Calf Care Checklist: Calf Barn Ventilation

By Ann Hoskins, Vita Plus calf products manager
The key to a good calf barn ventilation audit is to evaluate the air quality in many different scenarios. Weather can change the calf environment quickly. Monitoring air should be part of your daily checklist. If problems persist, enlist a trusted consultant to assess your options.

Daily checks:  Look, listen, smell and feel.

1. Look to see how calves utilize the space in group pens.  They will lie where they are most comfortable. The goal is to have calves use the entire space available and not bunch in one spot. Things that could cause bunching include drafts, poor bedding and fly pressure.

Look at the bedding.  Ideally, you should not see the bedding actively move at the calf level.  The goal is still air speed, which is 60 feet per minute.

2. Listen to environmental noise, especially any type of mechanical ventilation. You can often hear if barn fans are not functioning properly. Fans should not make surging noises unless the wind is strong. That may indicate your hood is not the right size. Fans – like all other equipment – need maintenance. They should be cleaned at least once a year, preferably in late summer or the fall.

3. Smell the air.  Is it clean and fresh? This test should be done in the areas where the calves lie down. Get down to the calf’s nose level and smell what it is smelling. A smelly spot could indicate a ventilation dead zone or simply a need for more bedding. Bedding plays a big role in air quality.

4. Feel the air movement at the calf level.  Do you feel the drafts? Spend some time in the pens with calves.

Tools to help
Put some metrics to your senses. A few tools can help put numbers to your observations.

1. Wind meter and anemometer:  A wind meter will help you identify areas of concern as it measures air speed and variability in a barn. Again, focus on areas where the calves lie down. You can also measure areas by tubes and fans, but a hotwire anemometer is more sensitive and provides better information. When using these tools, it is important to take measurements in various weather conditions and areas of the barn, including the walk area. The goal is to have consistent numbers throughout the facility. Work with a trusted consultant to evaluate the data you collect.

2. Bug fogger:  Another option is to “smoke” the barn. We use mineral oil in a bug fogger to fill the barn with smoke.  Ideally, we would fill the barn with smoke through tube fans if installed. Not only does this show how air moves in the barn, but it also helps us evaluate the tubes. In the tubes, we are looking for even distribution, air leaks at connection points, air surging from the holes, and where the air goes.

When smoking a barn, we also look for changes per hour or how often the air completely turns over. In cold weather, we want air to change four to six times per hour.  In the summer, we would like it to change 40 times per hour. To measure this, start a timer once the last puff of smoke enters the barn. When the air is clear, stop your timer.  Divide 60 minutes by the number of minutes it takes for the smoke to clear.  For example, if it takes 15 minutes for the smoke to clear, the barn has four air changes per hour (60 / 15 = 4).

Safety is of the utmost importance when smoking a barn.  Work with a consultant who is experienced in the process and knows how to do it as safely as possible.

3. Ammonia strips:  Ammonia strips can be used to measure ammonia concentration, which can affect health and growth, and evaluate bedding moisture. Tear off a 1-inch piece of ammonia strip and wet it with clean water. Wave the strip 1 foot above a bedded pack area for 20 to 30 seconds and then wait 15 seconds. Compare the strip color with the color chart on the package. The target is less than 5 ppm ammonia in calf facilities.