By Dayna Locitzer, DVM
Last issue we talked about the basics of calf care. I think this is a great follow-up question on the quest to take the best care of our calves, especially as we get into the coldest months of the year. In previous issues I have talked about the thermoneutral zone (TNZ) of cows related to heat stress (and how my personal zone is similar to cows). Adult cows have a TNZ of about 32-70 degrees and are quite cold tolerant. Pre-weaned calves have a TNZ of 50-77 degrees. Once the temperature is below 50 degrees, calves will need to expend extra energy to keep their vital functions working properly. It is important to keep this fact in mind in how you prepare for calf care in the winter months. Knowing that calves are less cold tolerant than cows, there are some basic additions to their care.
When a calf is born in very cold weather, it is very dangerous for that calf. While you might want to let the cow clean off her calf, you also want to make sure the calf is dried off quickly. When the temperature is below their TNZ, the calf should be indoors, dried off by a towel, and a calf jacket applied. If it is below freezing, you might need to wipe off the navel dip so it doesn’t freeze and create a frostbitten umbilical cord. The navel dip only needs to contact the skin for 5 minutes to do its antibacterial work. Making sure the newborn calf is dry and warm will prevent frostbite and help their immune system make the best use of colostrum.
During the first three weeks of life, calves are not good at thermoregulation. This means they are a little more amphibian like than your typical mammal. The outside temperature will have more effect on their internal body temperature than an older animal. In the cold months calf jackets become a useful tool. When you feel like you need a jacket outside, the young calf likely does too. A good rubric to go by is the “90 degree rule”, meaning that if the combined high and low temperatures for 24 hours does not exceed 90 degree, then the calf needs a jacket. For example, if the calf is under three weeks old and the daytime high is 50 degrees and the nighttime low is 30 degrees, she needs a jacket. Make sure the calf and the jacket are dry and make sure the jacket fits properly. Improper use of this tool will be more trouble than help.
Because calves will need to expend more energy to keep themselves warm during the winter time, they will need more energy inputs. Pre-weaned calves can get more milk in the colder months. You can give them an extra meal of 2-4 quarts or provide them with 1-2 quarts extra at each meal. Milk should always be fed at a temperature of about 100-105 degrees, an especially important point at this time of year. At this temperature the calf does not have to expend any extra energy warming the milk inside her body.
Speaking of warm liquids, you should provide the calf with warm water at least twice daily. Pre-weaned calves should always be provided with potable water meaning it should be clean and not frozen. A good way to ensure the calf has some time to drink water before it freezes is by providing her with warm water directly after milk feeding when she is in a liquid drinking mindset. If you bucket feed your calves, the water can go directly into the bucket. If you bottle feed them or use a mob feeder, you can put some of the water in the bottle or feeder and satisfy her urge to suckle at the same time! Providing them with small amounts of warm water multiple times a day will encourage drinking and prevent you from having to defrost frozen calf buckets.
Respiratory disease can also be an issue in the winter months. This is true for a number of reasons. Their immune system is taxed from using extra energy to keep themselves warm (so feed them that extra milk!), especially when there are extreme temperature swings. Another wintertime respiratory disease risk factor is poor ventilation. If calves are indoors and barn windows/curtains are closed for warmth, there is a risk for poorer air quality unless ventilation is accounted for. With these increased risk factors, it is wise to make sure the calves are vaccinated. The best vaccine for young pre-weaned calves is an intranasal vaccine. Consult with your veterinarian about which one is best for your farm.
Extra bedding can also help with those cold temperatures. Extra bedding that is clean and dry is very important during these winter months. A hefty amount of straw provides excellent insulation. Providing ample bedding and using calf jackets makes it possible to deliver appropriate ventilation when it is cold outside.
Ok, but what happens if your calf does get too cold? You might see her shivering, hunched and standing in the corner with no other signs of disease. Or she might have been born outside on a cold rainy day. Make sure the calf is dry, has a dry jacket on, and her pen is filled with deep bedding. If she is wet, you could use a hairdryer to dry her off and warm her up at the same time. While I am not a fan of the latest internet craze of bringing your cows inside your kitchen, a hypothermic sick calf might benefit from some time next to the wood stove or at least a heated area of the farm. There are also calf warmer boxes that you can buy. They might be a little pricey, but one saved animal will pay for the warmer with the current market price for calves. Doing whatever you can to dry them off and keep them warm is crucial. Leaving them wet and cold puts them at high risk of frostbite and other illnesses.
As we enter the deep dark months of winter keep in mind these strategies to keep your calves healthy during cold weather. A little babying of your calves will help them grow to become strong and resilient cows. Keep them warm, keep them dry and fill their bellies.
Posted: to Organic Production on Sun, Jan 12, 2025
Updated: Sun, Jan 12, 2025