The question was asked –
“I am under the impression that evaporative cooling only works at certain humidity levels. That there are definitely situations/climates where misting is preferred over evaporative cooling and vice versa.”
I asked Professor John Bernard of the University of Georgia to answer the question.
Here is his answer.
"Your location (an area in North America with high summer humidity) is characterized by high humidity (average range of 71 to 85% throughout the year) and lower temperatures (max average of 74.4°F). The high humidity in your area and lower temperature will limit the number of days during the year that you need to use evaporative cooling compared to many areas where evaporative cooling is used, but the ability to do this is important for both lactating and dry cows.
The concern with reduced efficiency with the mister system is a valid concern as the efficiency of evaporative cooling decreases (for all systems) as the humidity increases.
I worked at the Tifton Dairy Research Center for 22+ years that used a mister system for cooling cows which worked well. (A very hot and humid area in the summer months)
Many producers asked us why we chose misters rather than a soaker system was given the high humidity. In our case, we looked at the research and knew it could be as effective for reducing heat stress as a soaker system, but it used less water which reduced the size of the lagoon that had to be built.
Other factors may be just as important as the efficiency of a specific cooling system.
Will the system cause any water availability issues with your current system? If building, you can plan for total water use and size the water lines appropriately, but if you are installing a new system in an existing barn you don’t want to reduce water available for cows to drinking that could limit milk yield.
What impact will the system have on total water cost and does your waste system have the capacity to handle the additional wastewater generated.
There are not many controlled research studies comparing soakers and low-pressure mister systems.
1. Auburn University conducted a study several years ago and did not observe any difference in body temperature or performance of cows cooled using either a soaker or low-pressure mister system along with fans.
2. At UGA, we compared the Core Cool System with our system that included 36-inch fans fitted with a pressurized (180 psi) mister system over both the feed alley and freestalls for 120 cows.
- There were no differences in body temperature (average 102.39°F),
- Respiration rate (57.6 breaths/min), or
- Milk yield (77.8 lb/d) of the cows.
- Water use was much lower (5,624 L/d) for the Core Cool System compared with the control system (9,008 L/d).
- The dry matter content of the sand was similar for both systems (93.7 and 94.5 for control and Core Cool System systems, respectively).
- During the trial, the temperature ranged from 68 to 86°F and relative humidity ranged from 55 to 98%.
3. Researchers at the Miner Institute observed that cows used the freestalls more and spent less time standing when the Core Cool System system was used over the feed alley and freestall compared with a soaker system over the feed alley only.
Either the soaker or the Core Cool systems can work for you.
Like anything, properly managing the system is key to obtaining positive results. The final choice in your situation may be related to other considerations besides effectiveness."
If you would like to learn more about cooling cows effectively using a fraction of the water soaker systems use, then contact Core Cool Systems at 1-844-438-5845 to talk to an expert on cow cooling.