Keeping Calves Cool Through the Summer Heat – Augusta Hagen

We’ve had a moderately cool summer, but we all know that has abruptly changed this last week. Hot days and humidity make for lots of uncomfortable, low-producing cows.

To cope in our dairy barns, we have implemented innovative cooling systems to keep our cows comfortable, but what about our calves? Are they suffering from the high heat and humidity? Unlike milk-producing cows, calves won’t show their heat stress through low milk, which means we need to keep an extra good eye on them in times of high heat and humidity.

Calves typically perform best when they are within their thermal neutral zone of 55 to 78 degrees F. When the temperature is outside of that zone, the calf requires more energy for maintenance to sustain average daily gain.  This is intuitive in the winter, but it is also true for summer.

The University of Minnesota suggests that calves need an additional 20 to 30 percent more hydration and nutrition in times of heat stress.  So how do we know if our calves are experiencing heat stress and what do we do as caretakers to comfort them?

When calves are heat-stressed, they may not be as excited to eat and need a little motivation to get up and go to the bottle or bucket. When they do get up to eat, they likely won’t finish their meals.  Think of your own eating habits; when you’re hot, the last thing you want to do is eat a big, hot meal quickly. Rapid respiration and lethargy are a few other signs of heat stress, along with decreased consumption of milk, water and grain.

So how can we limit the effects of heat stress on calves? First and foremost, prevent dehydration through adequate water intake.  As we said, this can be difficult when calves are not motivated to eat.  Do you best by making sure the calves always have access to fresh, free-choice water.  This might mean an extra water feeding (or two or three) throughout the day.

Next, provide adequate airflow, which can be adjusted in an indoor calf barn, but is out of our control in outside hutches. Be sure to go through your ventilation program when it is hot to make sure the calves are getting enough fresh air indoors. If the calves are outside in hutches, possibly put a shade up over the hutches if the calves are in direct sunlight with no shade.

Here are some other simple things you can do when it’s hot:

• Offer another feeding of fresh water during the hottest time of the day to promote water intake.
• Offer electrolytes a few hours after milk feeding if the calf wasn’t willing to finish its milk (or was slow to finish) to improve hydration status.
• Freshen the grain daily to increase starter intake and keep the starter from drying out as fast, especially if it is exposed to direct sunlight in a hutch system.
• Don’t increase the calf’s stress load by moving or vaccinating during the hottest parts of the day. If you must perform these tasks, do them early in the morning when it’s the coolest part of the day and the calves have had the night to cool down as well.
• Implement proper fly control programs to decrease fly stress on the calf.
• Look at the bedding.  Regardless of whether it’s sand or straw, make sure it’s dry and clean.

We all get a little uncomfortable in these high temperatures and that’s true for our cows and calves too.  Do your best to limit stress as much as possible.  Finally, remember to take care of yourself and your team too by staying hydrated and allowing for plenty of time to rest.