For the most part, the calves being born this time of the year are dairy calves. That being said, a cold and wet March can affect the beef producers as much or more as a cold, snowy January.
Calves, like us, would prefer to be warm and dry during the winter. If they can’t be both warm and dry, at least do your best to keep them dry and out of the wind. Studies and experience have shown that calves that are protected from the wind can endure outside temperatures of -20 degrees reasonably well for small periods of time.
The flipside of that equation, however, is that calves exposed to 30-mph winds or greater can become hypothermic, even if the thermometer reads 20 degrees.
Ventilation and pen design (whether pen refers to group or individual housing) must be considered year-around, but it is often overlooked during the winter. Our instincts, with the best interests of the calves in mind, typically cause us to under-ventilate in cold weather. This leads to stale, humid air, full of airborne bacteria and viruses, and increased levels of ammonia which irritates the calves respiratory tract and decreases the immune response of a calf. Minimum ventilation rates, when set up properly, allow for adequate fresh air and air movement without chilling calves.
Bottle calves that are housed outside in hutches, poly-domes, or something similar, require special attention as temperatures hang around zero. Though consistently cold temperatures may be better for calf health than the ups and downs you often see in fall and winter, they are not ideal for efficient growth.
For calves less than three weeks old, every degree below 56 degrees requires additional energy just to live. For calves three weeks old through weaning, that number is 33 degrees. Obviously, producers expect their calves to do more than just live. Typically, it takes an extra 1/2 pound of a 20/20 milk replacer for calves to gain one pound per day in cold weather. This equates to roughly 50 percent more milk replacer during the winter than during the spring and fall.
When temperatures really get down there, feeding the smaller calves an additional feeding of electrolytes keeps them active and their appetites healthy. As long as the electrolytes are fed at least an hour after milk or milk replacer is fed, the full benefit of the extra energy can be utilized.
Bedding is another important consideration during cold weather. The choice of bedding material and amount of bedding both play a role. Sure, it stands to reason the deeper and “fluffier” bedding improves calf comfort in the winter, but bedding is expensive, and keeping up with it is labor intensive. How much bedding is enough?
Bedding, or “nesting” scores have been a useful tool to evaluate the amount of bedding in a calf pen. A score of 3 (calf feet/legs aren’t visible when the calf is lying down) is desired from November – April. A score of 2 (legs partially visible) may be adequate for older calves, but not for young, small calves.
Regardless of age, a score of 1 (calf lying on top of the bedding with feet and legs fully visible) will result in chilled calves and most likely, an increase in sickness. Calf blankets help calves to retain body heat, and may help block some wind. As a rule of thumb, a good calf blanket increases the nesting score by one (from a 1 to a 2, or a 2 to a 3).
Quickly, on the subject of calves and electrolytes, I want to address winter calf diarrhea. What might be a moderate case of diarrhea during milder temperatures can quickly become life-threatening during winter.
From what we’ve already discussed as far as extra energy needs during cold weather, it should come as no surprise that any nutrient loss associated with diarrhea cannot be tolerated by small calves. The directions on many electrolyte products will instruct you to feed their product twice a day for two days, and withhold milk or milk replacer during that time.
During periods of cold weather, there is not enough energy in the electrolyte products to allow a calf to survive and grow. Recent studies have shown that calves that are fed milk replacer twice a day, with two additional feedings of electrolytes, recover just as quickly from scours and do not suffer any growth setbacks. The electrolyte products lack the fat and protein that milk and milk replacers contain, which are an excellent source of energy for a small calf.
Trying to keep all of this information straight can be confusing and, at times, counter-intuitive. We’re happy to answer any questions that you may have, and will work with your farm’s specific demands to help you optimize calf health during cold weather.