A calf jacket can help a newborn stay warm when winter temperatures drop. But if calves are shivering, lying in damp bedding or breathing stale barn air, a jacket alone won’t protect their health or keep growth on track.
“Calves are more likely to die from pneumonia before they die from the cold,” says Bethany Dado-Senn, calf and heifer consultant and herd manager at her family’s dairy in northwestern Wisconsin. “Keeping calves comfortable doesn’t mean we need to sacrifice ventilation.”
Cold weather also forces calves to use more energy to stay warm, leaving less available for growth. Dado-Senn recommends helping calves retain body heat before increasing their energy intake through milk.
“I want to talk about reducing the energy that is sent out first because that is far and away our more economical approach,” she says. “Bringing energy in, energy costs dollars.”
The first step is recognizing signs of cold stress and addressing conditions in the calf’s environment, including bedding and ventilation.
Watch Calf Behavior
For young calves, the lower critical temperature is around 50°F. This is the temperature below which a calf must use additional energy to maintain her body temperature. As temperatures fall below this threshold, more of the energy a calf consumes goes toward staying warm rather than growth.
Shivering, huddling, a hunched posture and avoiding drafts can signal cold stress. Producers should also watch how calves position themselves when resting and whether they appear comfortable in their bedding.
“Behavior is first and foremost my first round of detection,” Dado-Senn says.
As temperatures fall, calves may increase feed intake to meet their higher energy needs. Changes in feeding behavior, along with signs such as shivering or huddling, can help producers identify calves struggling with the cold. Catching those signs early gives producers a chance to address bedding, drafts or nutrition before cold stress affects calf health and growth.
Build a Better Bedding Pack
Bedding helps calves conserve body heat by insulating them from cold surfaces and giving them a dry place to lie down. Dado-Senn recommends a deep straw pack to help calves stay warm, especially when temperatures fall below their lower critical temperature.
She recommends a base of 3 to 4 inches of wood shavings topped with roughly 12 inches of straw. Producers can assess bedding with a nesting score from zero to three. At a score of three, a calf’s legs are no longer visible when she lies down.
Straw gets packed down over time, so bedding needs regular attention. Dado-Senn says adding straw daily can help maintain nesting depth, while calf jackets offer another way to conserve body heat.
Sand is less suited to winter conditions because it does not insulate like straw.
“Sand is great for the summer because it is non-insulative,” Dado-Senn says. “But when it comes to the winter weather, it’s not my first choice.”
Use Jackets and Keep Air Moving
Bedding helps calves hold body heat from below, while calf jackets provide another layer of insulation. But keeping calves warm doesn’t mean shutting out fresh air. Dado-Senn recommends using the “rule of 90” to help determine when calves need jackets. Add the daily high and low temperatures; when the total falls below 90, jackets may be beneficial.
She tested wool, canvas and quilted jackets in a small, informal comparison, using warm water in a balloon to compare heat retention. The styles performed similarly in her test.
“I usually stay in the camp of whatever works best for your system in terms of which blanket to try,” she says.
Dado-Senn generally recommends jackets during the first three weeks of life and removing them a couple of weeks before weaning.
“We want to have that calf learn how to thermoregulate on her own,” she says.
Jackets and deep bedding do not replace ventilation. Dado-Senn recommends targeting four to six air exchanges per hour while keeping air speed at calf level below about 0.5 mph. Smoke testing can help identify drafts and areas where fresh air is not moving effectively.
Winter concern about cold temperatures can lead producers to close up calf barns too tightly.
“I am constantly trying to convince farms that it’s going to be okay,” she says.
Dado-Senn recalls working with a farm where ventilation tubes shut off at 30°F, even though the system needed to keep bringing in fresh air.
“Air exchange and preventing pneumonia is more important than keeping calves a little bit more buttoned up,” she says.
Adjust Milk Feeding
When temperatures fall, calves need more energy to maintain body temperature. Producers can consider increasing milk volume or adjusting solids, depending on their feeding program.
Milk should be fed at about 105°F. Cold milk replacer powder can lower mixing water temperature, even when the powder is stored at room temperature.
“Even room temperature milk replacer drops your water temperature by about 5°,” Dado-Senn says. “So we do want to increase our water temperature a little bit in the winter months per mixing.”
She suggests considering an additional half-quart of milk per feeding or increasing milk solids by half a percentage point. Producers should follow their feeding program and avoid mixing milk replacer too heavily, which can create digestive problems.
Warm drinking water and fresh starter also support intake. Dado-Senn points to a general relationship of about 3 pounds of water consumed for every pound of starter eaten.
Prepare for Colder Newborns
Newborn calves need to be dried promptly and moved to a warm, dry resting area. Colostrum should be fed at about 105°F, though Dado-Senn says producers can warm it to 115°F or 120°F before feeding in colder conditions. Avoid temperatures above 140°F, which can damage immunoglobulins.
Winter also can bring a seasonal decline in colostrum supply. Dado-Senn describes a “colostrum slump” in December and January, when production may fall by 1 to 2 quarts per cow.
“Now is the time of year to be storing up any sort of extra first or second milking that you are getting,” she says.
She recommends testing stored colostrum with a Brix refractometer, aiming for a reading above about 24%. Colostrum can be stored for around eight months while maintaining immunoglobulin levels, she says.
Dado-Senn also cautions producers not to rely too heavily on replacer as winter approaches. Supplies can be tight, making it worthwhile to build a reserve of quality maternal colostrum.
Track Seasonal Performance
Winter does not affect every calf program the same way. Dado-Senn says calves in the Midwest may grow better in winter because they experience less heat stress and eat more starter.
“Calves often grow a little better in the winter because they aren’t dealing with heat stress, which can limit how much they eat,” she says.
Even in the coldest months, small details in daily care can make a difference. Dry bedding, a warm place to rest and enough energy to keep growing help calves stay comfortable through winter. With the right care, they can continue building a healthy start, even when temperatures drop.
