The new year may have entered like a lamb, but February rolled in like a lion.  For those that calve in January and February, the rapid changes in temperature may have played a role in calf sickness and growth.  Maintaining a healthy calf is crucial to growth and a good immune system.

As the temperature drops, cow body heat needs to be maintained, which we can accomplish with extra feed.  Utilizing forages, such as hay, will aid in maintaining body heat during cold temperatures through fermentation within the rumen.  Dropping temperatures also increase nutrient requirements of cows, which may be increased by at least 50% as the temperature drops below zero.

The additional nutrients provided to cows during the winter also has an impact on calf birth weight.  Birth weight of calves born in the winter and spring typically have greater birth weights greater than their fall born counterparts.  The increase in birth weight of those winter and spring born calves is most likely due to the increase in nutrient influx through supplementation.

Bitter cold temperatures not only add stress to the cow, but also the calf.  Calves need to nurse within 2-4 hours after calving to get the maximum benefit of the cow’s colostrum.  This becomes even more important during cold temperatures.  Providing a sheltered, dry area for calving can drastically reduce the negative impacts of cold temperatures on calf health.

Research has indicated that the lower critical temperature for calves is approximately 60°F.  If the calf is not dried off quickly or if it’s raining or snowing, that temperature is about 70°F.  In Montana, we won’t see 60°F temperatures again until March or April.  Even with the bitter cold temperatures, calving can be managed to reduce the stress on the calf and the producer by monitoring the weather forecast, ensuring cows have a sheltered area to calve, and checking that calves are dried off quickly after calving.

A large drop in temperature can cause health issues for calves, but what occurs when there is an upward swing of temperatures or a large variation of temperatures.  A wide swing in temperatures can also be detrimental to calf health.  However, it difficult to adjust when the temperatures are highly variable.  When it’s cold, we can feed additional supplements to cows, which will provide additional nutrients to the calf through the milk.

If we see a rapid warming trend, the best way to ensure calf health is through your calf health program.  The first step is to ensure your cows are on a good health and vaccination program that you have discussed with your veterinarian.  The second step is to ensure your calves consume colostrum within 2-4 hours after birth, the colostrum provides maternal antibodies to calves and passive immunity.  Having your calves on a good vaccination program beginning at birth will ensure good active immunity.  Active and passive immunity will aid calves in maintaining a healthy immune system, especially if we see rapid changes in weather patterns.

Additionally, as temperatures warm, snow melts and the ground thaws, which can cause wet, muddy areas.  Keeping cows and calves out of these areas can reduce the potential for illness.  Keeping cows and calves dry, even if the temperature is not that low, is crucial to maintaining a healthy herd.  Healthy calves have improved growth and tend to be healthier throughout their life compared to calves with compromised immune systems.