Don Bennink is one of the most innovative producers around, so when he tries something new, other people perk up their ears.


photo courtesy of jake martin

Within the past five years, he has put in four tunnel-ventilated barns — two of them retrofits of existing free-stall barns and the other two brand new. He completed the first retrofit in 2001 because he wasn’t satisfied with the existing natural-ventilation systems for cooling cows. “I just didn’t think they were doing the job,” he says. “I wanted more (cow) comfort through the summer.”

So far, Bennink is pleased with the way the tunnel-ventilated barns have performed in the Florida heat and humidity. “We feel cows are more comfortable in this system than in a naturally ventilated barn,” he says.

As more and more data are obtained on the performance of tunnel-ventilated barns, more and more producers may follow suit. The data on the barns look good so far.

Requires extra management
This is not to suggest that the tunnel-ventilated barns are ideal by any means. There are challenges, and the barns require a high level of management for success, says Jake Martin, consulting agricultural engineer in Gainesville, Fla. 

In the Southeast, the high humidity presents a challenge. Tunnel-ventilated barns with evaporative-cooling systems lose much of their efficiency when the humidity gets above 90 percent. Therefore, it becomes a matter of balancing ambient air conditions outside the barn with those inside.

Other management issues include handling extra automation, having backup ventilation systems in place, keeping fans clean, maintaining negative-pressure conditions inside the barns, and directing the air where it does the most good.

The type of tunnel-ventilated barns suited for a southern climate cost about 25 percent more than the standard naturally ventilated barns, Martin says. That can raise the cost from $1,200 per cow, on average, to $1,500. Extra items include exhaust fans, insulation in the ceiling, end-wall construction, curtains for the sidewalls, high-pressure cooling (foggers or misters) and other items.

Helps controls environment
Todd Tuls, owner of Double Dutch Dairy in Shelby, Neb., put in three tunnel-ventilated free-stall barns five years ago and liked them enough that he built three more.

“In wintertime, you can keep the barns warmer and in the summer, you don’t have the heavy fly pressure compared to conventional naturally ventilated barns, and you can control your environment a little better (regarding air direction and wind speed),” Tuls says.

For years, Shenandoah Dairy in Live Oak, Fla., raised cows under dry-lot conditions. Then, in 2003, it made the leap to tunnel-ventilated free-stall barns without first trying naturally ventilated barns along the way.   


This tunnel barn at North Florida Holsteins has fans on one end pulling air through the building. The other end of the barn is wide open, with no end wall in place. (photo courtesy of jake martin)

The primary reason for going with two tunnel barns (with 600 cows per barn) was the configuration of the farm, says Ed Henderson, co-owner of Shenandoah Dairy. The tunnel barns could be built close together and perpendicular to the milking parlor, which cut walking distance for the cows.

Yet, there is a definite cow-cooling benefit, Henderson acknowledges. The temperature inside the tunnel barns can be as much as 15 degrees cooler than the outdoor temperature, provided the humidity isn’t too high. On really humid days, there may only be a five- to six-degree difference. 

Since Henderson has never worked with any other kind of free-stall barn, it is difficult for him to say that the cooling difference has resulted in “x” more pounds of milk from his cows. Production has definitely gone up since the dry-lot days, but it has coincided with a number of other management changes besides the switch to tunnel-ventilated free-stalls. 

“I’m happy with what I’ve done. But can I say I am milking more with a tunnel-ventilated barn? I don’t know,” Henderson says. “I have way more questions than I have answers here.”

Reduces heat stress
Martin, who helped design the tunnel barns for both Henderson and Bennink, says tunnel-ventilated barns may become more common in the future if the data from existing barns continue to look favorable. 

“However, I don’t think they will ever completely take the place of a well-designed ‘standard’ free-stall barn since many producers are either unwilling or unable to accept the challenge of the additional management requirements,” he adds.

Terry Smith, assistant professor in the animal and dairy sciences department at MississippiStateUniversity, agrees that tunnel barns have something to offer. He says the cooling capabilities of tunnel-ventilated barns look very favorable to conventional systems, based on research that he and others have done.

“I think they provide superior cooling, and because of that they allow producers to maintain production — and income — during hot weather,” Smith says.  

In an experiment three years ago, MississippiState researchers found that cows cooled by tunnel ventilation ate 4 pounds more feed per cow per day and produced 5.9 pounds more milk per cow per day in the summertime heat than cows cooled with shades and fans alone. The tunnel-ventilated cows also had lower peak body temperatures and slower respiration rates.


A high-pressure cooling system with misters creates a fog-like effect in this tunnel barn at Shenandoah Dairy in Live Oak, Fla. (photo courtesy of jake martin)

The tunnel-ventilated barn at MississippiState was equipped with cooling cells. Often, the producers in the South have found that they need some form of supplemental cooling besides the simple act of moving air over the cows.

Bennink, who runs the 3,100-cow North Florida Holsteins facility in Bell, Fla., uses a high-pressure cooling system (involving misters) to supplement the fans. When the misters are on, the air in the barns can take on a fog-like quality. It’s very effective in cooling cows.

“We can take a 95-degree day and bring it down to just under 80 (in the tunnel-ventilated barn),” Bennink says.

Some people might scoff at the idea of using misters in a humid area like north central Florida. But Bennink did his homework. He consulted with Dennis Armstrong, a nationally known dairy-facilities specialist, on the concept, since Armstrong had worked with these types of barns in Thailand. Armstrong confirmed that if these barns will work in a country like Thailand, which is even more humid than north Florida, they will work here as well.

In other parts of the country, such as the New York, it may be sufficient to simply run fans without supplemental evaporative cooling.

Has a place, even in the Northeast
Heat stress can occur even in New York. In fact, Normand St-Pierre, dairy scientist at OhioStateUniversity, has calculated that dairy producers in New York and Pennsylvania lose about $50 million a year due to heat-stress-related causes.

Researchers at CornellUniversity in New York have reported favorable results with tunnel-ventilated barns that simply rely on fans to move air (without supplemental high-pressure cooling systems). During the summer of 2000, researchers found the air temperature in tunnel-ventilated barns in New York and Ohio were 0.72 degrees F cooler, on average, than the naturally ventilated barns during the warmer times of the day.

Curt Gooch, dairy housing environmental engineer with ProDairy/Cornell University, agrees the tunnel barns can do a good job when it comes to ventilating a barn and relieving heat stress. At many sites, they provide more predictable and more reliable air exchange in the summertime than  naturally ventilated barns, he adds.

Gooch says he thinks tunnel-ventilated barns will become more common as producers learn the potential benefits.

May provide a payback
Systems vary considerably, so it can be misleading to compare research findings on the potential paybacks. An economic analysis done by Cornell researchers in 2000 indicates that the type of tunnel-ventilated barns suitable for the Northeast often can pay for themselves by boosting milk production by 2 pounds to 5 pounds per cow per day. And, in the Southeast, if the tunnel barns cost 25 percent more than conventional barns, a producer will need to boost his milk production accordingly.

While the economics are still not well defined, producers who have installed tunnel-ventilated barns seem to like them enough that they end up building even more.