Managing Heat Stress

Cows

As temperatures rise, producers may need to pay closer attention
to their synchronization programs.

Working cattle in hot weather can be detrimental to heat synchronization and artificial insemination (AI) programs, says Julie Walker, beef specialist for South Dakota State University (SDSU). When cattle need to be moved or worked, it pays to watch weather forecasts and try to choose a day that won’t be during a heat wave. Sometimes, however, producers need to get cattle in for a heat-synchronization program, and timing is crucial, regardless of the weather.

Walker says more producers are shifting to April-May calving to match forage with nutritional needs of the lactating cow and to reduce labor at calving to avoid having to worry about cold weather in February-March. Now, she says, they have to deal with the heat instead.

“They are breeding cows in July and August — which are often the hottest months, Walker explains. “This means that if they are putting CIDRs® in and synchronizing, and have to pull the CIDRs at a given time, they are under the clock and may have to get those cows in when it’s very hot. If they are going to do a fixed-timed AI in the morning, they are probably going to be pulling CIDRs at 7 p.m. the evening before.”

This can translate to more time and labor, particularly if cattle are away from AI facilities, she says. “If the cattle are not very close to the corrals, and we have to pull CIDRs at 7, this might mean we have to go get the cattle at 4 or 5 p.m., and that’s still during the hottest part of the day. We won’t be able to give them any time to rest and cool down and rehydrate because we have to sort off the calves before we put the cow through the chute. This often equates to 3 hours of working those cattle in the heat of the day,” she says.

Think about the heat and plan ahead, Walker urges. Consider moving cattle closer to the corrals in the morning while it’s still cool. That way, cattle are refreshed and watered before being worked, and maybe moving them will take less time. When moving and working cattle that time of year, make sure there is ample clean fresh water for them, so they won’t have any hesitation about drinking and getting rehydrated, she says.

If you’re using a fountain-type tank, make sure there’s enough water pressure to keep it full, Walker says, and make sure calves can reach the water.

“We always need to think about heat stress and take care to minimize it while moving or working cattle, because heat stress can impact reproduction,” she says. “A lot of the risk is during early pregnancy for cows, and heat also has a negative impact on bull fertility.”

Producers should also take into consideration that if you are doing heat detection during hot weather, cows won’t be very active during the heat of the day; they will be lying around in the shade to stay cool. You’ll have your best luck checking cows early in the morning or late in the evening, Walker notes, and they may be most active at night.

“When breeding cows that late in the summer when it’s hot, it really helps with the heat detection to use patches on them, to know which ones have been ridden,” she says. “We may not be out there during the coolest part of the day or night to see the riding activity, so we can use that tool to help us identify the cows that need to be inseminated.”

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Editor’s Note: Heather Smith Thomas is a cattlewoman and freelance writer from Salmon, Idaho.

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