Most dairy farms in the U.S. use some sort of cooling mechanism in hot summer months to keep cows cool. It has been well documented that keeping cows cool in periods of heat stress can provide economic benefits in the form of improved reproduction and milk production.
The electricity and water used to cool cows doesn’t come without a cost of its own. However, the benefits of keeping cows cool outweigh the additional cost in energy. But, what if you could keep cows cool without the expense of electricity and reduce your water use?
Research projects in Arizona and California have been evaluating a new method of cooling cows called conductive cooling. So far, the results are promising and this new technology could offer dairy farmers an opportunity to cut energy cost.
How does it work?
Conductive cooling works through direct surface contact between a warm source and a cold source, transferring or exchanging heat to cool an animal.
Much like a dog cooling itself by lying on cold tile floors, heat is transferred from the dog to the colder surface of the tile floor. The same thing happens if you cool free-stall beds — heat would be transferred between the cooled free-stall bed and the cow.
To get the free-stall beds cool, a heat exchanger is buried approximately 12 inches below the surface of the free-stall. (Burying it 12 inches below the free-stall bed prevents it from being snagged by grooming rakes.) Well water (60 degrees F to 70 degrees F) pumped from an existing well passes through the heat exchanger system under the freestall bed on its way to another function on the dairy.
With about a 30 degree F to 35 degree F difference between the temperature of the cow and temperature of the well water, heat is transferred between the two, says Jim Bruer, general manager with Agriaire. Agriaire has a patent pending on this new cooling system.
Another way to cool free-stall beds is to use a chiller to re-circulate chilled water through the heat exchanger. Water would stay in this closed loop system and not be used for other purposes on the farm.
Concern has been raised that dampness through condensation might be an issue, says Tim Steele, primary engineer with Agriaire. “We’ve done a number of tests, using extreme temperatures and extreme humidities, and condensation in the bedding has not been an issue.”
Cut energy use
Energy to operate fans and pump water to cool cows is expensive. It is estimated that 10 percent of energy use on-farm is dedicated to air circulation.
While that might not seem like a lot, in California it has been estimated that summertime energy cost to operate fans is just over $17 million.
If conductive cooling is proven to effectively cool cows and implemented on dairies, the potential exists to significantly shift or reduce the peak load of energy required to cool cows and provide huge savings in summertime energy cost.
In September 2010, Agriaire worked with the University of Arizona, University of California and the Turlock Irrigation District to conduct a commercial scale test on a 3,600-cow dairy in Tulare, Calif.
The results of the limited California test indicate that conductive cooling, using supply water at approximately 70 degrees F to 72 degrees F, can effectively cool cows at ambient temperatures in the low 90 degrees F.
This indicates that when temperatures are in the mid-90 degrees F or higher, either cooler water must be supplied or some form of supplemental cooling method may be needed. Further testing with cooler water will continue this summer.
But, changing thermostats from 75 degrees F to 90 degrees F could have a large impact on operational hours of fans and energy cost. If the test dairy, using conductive cooling alone to cool cows up to 90 degrees F, turned on its 180 fans when the temperatures surpassed 90 degrees F, the dairy would save close to $26,500 in energy cost during the summer. This represents a 75 percent savings in energy.
“If you could turn your fans on even 10 degrees later, dairy farms could see a huge savings in energy cost,” says Todd Bilby, Texas A&M AgriLife extension dairy specialist.
But more work is needed using cooler water temperatures. Research is also needed using sand bedding; work to this point has been done using dry manure bedding only. Some of this research will commence at the new South West Regional Dairy Center in Stephenville, Texas, where conductive cooling is being installed in two of the 40-cow pens.
Reduce water consumption
Not enough work has been done to estimate the reduction in water usage on-farm. But the potential is there. Recent water use estimations on California dairy farms indicate that 40 percent to 50 percent of water is used for animal cooling and consumption.
An answer for humid climates
Even though the work so far has been shown applicable to the western part of the U.S., conductive cooling could have application in humid environments.
High humidity significantly diminishes the cooling effects of current conventional evaporating cooling methods (fans and misting). Conductive cooling offers dairy producers in humid climates, such as Florida, real promise to keep cows cool, says Robert Collier professor of environmental physiology in the Animal Science Department at the University of Arizona.
Cold weather application
There has been little research done on the impact cold stress has on cows, but conductive cooling, or rather conductive heating could have an application in cold climates.
In cold weather, a closed loop system would be used to circulate warm water through the heat exchanger. Heat from the water would be exchanged with the colder temperature of the cow, warming the cow up. Heating cows up could have potential to improve feed efficiency during winter months.
More research is still needed, but conductive cooling could offer a lot of potential for the dairy industry. The technology may also qualify for “green energy” tax incentives.