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Keeping calf barns cool

Courtney Halbach, Rebecca Brotzman and Ken Nordlund for Progressive Dairyman Published on 31 March 2016

Keeping calf barns well ventilated during warm weather starts with the design of the facility.

The Dairyland Initiative’s preferred nursery calf barn design is a one- or two-row individual calf pen building utilizing natural ventilation.

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Orientation of the barn east to west will avoid direct afternoon sun exposure in the barn and on the roof, and allow for better capture of prevailing winds.

Tall 12- to 14-foot curtain sidewalls with a very short 18- to 24-inch concrete base wall and an open ridge will freely allow wind to both deliver fresh air and exhaust stale hot air from the building. The sidewall should be fitted with retractable curtains, preferably split to allow finer control of wind entry during cooler weather.

Inside the barn, pens need to be constructed to allow wind to work its way into the calves’ immediate environment. A very open design to the front and rear panel on individual calf pens allows greater opportunity for breezes to move through the pens.

In group-fed nurseries, be sure to locate feeding rooms away from the prevailing wind side of the barn (south sidewall in much of North America) to avoid creating a wind block.

If an existing barn has a tall, typically 4-foot concrete sidewall below the curtain, ventilation might be improved by mounting a “baffle board” on the sidewalls to deflect winds downward into the pens.

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The baffle board can be as simple as a wide plank of 8 to 10 inches hinged to support posts, positioned just above the concrete sidewalls and held on a downward angle using cables from the board to the rafters (Photo 1).

Baffle board on a 4-foot concrete sidewall to deflect wind downward into the calf pens

Increasing awareness of potential heat stress in calves has resulted in producers installing recirculation fans in calf barns. Such fans, however, will not deliver fresh air into the barn on still days and do not create an even level of air movement over a given area.

Alternatively, a trained positive-pressure tube ventilation (PPTV) designer may be able to design a warm-weather PPTV system that would deliver fresh air at heat abatement speeds, spread over a larger area of the calf pens using fewer fans.

For these systems, we aim for 40 to 60 barn air changes per hour but recognize that in a large space it may be impractical to get more than around 20 to 30 air changes, an acceptable air-change rate for mild weather.

These PPTV systems will supplement natural ventilation through open curtain sidewalls. Some producers have also reported fewer flies on calves with the use of PPTV systems providing around 250 to 400 feet per minute wind speeds at 4 feet and closer to the floor (Photo 2).

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A naturally ventilated, east/west oriented barn

Hot weather for calves is about the same as for adult cows, with stress beginning at a temperature-humidity index of 68ºF. However, given the lower critical temperature of newborns is in the 50 to 60ºF range, ensure they are not chilled by a warm-weather PPTV system that is not turned off at night or on particularly cool spring or fall days.

A thermostatic control that engages a warm-weather PPTV system when the indoor barn temperature is above 70ºF will help ensure newborns are not chilled.

A list of Dairyland Initiative certified consultants able to design PPTV systems for calf barns can be found online.  PD

PHOTO 1: An example of a baffle board on a 4-foot concrete sidewall to deflect wind downward into the calf pens.

PHOTO 2: A naturally ventilated, east/west-oriented barn that has 12- to 14-foot curtained sidewalls with split curtains and a short 18- to 24-inch concrete base, coupled with supplemental warm-weather positive-pressure tube systems help keep a calf barn cool during warmer months. Photos provided by Courtney Halbach.

Courtney Halbach is an associate instructional specialist with the Dairyland Initiative with the University of Wisconsin. Rebecca Brotzman, MS, DVM, is the previous associate outreach specialist with The Dairyland Initiative. Ken Nordlund is a veterinarian with the University of Wisconsin School of Veterinary Medicine.

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