Calves that get chilled at birth, without immediate assistance to warm and dry them and haven’t ingested colostrum in a timely manner, have poor survival rates.
If a calf gets cold before it suckles, it won’t be able to get the teat in its mouth. If it fails to nurse, it doesn’t get the crucial energy (for keeping warm) or the antibodies it needs to protect it against disease. Also, its ability to absorb antibodies from colostrum diminishes as it becomes colder. Even if you force-feed it colostrum a few hours after birth, absorption rate will be less than that of a calf that was not chilled.
Late winter storms can put newborn calves at risk even in a spring calving season. Some years, more calves are lost to bad weather during “spring” than during winter calving, because ranchers with spring-calving herds may not be as prepared for dealing with cold stress if they don’t have facilities to provide shelter for newborns.
Russ Daly, extension veterinarian at South Dakota State University, says cold stress in calves may be aggravated by nutritional issues in the cows. If the cow is in poor body condition or doesn’t have adequate protein and energy during late gestation, the newborn calf will have decreased amounts of brown fat for energy reserves and will chill more quickly.
“Protein and energy are crucial, and there’s also research that shows supplying supplemental fat to cows during late gestation will help the calf be better prepared to handle cold weather,” says Daly. “Much of how cows are fed, however, revolves around economics and logistics — how to supply some of the ration ingredients.” Cows that are not protein-deficient will produce better colostrum.
Timely ingestion of colostrum is a big factor in how a calf handles cold weather. A calf that nurses soon after birth stays warmer. The type of fat in colostrum is readily metabolized to keep the calf warm.
“Sometimes this is overlooked,” says Daly. “The rancher might be more focused on getting warming boxes ready for the calves, but colostrum is really crucial. I was involved in a study with Holstein calves in which some did not receive colostrum. When cold weather hit, it was very obvious which calves had colostrum and which ones didn’t. The colostrum contains much higher levels of fat and protein than regular milk.”
After a newborn calf nurses a full feed of colostrum, it can handle the cold.
“It quickly absorbs the lipids (fats) and amino acids, and this aids the body’s physiology and metabolism; the calf doesn’t have to burn so much of his brown fat to keep warm,” says Daly. “Calves most adversely affected by cold stress are ones not able to get up and nurse.”
With these cold calves, producers need to intervene quickly. Force-feeding colostrum can make the difference between survival or not.
If a calf becomes too chilled before it can nurse, it may not absorb antibodies when it is fed. “Any stress,whether from cold, or a difficult birth, can interfere with optimum absorption,” says Daly. “If it’s a question of warming the calf or giving it colostrum first, don’t delay on the colostrum.” Ideally, producers should be able to bring the calf out of the cold and give it colostrum at the same time it’s warming up.
“Calves that have undergone cold stress are more likely to have problems with scours, pneumonia and other infections,” he says. So it is important to prevent cold stress if possible. Paying attention to cows’ nutrition pre-calving is important, along with watching weather forecasts.
“If you know a storm or cold weather is coming, get the calving cows out of the elements, and take care of any calves born outside as quickly as possible,” Daly says. “Newborn calves can handle relatively cold temperatures, with no wind. But if there’s wind or precipitation with the cold, they lose too much body heat from being wet. They need to be dried as soon as possible.
“I’d worry more about a 32 F (zero C) temperature with wind and precipitation than a much colder day with no wind,” says Daly.
A “warm” windy day can be deceptive and producers may not realize drying a newborn calf is an emergency. Even though the temperature isn’t very cold, the wind or precipitation may chill it too quickly, making it impossible for it to get up and nurse before it’s too cold.
“You can tell when calves are really cold, and you can usually tell when calves will be all right, but it’s those borderline calves that may be hard to determine,” he says. “Many ranchers will stick a finger in a calf’s mouth to see how cold it is (if a calf hasn’t nursed yet, the inside of its mouth is usually cold, for instance), but I encourage producers to use a rectal thermometer. Any calf whose rectal temperature is below 100 F (37.7 C) could benefit from being warmed or having a supplemental dose of colostrum.”
If producers aren’t sure how much or whether a calf has nursed, feed it colostrum.
WARMING A CALF
Daly says there are many options for calf-warming boxes, including commercial boxes which blow warm air from the bottom. These quickly help warm the calf body, as well as the air it breathes.
“A commercial warming box may be more expensive, but often these are made from a poly type of plastic, which is very easy to clean,” says Daly. Producers can also build adequate wooden warming boxes, and they work very well to insulate the calves, but they are a lot harder to completely clean. Boxes should be cleaned and disinfected between calves.
“Bacteria love a nice warm place with humidity,” he says. “I’ve seen several situations in which suspected poor sanitation in the warming box led to an increase in calf scours. Paying attention to materials and design, and making sure the box can be cleaned easily, is important. You need good ventilation in the box, and some way to remove humidity. If it’s too humid, you have more problems with respiratory diseases in the calves as well as a buildup of pathogens in that environment.”
In cases of frostbite, rub the calf down with warm water, if it hasn’t been cold too long. “The key is warm water, not hot,” says Daly. “This can help warm the tissues, but you don’t want to rub very much because those tissues may be damaged from freezing and you could damage them worse.
“Purebred breeders are very diligent to prevent frostbitten ears and tails, for cosmetic reasons. There are various types of ear warmers that you can buy. Even commercial cattlemen usually try to keep calves from losing ears and tails, because it is a well-being issue. They don’t want the calf to suffer pain.” Also, a calf without ears or tail is less able to protect itself from flies.
Frozen feet is a more crucial issue.
“Most of the calves I’ve seen with frozen feet were usually debilitated from some other reason, like scours,” says Daly. The dehydrated calf has less blood flow to the extremities; its limbs become cold and more vulnerable to freezing. A sick calf spends too much time lying down; it may not be able to and walk and get circulation going. Blood perfusion to the limbs is severely compromised and a rancher may not realize that these calves may freeze their feet at temperatures that would not be dangerous to a normal, healthy calf. †