, larger HP motors with variable frequency drives allow the motor speed to be adjusted based on the Temperature-Humidity Index in the barn. "As the temperature drops, I don't have to run the fan as fast and use less electricity."

When the ambient temperature hits 70° F, the cow sheds a large portion of its heat through evaporative cooling.

Water is the most effective way to help a cow cool herself. This can be done by applying water straight to the cow's back. Wetting her at the feed bunk is the easiest. According to research, with air blowing in the feed lane and soaking every 5 minutes, you can rapidly cool her down because water improves her conductive heat exchange.

Cooling is essential in the milking parlor holding area. The high animal density exacerbates the heat, and the cows "heat up" faster. Without cooling, the cow's body temperature rises by 2°F  within 20 minutes of entering the holding area. We must use the same cooling principles, with an air speed of approximately 5 miles per hour and soaking. The goal is to keep heat-stressed cows out of the milking parlor.

It helps to indirectly chill the cows in dry climates by using high-pressure fogging in conjunction with high-velocity fans. Depending on the farmer's objectives, one or multiple stages of fogging can be installed.

 High-pressure fogging cools the air around the cow. Cooler air speeds up heat transport from the cow to the surroundings. One issue is that high-pressure fogging introduces additional moisture and heat into the atmosphere. It is critical to have fast-moving air to remove water from the building while keeping acceptable air quality."

The cow must constantly be the center of attention. "My interest is to develop a plan or solution that matches the farm and the environment. Then have the gratification of seeing the gains when we install these dairy ventilation controllers," Kevin adds.