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1008 PD: Swamp coolers for cows

Published on 30 June 2008

Swamp coolers are not as common in homes as they once were, but the same technology that cooled homes for decades can relieve your cows from the extreme heat of summer.

One producer in Minnesota tried it out in a new barn he designed for his calving and lame cows.



“The first time I asked one of the herdsmen up north about it I asked, “How is it in the summer with this cross-ventilated barn and evaporative cooling?” recalls Darrel Bruns, a producer in Renville, Minnesota. “He said he has to wear a sweatshirt some of the time. I said, ‘Ah, come on, it’s not that cold in there.’ He was pretty insistent that it works pretty well.”

With some experts and good-old ingenuity, Bruns was able to build a new special-needs barn on top of the existing cement flooring from an old barn. The crowning feature was the evaporative cooling system on the north side of the barn. He installed two 8-inch thick fiber pads that are 40 feet long and 6 feet high.

“You supply water to a reservoir, and it pumps water up and across the top of the pad. Then the water flows down the pad. Water goes over the surface area of that pad and as the air flows through it, like a radiator, a lot of it evaporates and cools the air down. It works much better when the air is dry, rather than when it’s humid. Hot and dry, it works beautiful. When it is 92 degrees outside, you can get it down to 70 if the air is dry.”

Bruns says during the first year after installation the hottest temperature in his barn was 780F. Most of the time, the temperature stayed around 740F. On dry days, he was able to drop the temperature to 690F. Add to the evaporative system the usual fans and misting for cow cooling, and Bruns says his cows are comfortable and cool.

Reasons for the installing the new cooling system
The first goal of the new barn was to give the close-up cows a comfortable place to calve. Bruns designed the barn so those cows are right next to the cooling unit on one side, while the calving area is on the other side. The calving area is also set up to be closed off and act as a comfortable vet room. Bruns is happy with the results he has seen so far.


“They got through the calving period better and quicker than they would have under the stressful conditions we get in the summer,” says Bruns, who started planning his new barn in February 2007. “So I think anything we can do to alleviate some of that helps. I think that’s important to get her up and going for her lactation. Anything that you can do to make it easier to get more milk in the end, and that’s really what we all want.”

The second goal Bruns had for his refurbished barn was to give lame or injured cows a place to recover. So on the back half of the barn, he has those cows in a quasi compost setup.

“We started out with loose housing, bedded with straw, and we didn’t like it so we went to sawdust,” Bruns says. “It wasn’t really built to hold 6 months’ to a years’ worth of manure, so we just clean it out every month and a half or so. It gets maybe 3 feet deep, then we take it out.”

Bruns has been able to keep some of his cows longer and more productive by using this method, which he believes makes his operation more profitable.

Lessons learned
Bruns was able to get the whole barn designed, constructed and in use within five months. He learned that having the right people helping you is important to getting a satisfactory result.

“Half the goal in these expansion projects is to have a barn that works,” says Bruns, who had professionals help him draw up the blueprints and build the new barn on the old barn’s concrete. “A lot of that seems simple, but until you draw it out and get it done properly you don’t realize the work that it takes. It is pretty important to get it done right.”


Bruns says if he does build another barn he would use the cooling system again but add some sprinklers over the headlocks. Due to the composting system they used, sprinklers were not advisable.

“The hot months of the year – June, July and August – take cows down so hard that we lose so much milk, and I don’t think they really ever recover,” Bruns says. “So if you can avoid that big drop in milk production, that’s key. [Cooling systems] kind of go like this, in order of effectiveness: Having nothing is the worst, having fans is better, fans and sprinklers is better yet. Then if you have evaporative cooling cells with sprinklers and fans, then that is the best you’re ever going to get ... aside from air conditioning, which will never happen.” PD

Ryan Curtis
Assistant Editor
Progressive Dairyman