Every season brings new and different challenges to farming operations in the Ozarks, and summertime is no different.
With summer comes heat, humidity and sometimes drought – all things that can cause heat stress in livestock.
Heat stress can cause many issues for a stockman, and it pays to be able to recognize signs of heat stress in your animals so that you can take immediate action if it occurs. Failure to recognize heat stress can be costly.
“One of the largest costs of heat stress is reduced fertility,” said Reagan Bluel, University of Missouri Extension Regional Dairy specialist for Southwest Missouri. “Fertility is primarily compromised through early embryonic loss and can be a direct result of heat stress. In extreme cases, this condition can even cause death.”
Heat stress occurs when the body cannot cool itself enough to maintain a healthy temperature.
Over exposure to hot, humid conditions, or being in cramped quarters on a hot day with poor ventilation can cause heat stress in livestock.
“Heat stress shows itself in several ways. High respiration rates, drooling and open-mouth breathing are classic visible signs,” Eldon Cole, University of Missouri Extension Livestock specialist said. “Of course, checking body temperatures is another way. The normal cattle temperature is 101.5 degrees. Under heat stress conditions the temperature may rise to 105 or more.”
Bluel noted that cows suffering from heat stress “often will stand more, which could have long term effects on hoof health that you might not see until early fall.”
If possible, cattle and other livestock will try to alleviate heat stress on their own.
“Stressed cattle seek shade, mud holes, ponds, creeks and good air movement,” Cole said.
Livestock suffering from heat stress will often go off feed as well.
To combat heat stress, producers should make sure they are providing livestock with plenty of fresh water and plenty of shade.
“Fortunately, in grazing situations like we have in Southwest Missouri, we have shade trees in most pastures so we may not have heat stress symptoms like a feedlot experiences. But you still need to observe cattle on a regular basis especially when temperatures exceed 80 degrees. High humidity readings add to the stress level,” Cole said.
“Cattle that are not shed off completely and are on fescue pastures that contain toxic alkaloids also are prone to heat stress. These cattle need to be given special attention and have plenty of water and shade. Some even clip or shear them, much as you would a sheep,” he added.
Finally, be aware of the situations you place your livestock in during the hot summer months.
“Stress levels may get serious when working cattle or hauling them. Pay especially close attention at these times and work them in cooler parts of the day,” Cole cautioned.
Stages of Heat Stress in Cattle
State 1
• Elevated breathing rate
• Restless
• Increased standing time.
Stage 2
• Elevated breathing rate
• Slight drooling
• Most animals standing in pen and restless*
• Animals may group together*
Stage 3
• Elevated breathing rate
• Excessive drooling or foaming
Stage 4
• Elevated breathing rate
• Open mouth breathing
• Possible drooling
Stage 5
• Elevated breathing rate with pushing from flanks
• Open mouth breathing with tongue protruding
• Possible drooling
Stage 6
• Open mouth breathing with tongue protruding
• Breathing is labored, and respiration rate may decrease
• Cattle push from flanks while breathing
• Head down
• Not necessarily drooling
• Individual animals may be isolated from herd
* Note: This symptom may be seen in multiple stages.
