Heat stress is known to cause a number of health and behavior problems in dairy cows, including:
- Decreased dry matter intake, resulting in weight loss
- Decreased milk production
- Decreased reproductive efficiency
- Decreased blood flow
- Increased respiration rates
Heat stress is such a critical issue that preventing it should be a top priority for both dairy producers and those of us developing new barn technologies.
The cow’s body is like a giant radiator, dissipating heat over a large surface area. She instinctively knows she feels cool when air is moved past her body, so she seeks out places with moving air. She instinctively knows she feels cool when water soaks her body, so she seeks out places with misters or sprinklers.
Unfortunately, many of the technologies dairy producers use today can’t fully dissipate the heat generated as the cow performs her daily activities. Her body temperature rises despite fans and water, and she becomes stressed and uncomfortable.
Reducing heat stress in the dairy barn of today
As producers look to build or renovate their facilities, each barn should be evaluated to determine how best to achieve cow comfort – including a special focus on eliminating heat stress. In most barns today, this will mean a combination of water spraying/drenching and fans.
To minimize or eliminate heat stress, all areas of the barn must be addressed – the feed alley, the stalls, the holding area and the parlor/milking center.
Air flow alone (usually) isn’t enough
A 2005 study on heat-stressed dairy cows concluded fans alone do not adequately cool cows; it takes a water spray as well. To do the best job of reducing stress using existing technologies, fans and water must generally work together.
At the bunk, it is common to use a combination of misters or soakers and fans. While improvements in fan designs and spray patterns have improved, this is an older technology with limitations.
Due to these constraints, look at effective, durable and reliable fans with water application technologies that are efficient and focused on reducing excess water. There have been improvements in tunnel ventilation systems that have demonstrated significant air-only reductions in heat stress, but this requires a completely new barn build.
Cool everywhere
Aside from milking, cows spend about half of their time in the freestalls (nine to 16 hours), either standing or lying down, and the other half of the day in the alley (nine to 16 hours) eating, drinking or standing.
When renovating or building a barn, look at every space and consider air flow and cooling technology application to reduce stress across the cow’s entire daily experience.
Small time, big impact while milking
Producers may not invest enough in reducing heat stress in the holding area and return alley; the cow is only in there a relatively short time during the day, after all. However, it is critical to minimize heat stress through the milking cycle. First, in the holding area, cows can heat quickly due to crowding in the confined space.
Add this to the stress of standing, jostling and milking, and her body heat and stress levels may continue to rise. Second, for every degree a cow increases in temperature, it takes twice as long for her to cool and get rid of that one degree. To combat this, pay extra attention to the holding area’s fans, ventilation, air flow and water application, and get the cow to a cool zone immediately after she leaves the parlor.
More water isn’t better
Some companies promote a full drenching of the cow after she leaves the parlor, while others promote misting cows while in the freestalls.
In the post-milking return alley, the drenching sounds logical – until one thinks of the potential for bacteria to enter the teat canal after milking, as it isn’t given time to seal. Be cautious at this sensitive time and invest in technology that doesn’t overdo it.
In the freestall, there is a concern about how the heat of the cow, the organic matter in every dairy environment and the addition of misting technology will promote environmental bacteria growth.
Producers must research and be honest about how adding moisture in the freestalls will impact the farm. While it may very well be that low bacteria growth results are achieved using this technique in a studied barn during research, producers must ask themselves these tough questions:
- Will my own management practices support the same results?
- Am I already achieving an exceptionally low level of wetness in the stall and feel confident that I can manage adding moisture?
- Will my bed surface itself and the top bedding I use be supportive of adding moisture?
- Will the air exchange in my barn allow for this method of cooling cows?
It is imperative when making any kind of change to your barn conditions to do your homework before assuming what works for one will work for you.
Reducing heat stress in the dairy barn of tomorrow
As existing technology demonstrates, it is relatively easy to cool cows with fans and water at the feedbunk and the holding area, but what about in the parlor and the stalls?
Cooling off while being milked
The conventional parlor requires human intervention, so from a practical point, cooling cows there is not a viable solution. However, robotic milking in parlors may provide an opportunity to cool cows while they are milked. This potential may give robotic milking an entirely new benefit.
Cooling off while lying down
As a distributor of dairy bedding solutions for more than 20 years, I am always searching for new technologies or management innovations that could help reduce heat and heat stress while the cow is lying down.
She is in the stall for 50 percent of her time, and comfort plus cooling could provide an unprecedented level of stress reduction with a breakthrough in affordable, scalable cooling in the stall. The search continues.
Less and less water available for cooling
So far, we have only discussed the cow side of the cooling equation. What about the water after it has left the nozzle? Where did it come from, and is that source sustainable? Where will the water go? Are there water scarcity or environmental issues to be concerned with?
We are all aware of the issues surrounding groundwater procurement and discharge. In some parts of the world, water is already a scarce commodity, and that is not likely going to change. As populations creep into what was once considered rural territory, there is competition for water that never existed before and more pressure put on dairies to become sustainable in their use and discharge of water.
If we keep drenching or soaking cows the same way as we have done for the past 20 years, pressure from environmental regulators will continue to increase. In the future, we must become more efficient at the initial start of the cooling process, more innovative at the discharge end and explore sustainable technologies that don’t rely heavily on water.
In general, our industry has not done enough to advance the cooling of cows, especially in the freestalls, holding areas and milking centers. We recognize the need for cows to lie down and the production, reproduction and health benefits, yet we have done very little to adapt cooling techniques to cows in this phase of their day.
And we continue to rely heavily on increasingly scarce water resources in many areas, so innovation in low-water or no-water solutions is much needed.
Cooling cows is critically important. In dairy barns of today, do what you can within the confines of your barn design to reduce heat stress using efficient, available technologies. Plan your new build with heat stress, water availability and water discharge in mind.
Meanwhile, we all – producers, innovators, researchers – must focus on finding ways to cool cows that are sustainable and efficient for the future. PD
References omitted but are available upon request. Click here to email an editor.
PHOTO: In the future, we must become more efficient at the initial start of the cooling process, more innovative at the discharge end and explore sustainable technologies that don’t rely heavily on water. Photo by Ray Merritt.
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Dean Throndsen
- CEO
- Advanced Comfort Technology Inc.
- Email Dean Throndsen
