Last summer’s heat wave left many of us with an increased appreciation for cooler weather. If you, like us, had the good fortune to spend July and August under that little weather novelty known as the “heat dome,” 2011 was an exercise in creatively keeping cool. Humans have air conditioning, swimming pools and ice cream shops to help us keep cool, but what about livestock? How do they adapt and take care of themselves during such extreme heat? And what livestock-management techniques can we use to help?
How animals keep cool in high heat
Like humans, some livestock tolerate heat better than others, and each species has adaptive strategies that help it manage the high temperatures. Sheep and goats tend to tolerate hot weather quite well, especially fat-tailed breeds of sheep such as the Karakul. The wool coat, which to us looks profoundly uncomfortable during the summer months, provides wonderful insulation against extreme temperature; the heat never makes it down to the sheep’s skin. Shearing in the spring before the onset of hot weather will prevent the sheep from experiencing sunburn, which would be a risk if they were sheared in the heat of the summer.
Horses have a nearly legendary ability to sweat, and as long as they are not being asked to perform intense physical activity during the heat of the day, they generally tolerate hot, humid weather well. The sweat allows them to take advantage of natural ventilation, via wind, and they can be seen comfortably grazing on hot days when other animals have retreated to the shade.
Cattle, on the other hand, have a limited ability to sweat, and therefore need shade and ventilation to keep cool. They will actually increase their respiration rate in order to try to get rid of more heat. Cattle breeds with lots of floppy skin, such as the Zebu or Ankole-Watusi, handle heat well because the loose skin provides extra surface area for cooling. Breeds such as the Pineywoods, Texas Longhorn and Florida Cracker have been shaped by their environment to handle heat stress quite efficiently as well.
Like cattle, pigs have limited sweat glands. While panting is not a very efficient method of cooling for them, they have learned to cool themselves by wallowing in mud. The phrase “happy as a pig in mud” is quite accurate, but “sweating like a pig” is nowhere near true.
Domestic rabbits are another species that need to be carefully monitored during extreme heat. They don’t sweat, and they rely on panting and radiating heat through blood vessels in their ears to cool themselves. Breeds such as the American are known for their large ears, which give them a big advantage in hot weather.
Chickens will pant (gular flutter) and spread their wings to reduce the amount of body heat trapped near their bodies. Free-range birds will find a cool spot to hang out during the heat of the day, but birds in confinement will need additional ventilation to help offset the heat. If you have a mobile chicken pen, try to park it in the shade on warmer days, or let the birds out to pursue their own reprieve during the daylight hours.
Summer livestock management: what you can do to help
One of the key things you can do to minimize heat stress in livestock is to provide shade for your animals. This can be as simple as taking advantage of natural shade, such as a large clump of trees, or as involved as building new structures. Shade cloth (available at most hardware stores) can be easily stretched over a wooden frame, creating shade quickly in nearly any location.
Ventilation is also an important factor in keeping livestock cool. A good natural breeze can provide sufficient cooling to keep animals comfortable, but animals in confinement will need additional ventilation. Fans are essential in a rabbitry or a confined poultry house to keep air flowing freely. However, when possible, situating a barn or coop where it can take advantage of prevailing breezes will help it stay cooler — and also will help make your electric bill look better. Large fans in big livestock barns can be expensive, but it sure beats losing an animal to heat stress. Misters can be helpful in cooling the air from the fans, but be sure you don’t make the humidity problem even worse; allow the misters to run for a time and then shut them off so water doesn’t pool in the area.
Water is the most important basic necessity — even more so than food. An animal can sometimes survive for weeks without food, but only two to three days without water, especially in the heat. Cold water can cool the animal internally and help regulate body temperature. Animals can increase their water intake by 50 percent in hot weather, so providing plenty of fresh water is essential. Lactation stress also will increase water consumption, so make sure nursing animals have plenty of water available at all times, just like you would do at other times of the year.
