October 15, 2019

WHY WHO DESIGNS YOUR CALF BARN VENTILATION MATTERS

Most farms are familiar with the concept of natural ventilation (open side walls) supplemented by positive pressure air tubes as a standard of acceptable ventilation strategies in youngstock barns.  Hundreds of trainees from around the country have gone through the popular ventilation training offered frequently by the Dairyland Initiative – including myself.

Before reaching out to one of these trainees to help design your tubes, think twice.  The Dairyland Initiative offers a Certified Consultant status in addition to this training – the next step, which requires the trainee to complete a set of designs and reports which are reviewed by the Dairyland Initiative team, as well as periodic submissions of current tube designs and the accompanying reports to confirm that the ventilation design is correct for the animals, barn, and overall needs of the facility.  Want to know how many people in Minnesota are actually Certified Consultants?  Only two –I am one of them.

As with any training, attending does not always mean comprehending.  Here are some of the common errors I have seen in recently installed tube systems:

The fan diameter and tube diameter are the same.

          The problem: When both the fan and the tube diameter are the same, physics comes into play and the first 20 feet of the tube or so will have poor air flow out of the holes.  When most barns are around 80-100 feet, can you afford to sacrifice air flow to ~25% of your calves?

The air flow is designed for only 4.0 air exchanges per hour.

          The problem: 4 air exchanges may be considered to be adequate by some.  However, the minute one extra calf enters the barn (or more realistically, 10 extra calves during heavy calving), or the fans are a couple years old and not running at full capacity, or have some dust on them, the air exchange drops and is inadequate.  Many farms I work with feed calves 2+ gallons of milk/day, plus free choice water, and the output of these calves is tremendous.  I err on ventilations toward 5-6 air exchanges per hour to account for both the increase moisture in the barn, and fan failures / heavy stocking density times.

Bedding height is forgotten.

          The problem:  In the Midwest, straw is the primary bedding.  When we target an airflow to slow to 60ft/min or less at 3-4 feet above the calf, we may need to account for 1-3 feet of bedding/pack above the actual floor (which certainly does happen in some weaned calf barns in the winter!)  The point of ventilation is to delivery fresh air to the calf – without a draft.

Pen Style

          The problem:  I have reviewed some systems that were designed to have an air puff directed to the front of the pen – while forgetting that some pens have more solid fronts than others and ultimately do not let nearly as much air in (Calf-tel comes to mind).  While the new standard is both an open front and back pen and this could be remedied, this can be a major barrier to air flow.

There are many factors to ventilating a calf facility – let’s visit in person to review your system (and the drainage!).  Find a list of Certified Consultants on the Dairyland Initiatives website:  https://thedairylandinitiative.vetmed.wisc.edu/professionals/industry-contacts/

Rebekah LaBerge

by Rebekah Mathews

Calf & Heifer Specialist

Ag Partners & Western Wisconsin Nutrition