Cold stress:Impacts from cold weather affect cattleWritten by Natasha Wheeler
As winter moves into the region, Dan Thomson and Chris Reinhart from the department of animal sciences at Kansas State University discuss management practices to reduce cold stress in cattle, noting that there are a number of factors to consider in evaluating cold weather, particularly as it relates to calves.
“A lot of times, we calve when there is still snow on the ground, and we can get cold stress in those baby calves,” comments Thomson.
Using a rectal thermometer is one way to determine the body temperature of newborn calves, which should be warmer than 100 degrees Fahrenheit.
“If those calves are less than 100 degrees, they are in mild hypothermia. If they are below 94 degrees, that’s when we get into severe hypothermia, and that’s when we have to warm those calves up,” he continues.
Thomson suggests three different methods for warming up calves, including water baths, heating blankets and heat boxes.
“If we are going to run a water bath, we have to make sure to prop the calf’s head up so he doesn’t drown, and we want the water temperature to be about 100 degrees,” he notes.
Water baths should be out in the calving barn and used only for animals to prevent the spread of zoonotic diseases.
“We had a young child die when a calf was put into a bathtub to warm up. The calf had Salmonella, and the young child took a bath the next night, drank some of the water and got a multi-drug-resistant Salmonella,” Thomson laments.
Warming blankets can also be used to treat cold-stress in calves, but producers should be cautious with blankets that can get too hot and burn the animals.
“If we us a hotbox or heat box, we want to keep that box at about 105 degrees and make sure it has good ventilation,” Thomson adds.
Boxes without proper ventilation can develop hot pockets and be dangerous for the calves.
“Also, we need to clean out the boxes between calves so we don’t have diarrhea or other diseases passed between calves,” he comments.
It's also important to make sure that the animals receive colostrum as soon as possible, while they are being warmed or shortly after.
“The key to neonates, whether it’s a puppy, a kitten or a calf – when it comes to cold stress, fluids and warmth are the two major things,” he explains.
Reinhardt adds that preparation is critical, because it is much harder to manage cold stress than to prevent it.
In a feedlot situation, water and mud are important factors to consider when temperatures begin to drop.
“It’s easy to forget how important mud is in this problem,” he says. “If we have wet pen conditions, it doesn’t have to be that cold to really put the hammer down on feeder cattle.”
Building dirt mounds within the pens is one suggestion presented by Reinhardt, so that cattle have a relatively warm and dry place to lie down if it does rain or snow.
“Cattle will use the side of the mound opposite of the wind as a sort of windbreak as well,” he adds.
Thomson notes that the mounds need to be big enough to accommodate all of the cattle in the pen.
“The ones who don’t get on the mound are probably the ones who need it most. The smaller and weaker calves are the ones who get pushed off of the bunks and off of the mound, so we need to make sure we build the mound big enough,” he says.
Windbreaks are also important in cold, windy weather, and Reinhardt explains that the breaks should not be solid.
“If we have a continuous windbreak, it’s going to be a really good snow accumulator. Having some gaps in the windbreak and allowing snow to move through will give the cattle some protection from the wind,” he comments.
It’s also important to make sure that the breaks are both wide enough and tall enough to provide enough shelter for all of the animals in the pen.
“Windbreaks are great in the winter, but in July and August, they can mean real problems for feedlot cattle,” Reinhardt adds.
On hot days, a breeze helps to keep cattle cool. Removable windbreaks may be appropriate in areas that get hot temperatures in summer months.
Thomson notes that mature cows can also be affected by cold stress, and it’s important to consider the condition of their hair coat when cold weather moves in.
The lower critical temperature of an animal is the temperature at which cows begin to experience cold stress. Cows with a slick summer coat can experience a lower critical temperature at 59 degrees.
“If they have a fall hair coat, we are taking about 45 degrees, and as the hair gets heavier, 32 degrees is the lower critical temperature for a winter coat,” Reinhardt says.
Northern-bred cattle with deep winter coats can go down to 18 degrees or below for a lower critical temperature.
Reinhardt also comments that animals experiencing cold temperatures may need extra feed to maintain body condition.
“Cows will lose body condition to meet the added demand for energy, and we won’t see it for a period of weeks or even months,” he explains. “When we get a cold snap, we know we have to increase the energy available to those cows.”
Thomson adds that the cold months often coincide with the third trimester or lactation as well, depending on spring or fall calving. This also adds an extra energy requirement for the maintenance of cow body condition.
Concluding their recommendations, Thomson notes, “When we think about these critical management decisions, we should work with our local veterinarian and our nutritionist.”