Sorry – it's time to think winter
Winter ventilation in any dairy barn means keeping the air as dry as possible. While warmer air does hold more moisture, it is not enough reason to close the building up to keep it warmer
Even though most farms are in the midst of fall harvest and other crop-related work, livestock producers also need to be thinking "winter". They should be looking at their facilities and equipment well ahead of winter weather to be sure the systems are ready to deal with the extremes of winter and provide the best possible winter environment for their livestock. The occasional rainy days during harvest, or the time you are waiting for equipment and crop maturity to come together make good days to look over the livestock operation and take any corrective actions necessary. Here are a few things to check on those rainy days.
Many small to medium-sized dairies still use tie stalls. These buildings can provide nice, comfortable working conditions for the human operators during cold weather, but those same conditions may be detrimental to the cows in the winter.
Without even talking about ventilation rates, the equipment in place needs to be in proper working condition. Fan blades should be clean for easy airflow. Louvers designed to prevent cold air inflow can also restrict warm, moist air exhaust if they are dirty, bent so they don't open, or blocked in any manner. Clean fans and motors will run cooler and more efficiently. A dirty fan may have its airflow capacity reduced by 40%.
Proper ventilation is almost more about air inlets and air distribution than it is about exhaust fans. Especially for winter ventilation, air distribution needs to be uniform around the dairy barn so dead air spots with high moisture air don't develop.
Air inlets come in a wide range of designs from simple holes cut in a wall or hay mow floor to sophisticated, counter-balanced air inlet valves. It makes little difference what system you use as long as it provides enough air distribution around the barn. Be sure air passages are not blocked by dust, feed, collapsed ducts or dead critters that have collected over the seasons.
Winter ventilation in any dairy barn means keeping the air as dry as possible. While warmer air does hold more moisture, it is not enough reason to close the building up to keep it warmer. That extra moisture in the air is what causes so many respiratory problems in cattle. Minimum fans and air inlets need to be operating at all times to keep moisture moving out of the barn. To prevent some problems with air restriction, continuously running fans should have louvers taken off. If the louver isn't there, it can't get dirty and slow air exchange.
Continuous fans don't need thermostats, but other types of fans are usually on thermostats to turn them on as needed. Contact points in thermostats corrode easily when they aren't being used regularly. Check that thermostats are clean and their contacts are working properly. Replace thermostats that simply won't work after routine cleaning.
The more common housing today is a freestall barn, and usually that is a cold barn. Cows can be productive at temperatures well below 20 degrees Fahrenheit if they are kept dry and sheltered from harsh winds. Freestall operators have some common mistakes which should be avoided. Three of these mistakes are:
- Limiting ventilation to prevent waterers from freezing. Find other ways to keep the water running. A barn warm enough to keep water running will usually be a barn with respiratory problems in the winter.
- Limiting ventilation to keep manure from freezing. Manure may freeze a few days in the coldest part of the winter, but your cows are much better off if you prepare some alternatives for the manure handling rather than keeping it warm in the barn so the manure won't freeze.
- Limiting ventilation to prevent drafts. Cold, naturally-ventilated barns depend on airflow to keep moisture moving out of the barn. If the barn houses younger livestock that need extra protection, consider some sort of plywood hovers or partitions that limit airflow within the pens, but not through the building. Curtain barns are intended to restrict some airflow in cold times without cutting off all airflow. Let the barn work the way it is intended.
While it may be tempting to close down the open ridge of a naturally-ventilated barn, that open ridge is what keeps the barn dry. Warm, moist air needs a place to escape, and that place is the open ridge. Cold freestall barns are intended to operate between 5 and 10 degrees warmer than the outside temperature.
If the weather becomes extreme and you feel you have to cut down the air exchanges even a little, it would be better to put restrictions on the sidewall inlets (at the eave level). Do not close them entirely, however, or you will prevent proper airflow out the ridge. If the inside temperature of the barn is more than 10 degrees higher than the outside temperature, you are probably shutting the airflow down too much.
If your barn's open walls are controlled by curtains, this is a good time to unroll the curtains for inspection. Look for tears and holes caused by rodents. Are all the mechanics working properly? If you have an automatic system, see that it opens and closes properly. If you have a manual system, open and close your sides as well. If lubrication is called for, this is the time to do it.
Are the eave openings on your barn continuously open or are they variable? Look at how you can close them part way if an extreme cold spell calls for some air inlet restriction.
Waterers were mentioned earlier. It is far easier to check and repair a heater element in a waterer now than it is in December. While checking the heating elements, check the wiring as well to be sure all wires are well-insulated and the system is properly grounded to prevent stray voltage problems through the waterers.
Published in Dairy Star October 9, 2004