Cold stress can increase the risk of disease in pre-weaned calves. Additionally, growth rates can decrease during the cold months unless enough energy is provided through a higher plane of nutrition or energy is preserved by improving the environment, said Jackie McCarville, University of Wisconsin Extension dairy educator.

A calf is born with only 2 to 4% of body weight as fat, McCarville said in an Extension news release. If forced to burn fat to maintain body temperature, calves will typically have lower growth rates or compromised immune status.

If not managed well, death rates in calves are greater during cold weather.

Older calves can tolerate colder temperatures more than calves who are less than one month old can. The lower critical temperature in a calf less than one month of age is 48 degrees Fahrenheit versus 32 degrees for an older calf. When temperatures decrease to less than the lower critical temperature, calves will begin to use more energy to maintain their core body temperature and less energy to support growth and the immune system.

Younger calves have more surface area and weigh less than the older calves, causing them to lose body heat quicker.

Wet calves are susceptible to frost bite, so during the winter months they need to be dried off quickly after birth. Once calves are dry, producers need to quickly warm the calves. Blankets or warming boxes can aid in warming a newborn. Ensure the calf area is draft free and has a deep bedding pack, such as straw, which can help ensure they don’t lose too much body heat once warmed.

When the temperature decreases, producers want to ensure calves have sufficient deep, clean and dry bedding to allow for nesting behavior. Calves should have a nesting score of 3, which means their legs are completely covered by the bedding and not seen.

Bedding provides a cushion from the ground, separating the calf from the cold ground and any moisture that has seeped through the bedding. Using bedding such as straw is recommended during the winter months because it helps reduce heat loss by conduction that would occur with sand bedding.

Utilizing calf jackets can be a great tool for helping with cold weather. However, producers must ensure the jackets are dry and cleaned between uses. In warm stretches of weather, monitor calves for sweating under the jacket. Jackets might need to be removed during the day and put back on at night.

Adjustments might need to be made to jackets as the calf grows. Ensure the jacket isn’t rubbing against the skin and causing raw spots.

A general rule of thumb is to use a calf jacket when the ground is frozen and the calf is less than 21 days old.

Just like in the summer, producers need to provide calves with water. During the winter months be sure the water is warm. It should be close to the calf’s body temperature so the calf doesn’t need to burn energy to warm the water to body temperature and so water sources do not freeze.

Additional milk and calf starter may be needed when temperatures decrease to less than the calf’s thermoneutral zone. Calves less than three weeks of age typically don’t eat much starter. Therefore considerations should be made to increase calories through increased volume of milk at each feeding or through an additional feeding during the day.

Increase milk-replacer powder based on manufacturing recommendations in order not to cause gastrointestinal issues due to too much concentration of solids or addition of supplemental fat.

If using indoor housing, ensure it provides some ventilation. Temperatures shouldn’t fluctuate more than 5 degrees in a temperature-controlled building. Often respiratory issues increase during the winter months if indoor housing doesn’t allow adequate air exchange.

If using hutches outdoors, be sure they are in a well-drained area and the wind isn’t blowing directly into the front of the hutches. A windbreak can be used to reduce the wind chill on calves if the wind direction is frequently an issue.