Water Your Crops … and Your Cows

Research suggests using center pivot irrigation systems for cow cooling. ( Clinton Griffiths )

Center pivot irrigation systems water field crops … but can they also water your cows?

A researcher at Mississippi State University says placing a mister attachment on a center pivot irrigation system in your pasture would provide cows evaporative cooling while still allowing them to graze.  

“Cows will typically stay under it until they are cool, then go graze,” says Amanda Stone, an assistant dairy science professor at Mississippi State University. “We’ve been studying the effects of this system from a physiological and behavioral standpoint and see clear differences. One benefit I hadn’t really expected to see so clearly are much cleaner cows because they’re not making mud holes to cool off.”

Dairy cattle experience heat stress at a temperature humidity index (THI) of 68 or higher, Stone says, but there is little research on the effects of heat stress on cow health or how to best mitigate heat.

“Heat stress is a production and welfare issue for cows and an economic issue for producers so finding ways to minimize the stress is important, particularly in pasture-based systems where we can’t install the freestall system of fans and sprinklers,” Stone says. 

Dairy cattle may not be the only beneficiaries of such cooling systems, she adds.

“Even for beef cattle it could have a purpose,” Stone says. “They get heat-stressed, too, but are given less priority because we aren’t noticing the sudden drop in milk yield that we do in heat-stressed dairy cows.”

There is no one ideal farm for this cow cooling system, but it is most economical when farms already own a center pivot irrigation system or are looking to expand their herd, Stone explains.

“One of the good things of center pivot irrigation is that it’s good for crops,” Stone says. “If a dairy farm eventually goes out of business, it can still be used for irrigation.

Building a freestall barn would be much more expensive and permanent.”

Once the irrigation system is established, Stone says producers can expect to spend just a few minutes per day for upkeep.

“It can be as automated or manual as you want it to be,” she says. “A lot depends on the company selling the system. Some of them can even be controlled electronically based on the weather.”

There are typically three main areas of maintenance, Stone says.  The systems can be top-heavy and fall during storms, they may become stuck on electric fence wiring, or they can occasionally run over cows, she explains.

“These systems move slowly, but that actually has happened before,” Stone says of cows getting hurt by the wheels. “Some farmers put an electric shock at the wheels to make the cows get out of the way.”

Stone says her team of researchers are finishing a study comparing cow health under three systems: no shade, simple shade or water mist.

“We are analyzing data on cow activity and behavior, milk production, and white blood cells and the immune system,” Stone says.

This will build on previous research at Mississippi State University evaluating the economics of using center pivot irrigation systems for cow cooling, she says.

“I wish there was a larger investment in heat stress research because it’s a big problem in our industry,” Stone says. “But I think interest is increasing in heat stress because temperatures are rising.”

To learn more about using center pivot irrigation systems for cow cooling, as well as the researchers’ economic analysis, visit the Mississippi State University Dairy Extension website.

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