Heat Impacts: Producers should monitor livestock for heat stress
Many producers fail to realize that a comfortable temperature for cattle is typically cooler than what is comfortable for us.
As temperatures rise above 75 degrees, cattle can begin to experience heat stress. Signs of heat stress may include animals bunching, seeking shade and panting. In extreme situations, the animals may show slobbering, excessive salvation, open-mouth breathing, foam around the mouth, lack of coordination and trembling.
“In addition to temperature, as the humidity goes up, the affects of heat stress can be greater in cattle,” said Richard Randle, Extension veterinarian with the University of Nebraska.
As cattle heat up, they will increase respirations to get rid of the excess heat. As temperatures continue to climb, they can become even more heat stressed, exhibiting very rapid breathing or even open-mouth breathing in severe situations, Randle explained.
“Their temperatures can rise to 106, 107 or even 108 degrees,” he added.
When producers see these signs, they should take precautions like providing more shade for the cattle, whether it is natural or otherwise.
“If the cattle can gain access to some wind movement, it can have an evaporative cooling effect on them,” he explained.
For cattle in confinement, Randle recommends spraying them with water or misting to get them wet.
“In combination with wind moving over them, it can help them cool down,” he said.
In any situation, producers will want to make sure livestock have access to unlimited clean, fresh water, even if additional tanks must be added.
“Water consumption can triple in terms of the daily water intake cattle need,” he said. “For instance, a 600 to 700 pound animal can triple their water intake up to where they need 20 to 25 gallons of water a day.”
Most of the time, cattle can get some relief at night when temperatures typically cool down below the low 70s, allowing the cattle to dissipate a lot of the heat they absorbed during the day.
“It can be a problem if there are three or four consecutive days, where it stays hot, humid and above 75 degrees at night, to where the cattle can’t dissipate that heat,” Randle explained. “If that happens, the producer needs to find a way to help them dissipate the heat through shade or something like that.”
Cattle are considered incomplete sweaters, Randle continued.
“They can sweat around their nose, but they are not profuse sweaters. Their main way to dissipate heat is through increased respiration. Normally, they breathe 40 to 60 times a minute. If they get up to 80, they are starting to feel the affects of heat stress. If it gets up to 90 or more, they are really suffering,” he said.
If the animal survives severe heat stress, Randle said it typically doesn’t suffer any direct long-term effects. However, if the body temperature gets high enough, it can affect the nervous system and cause convulsions.
“If they survive that, there may be some damage, but it could be hard to find,” he said.
Cows that are in early to mid-gestation could lose a pregnancy if they get too hot, Randle noted. Cattle on feed typically reduce feed intake, which affects weight gains, and dairy cattle will have reduced milk production.
“Producers may have to adjust the diet of these animals to offset the affects of heat stress,” Randle said.
Although any animal can suffer from heat stress, black-hided cattle are particularly vulnerable because they will absorb more ultraviolet rays. Some breeds, particularly those with Brahma influence, can be more tolerant to the heat.
Animals in confinement can have heavier heat loads than those on pasture because of less air movement and shade. They can also be exposed to more radiant heat from concrete and dark, bare soil. Livestock that are heavier or have a higher body condition score are also more prone than light animals or those with a lower body condition score.
Randle said it is important for producers to realize that cattle can express symptoms of heat stress at lower temperatures than they might expect.
“It is a matter of close watching and observing,” he said. “Providing plenty of fresh water and shade are critically important. Fortunately, it typically cools off at night, and normally, we do not have extended periods of heat.”