The water should be cool and clean, helping entice the animal to drink more. During a prolonged hot spell, ponds can get warm, making them unappealing to animals, so an additional water source is a good idea. Fresh water also will encourage consumption, so be sure to clean water tubs and tanks regularly; this will keep them algae-free as well. Providing species-specific salt and trace mineral blocks also can help increase water intake, as well as help keep animals’ electrolyte levels balanced.
Some simple husbandry changes are essential during hot weather. Weaning, which is a stressful period in an animal’s life anyway, would be best performed prior to the onset of hot weather or left until cooler temperatures return. When working livestock during the hotter months is unavoidable, try to do it as early in the morning as possible, when it’s cooler, and quit before it gets too hot. Keep in mind that young animals do not thermoregulate nearly as well as their adult counterparts. For example, a young foal following a pacing mare along the fence line in hot weather can quickly become overheated. Transporting animals is best accomplished either early in the morning or after dark — and make sure all the ventilation holes are open on the trailer. Elderly animals also will need special care in extreme heat, similar to that required by youngsters.
How hot is too hot?
Most animals have a comfort range of about 40 to 80 degrees Fahrenheit, which is where they can maintain their normal body temperature without expending a great deal of energy. However, humidity can have a dramatic impact on how effectively an animal can cool itself. In fact, high levels of humidity can often be more detrimental than high temperatures. Humidity prevents animals from efficiently cooling via panting, as the already humid outside air cannot absorb as much warm moist air from the lungs, and the animal has to pant harder to achieve the same rate of evaporative heat exchange.
For animals that can sweat, humidity will keep sweat from evaporating well. A table showing the critical junction between heat and humidity is available online at The Samuel Roberts Noble Foundation.
So, despite your best efforts, what can you do if you have an animal experiencing heat exhaustion or heat stroke?
The signs and symptoms of heat-related problems are generally muscle tremors, weakness and collapse. In a case of heat stroke, the gums and lips may be bright red, and the animal may have a vacant, staring expression. It will have an elevated body temperature and may have labored breathing.
The first thing to do when you find an animal experiencing severe heat stress is to begin cooling procedures immediately. Move the animal into the shade, if possible, and get a fan going to increase evaporative cooling. The quickest way to get an animal cooled down is by immersion in cold water — or for larger animals, running cool water from a garden hose over them. If possible, take the animal’s temperature — and continue to take it every 10 minutes throughout the cooling process.
The animal must be soaked continually, getting it wet down to the skin. Keep applying cold water until the core body temperature begins to drop. If soaking the entire animal is not practical, apply cool water over areas that have a large number of sizable blood vessels, such as the jugular vein in the neck. Start by running water over a small area rather than suddenly immersing the entire animal all at once to avoid shock. Sudden and widespread exposure to extremely cold water can cause blood vessels throughout the animal’s body to constrict, making it even more difficult to continue to dissipate heat and making a bad situation worse.
If cold water is not available, rubbing alcohol will work if applied over the large veins in the neck or between the legs, but it will take a good amount of alcohol to cool the animal enough to lower its body temperature. Once the animal’s body temperature begins to approach normal, stop cooling efforts and monitor it closely, offering it small amounts of water to drink until it has recovered.
The human element
Let’s not forget the human element in all of this. Many times, good herdsmen get so involved in caring for their livestock that they forget to take care of themselves. Be sure to take frequent breaks in extreme heat, and don’t wait until you are thirsty to increase your water consumption. After all, you won’t be able to help your animals if you are down and out yourself.
For many of us, hot weather is a fact of life. By taking a few practical steps now, however, you can protect yourself and your animals from most of the ill effects of Mother Nature’s hot flashes.
By day, Callene Rapp is a senior zookeeper, and by night she manages The Rare Hare Barn with her husband, Eric. Over several decades, she has learned to manage all sorts of livestock in all sorts of weather conditions at her Kansas home.