If you’re a cow, evaporative cooling is your best friend when temperatures climb — especially in the holding pen during the heat of summer.
Cooling in this area is vital because a holding pen is like crowding a bunch of 101.5-degree ovens together, says Todd Bilby, Texas A&M University extension dairy specialist. It doesn’t take long for things to heat up.
Cows experience heat stress whenever the temperature-humidity index climbs above 72. And when cows are confined in holding areas for 15 to 60 minutes (or more), two or three times a day, stress can occur under even moderate ambient temperatures.
Here’s why you need to properly cool these areas.
Decrease cow temperature
You may think that fans or water would be sufficient to cool cows in this area. But, cows preferentially use evaporative cooling to deal with heat stress, explains Bilby, so the addition of water and fans helps an already in-place mechanism to work even better. “You don’t get the full effect with water or fans alone,” he says.
Research at the University of Arizona shows that the addition of fans and overhead sprinklers to the holding area reduces internal cow temperatures by 3.5 degrees Fahrenheit. During the study, the sprinklers ran continuously at a rate of about 3 gallons per hour, and fans provided air flow of about 1,000 cubic feet per minute.
Similar results were found recently at the University of Wisconsin, where researchers surveyed heat-abatement strategies and the impact on several herd parameters in free-stall barns in the Midwest and California. This research, presented at the American Dairy Science Association annual meeting last summer, has been submitted to the Journal of Dairy Science.
The holding pen was identified as a major risk area for elevated internal body temperature, says Jon Schefers, University of Wisconsin dairy science graduate student. He found that airflow rates in the holding area were associated with mean within-herd internal body temperature. In other words, as the airflow rate increased, the average within-herd internal body temperature decreased.
Additionally, “It is likely that cooling strategies used elsewhere on the farm cannot compensate for heat stress that occurs at this time,” says Schefers.
“We seem to be failing in the holding area,” adds Nigel Cook, University of Wisconsin veterinarian. Therefore, it is appropriate to add cooling to this area of your dairy if you haven’t already. And, check your system’s efficiency to ensure that you are getting the maximum effect.
Increase milk production
When holding pens are cooled, internal cow temperatures go down and milk production goes up.
The University of Arizona research shows a 1.7-pound per day increase in milk production for cows that were cooled in the holding pen versus those that did not receive cooling. An Israeli study found that milk production rose about 4 pounds per day if cows were cooled in holding pens five times daily.
Even using the more conservative outcome, the production increase equals financial opportunity. Arizona data indicate that return-over-investment was realized in less than one summer season.
According to the University of Arkansas, if you get a 2-pound increase in milk per cow for 80 days after cooling in the holding pen, and milk is $13.50 per hundredweight, you’ll see a gross income increase of $2,160 for every 100 cows. You’ll need to factor in your expenses, of course.
Still, holding pen cooling is something to look into whether milk price is high or low, says Bilby. “When prices are high, it’s important to maximize milk output. When prices are low, it’s still important to maximize milk output without significantly increasing your cost. Cooling the holding pen is a cheap way to do just that.”
You may also improve your herd’s reproductive performance by adding cooling to your holding pen.
It’s no secret that heat stress depresses reproductive performance. In general, heat stress is negatively associated with altered duration of estrus, uterine function, endocrine status, follicular growth and development, early embryonic development and fetal growth.
It’s not unusual for herd conception rates to drop five to eight percentage points between spring and summer, says Cook.
Until now, no direct correlation has been made between holding pen heat stress and reproductive performance. But the University of Wisconsin data now indicate there is a connection — at least when it comes to service rate.
Results show that herds that used soaking systems in the holding pens submitted 3 percent more cows to artificial insemination than herds without soaking systems. It should be noted that 24 of the 30 herds examined in the study used both fans and soakers in the holding area.
“This highlights the general importance of heat-stress abatement, especially in larger herds,” notes Schefers.
Learn more about the new tools and concepts for monitoring heat stress on your dairy.
How to accomplish holding-pen cooling
The cooling of holding areas is pretty straight-forward and economical. To learn how to design holding pen cooling systems and mistakes to avoid: