Keeping calves cool: how to manage heat stress in young dairy cattle

Just like dairy cows, calves are vulnerable to heat stress, especially during the summer months. Managing calf comfort during hot weather is essential for maintaining calf health, supporting growth, and improving future dairy herd productivity.

Effective heat stress management for calves includes proper housing, ventilation, hydration, feeding strategies, and nutritional support.

Young calves have a narrower thermoneutral zone than adult cows. Research shows that a calf’s upper comfort limit is around 29°C, while heat stress can occur above 32°C at 60% humidity (Neuwirth et al., 1979; Gebremedhin et al., 1981).

Reducing heat load in calf housing is therefore critical during warm weather.

For calves housed in outdoor hutches, providing shade is one of the most effective ways to reduce heat stress. Simply placing calf hutches in shaded areas can significantly lower hutch temperatures and reduce calf respiration rates (figure 1).

The impact of shade

Good airflow is essential to keep calves cool during periods of high temperature.

For calf hutches equipped with vent openings, make sure these are fully utilized to improve air circulation. In hutches without vents, raising the back of the hutch can help increase airflow, reduce internal temperatures, and improve air quality.

In calf barns, fans should be positioned to ensure airflow reaches calf level effectively.

Proper ventilation and cooling not only help regulate body temperature but can also improve feed intake, growth performance, and feed efficiency in young calves.

Bedding material also influences calf comfort during hot weather.

While straw bedding provides insulation during winter, it can retain excessive heat during summer months. Switching to wood shavings in warm weather can help reduce heat retention inside the calf housing environment.

Using wood shavings or sand may also help reduce fly pressure, as straw bedding generally attracts more flies.

Heat stress typically reduces feed intake in calves, particularly during the transition from milk feeding to solid feed intake.

Cooling calves during summer can help maintain starter intake and support growth performance. This is especially important during weaning, as rumen fermentation of calf starter and roughage creates additional internal heat production.

Extending the weaning period during summer may help support both rumen development and overall calf growth.

Providing sufficient clean drinking water is critical during periods of heat stress.

Research shows that when temperatures increase from 10°C to 30°C, water intake in calves can double due to increased respiration and sweating. Increased panting during heat stress may also elevate the risk of metabolic acidosis.

To support calves during periods of high temperature, additional water supplemented with electrolytes and dextrose can be beneficial.

Offering an extra feeding of water with electrolytes between milk feedings helps maintain hydration, supports electrolyte balance, and may reduce the risk of metabolic acidosis during heat stress.

Average water intake of calves between the age 5-56 days in relation to temperature

Managing heat stress in calves is not only important for immediate calf welfare and performance, but also for the long-term success of the dairy operation.

By adapting calf management practices during hot weather, dairy producers can support healthy growth, improve development, and build the foundation for a productive future dairy herd.