Raising calves during colder weather presents several challenges that require increased attention to your calf care program. The primary reason that we discuss cold weather implications for calves, but not for older dairy animals, is that they are uniquely different. Because of their smaller body size, there is a greater surface area to body mass ratio making them more susceptible to heat loss through several processes. This loss of heat causes the calf to expend more of her energy maintaining core body temperature and reduces her rate of growth, or in extreme conditions causes her to lose weight.
Providing a dry, well ventilated, and draft free environment should be the primary consideration during cold weather. If available facilities are not sufficient, calf blankets have been marketed as a management tool for raising calves in colder weather. Blankets serve as a buffer between the calf and adverse conditions in their environment including moisture, cold temperatures, and wind. Research conducted at North Dakota State University found that in cold weather, blanketed calves gained 1.35 lbs. daily compared to just 1.06 pounds for their un-blanketed herd mates during the first 21 days of life. Researchers also noted that the advantages in rate of gain diminished over time.
The greatest benefit from blankets came during periods of severe winter weather. Blankets are also recommended to be used when temperatures were below freezing. The advantages of blankets become marginal when daily temperatures rise enough to cause the animal to sweat, then to lose body heat evaporating that moisture during the cooler night period. The research found that the improvement in rate of gain diminished after 28 days of life. This coincides with the age when many calves are consuming enough starter to have good rumen function, which produces a considerable amount of heat. Additionally, the consumption of starter feed provided additional energy for maintenance and growth.
In summary, blankets can be a useful tool in managing calves during winter weather. Primary consideration should still be given to providing a dry and draft free environment and ensuring that calves receive enough nutrients through starter and milk replacers. Blankets are likely to be the most beneficial for young calves that are not yet eating ample starter during extended cold spells.
Dairy Pipeline: John Welsh, Extension Agent, Virginia Cooperative Extension