Calves begin to burn energy to maintain their core body temperature when the outside temperature falls below 60 F. That’s why it’s so important to feed liquids at the calf’s body temperature — about 102 F — during cold weather, says Sam Leadley, a calf-management specialist with Attica (N.Y.) Veterinary Associates.
Here’s a handy trick to help you keep milk or milk replacer at 102 F during cold weather: Simply place three or four 2-quart calf bottles of milk in a clean 5-gallon pail. Then, fill the pail with 130 F to 140 F water to keep the bottles warm. You’ll have to experiment with how much water to add. “At 40 F, not much is needed. At 10 F, I always have to fill the pail nearly full,” Leadley says.
This practice also works when you train calves to use a pail. Simply leave the bottle in hot water while you train one calf. When you’re done, pour the warm bottle of milk into a clean pail for the next calf.