Summer ventilation recommendations

Ventilation is extremely important on the dairy farm, especially during the summer heat and humidity. In Part 3 of this four-part podcast series, UW-Extension and industry discuss tips and recommendations for keeping your facilities well ventilated during the summer.


Liz Binversie, UW-Extension Brown County Agriculture Educator


Mark Mayer, UW-Extension Green County Agriculture Agent
David Kammel, UW-Madison/UW-Extension  Biological Systems Engineering professor
Dr. Vicky Lauer, Professional Services Veterinarian, ANIMART


Time: 5:44 minutes


Liz Binversie: Greetings, I’m Liz Binversie, Agriculture Educator for UW-Extension in Brown county, Wisconsin. Today we will continue our discussion on heat stress and what producers can do now in the barn and out in the pasture to manage heat stress. On the panel today is David Kammel, Biological Systems Engineering Professor for UW-Madison and UW-Extension, Mark Mayer, agriculture agent for UW-Extension Green County, and Dr. Vicky Lauer, Professional services veterinarian for ANIMART.

Now, ventilation is very important to keep the herd healthy, but it’s even more important in the summer to keep air flowing through the barn. David, what are some cost effective ways to manage ventilation properly in the summer?

David Kammel: Well probably the first thing we have to think about is the different facilities these cows are in. We’ll start, potentially, with the holding area. That’s probably one of the places where we really need to focus on getting ventilation and air velocity over the cows when they’re packed tightly into that holding area. Normally, in a freestall barn they’ve probably got 100-120 square feet of space in that facility per cow. In a holding area, we’ve only got 15 square feet of space per cow so we’ve got a lot of heaters all tightly packed together in a tight space. It depends on the parlor of course if it’s got open side walls or curtain side walls or power ventilated, but that would be one of the first places that you really need to focus on adding fans, adding velocity, to help keep the cows cool when they’re packed very tightly together in the holding area. In the barns, we typically are dealing with naturally ventilated freestall barns, and housing facilities in Wisconsin. There are mechanical systems now coming into play on larger farms, but the majority of farms dealing with open curtain sidewall barns is just making sure the curtains are down earlier than maybe you think they need do. Mark mentioned in the earlier conversations of these podcasts that cows are very comfortable at 50-60 degrees, so it may seem kind of cool for us to have the windows open but for the cows they need the windows open. Then we can always supplement ventilation with velocity fans. I will say, one of the misconceptions of adding fans to a barn is that they don’t really ventilate the barn. In the naturally ventilated barn, the ventilation is occurring because of natural means. Wind is blowing or some thermal buoyancy is going on and we’re exchanging air from the inside to the outside. Velocity fans just mix the air or create a higher velocity of the air that’s in that space by the action of the fan, and they don’t really ventilate the barn, so we still have to think about ventilation first and add velocity next. Mark, do you have any other comments?

Mark Mayer: Yeah David, just to follow up on the holding area, it’s important to make sure that farmers design that holding area so that the cows are in there no longer than an hour maximum so even though you ventilate it, you want to make sure that you’re not having cows in there for a great deal of time in those tight quarters since it’s really difficult to lower a cow’s body temperature once it’s been increased. I also want to mention is that it’s really important to make sure that your fans and inlets are cleaned at least annually. Dirty fans will not run at their maximum capacity. In fact, their capacity can be reduced up to 40% by dirt that accumulates on the fan blades and screens, so make sure that those are cleaned on a regular basis, and finally I want to mention the use of natural ventilation. A lot of our farms use freestall barns, and about 95% of the time we have at least a 3 mile an hour breeze here in the state of Wisconsin. I encourage farmers to take advantage of that. For natural ventilation to work properly, make sure that you’ve got an open ridge with an opening of at least two inches for every 10 feet of barn width and that evenlets have at least half that opening in size. Sidewalls and eave height are important and should be 12 to 14 feet high. In my experience, the higher farmers get with that eave, the more natural airflow they get through the barn. This is even more critical in the wider 6 row freestall barns using natural ventilation. Don’t forget to take advantage of the natural winds that we have here that are free. Dr. Vicky, anything to add?

Dr. Vicky Lauer: Just a few things on calves. We can’t forget about them. For calves that are in calf barns, one really good way to cool them down is to use a summer positive pressure ventilation system. A lot of these barns have a winter system. You would need an actual, different summer ventilation system. This would really help cool the calves by drafting them. The same technology also works great in holding pens. I have some farms that are doing that and again you are going to cool those animals. It works pretty well, and then some of my farms unfortunately their heifers or older heifers are kept in 3-sided barns, and those barns just do not get much ventilation, so I recommend moving the tin on the backside of the barn to get more airflow.

Liz Binversie: Thank you again to our wonderful panel today. If you have questions or would like to reach any of our panelists, you can reach them by email, and tune in next time for Part 4: Cooling strategies.