Helping cows cope with cold stress
Published on Jan. 11, 2020
“The first and most important thing to recognize is cold stress increases the energy requirements of cattle and thus can very easily decrease body condition and fat stores,” states Nebraska Extension Beef Systems Specialist Dr. Mary Drewnoski during the Nov. 6 episode of the University of Nebraska-Lincoln’s (UNL) BeefWatch podcast.
“How cattle fare during the winter months affects calving success and rebreeding success. Therefore, it is extremely important to set them up for success early in the winter,” she continues. “Getting cows up in body condition score early in the winter can also be a risk management strategy to ensure they can handle cold stress later in the winter.”
BCS and lower critical temperature
Drewnoski explains lower critical temperature is the temperature at which cattle have to start using their energy stores to maintain their body temperature and says this is affected by the cow’s body condition score (BCS).
“Cows with a little more flesh, and therefore a higher BCS, will have a lower critical temperature, meaning they can handle lower temperatures without having to use their energy stores to maintain their body temperature,” Drewnoski says.
She continues, “On the other hand, cows with poor condition early on are going to be in very poor condition later in the season because they have a higher lower critical temperature.”
Other factors affecting cold stress
Drewnoski explains wind chill and wet hair coat are two other factors that may have an impact on cold stress in cattle.
“Cows aren’t dumb,” Drewnsoki states. “If they have a place to hunker down and get out of the wind they will.”
Because of this, Drewnoski says it is important to provide cattle with some type of windbreak.
“A 10 mile per hour wind can make it feel 10 degrees colder, which requires a significantly larger amount of energy for cattle to maintain body temperature,” she says. “If cattle are out in a flat field with no shelter, putting a windbreak out is one of the easiest ways to help cattle deal with cold stress.”
Drewnoski explains wet hair coat can also have a huge impact on lower critical temperature. However, besides providing cattle with shelter or more energy, Drewnoski recognizes this isn’t something producers have much control over.
“A wet hair coat is a whole different situation,” Drewnoski explains. “If a cow has a BCS of five and she has a dry hair coat, her lower critical temperature is 19 degrees, meaning until wind chill temperatures are below 19 she can maintain her body temperature without any extra energy.”
She continues, “On the flip side, if the cow has a wet hair coat, her lower critical temperature is 50 degrees.”
Coping with cold stress
Drewnoski notes sometimes cattle can’t eat enough to maintain their condition. In situations where this might be the case, she suggests a few different options.
“If cold stress is mild, producers can simply feed a higher quality forage, if this is possible,” she says.
According to Drewnoski, another option is supplementation. She says when it comes to energy supplements there are two things most people think of – corn and distiller’s grains.
“Corn is a fairly cheap energy supplement, but the challenge with corn is if we feed to much of it, it will negatively impact forage digestion and reduce the amount of energy cattle get out of forage,” Drewnoski explains. “As a rule of thumb, don’t feed more than two pounds of corn.”
Drewnoski notes in cases of extreme cold stress, feeding two pounds of supplemental corn won’t cut it.
“Therefore, another option producers should consider is feeding supplemental distiller’s grains. Distiller’s grains are not only a great protein supplement, they are also a good source of energy,” she explains. “The benefit of distiller’s grains is they have more energy than corn and they don’t have a negative effect on fiber digestion.”
Hannah Bugas is the assistant editor for the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.
