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. Ensuring their comfort and well-being is essential for their growth and future productivity.

The comfortable thermoneutral zone for young calves is narrower than for adult cows. A calf’s upper comfort limit is about 29°C with heat stress considered above 32°C with 60% humidity (Neuwirth et al., 1979; Gebremedhin et al., 1981).

For calves housed in outdoor hutches, shade is the first step to prevent high temperatures in the hutches. Simply putting the hutches in the shade already has a big impact on the tem­perature and eventual respiration rate of the calves (Figure 1).

The impact of shade

To keep calves cool in high temperatures, enhance air circulation. For hutches with vent openings, utilize them to boost airflow. In hutches lacking vents, elevate the back of the hutch to improve airflow, lower temperature, and enhance air quality (Figure 2). In barns, use fans to circulate air effectively, ensuring it reaches calf level. Cooling calves not only regulates temperature but also enhances intake, growth, and feed efficiency.

To reduce heat stress, consider changing bedding materials. While straw is ideal for warmth in winter, it retains heat in summer. Switching to wood shavings during summer helps lower heat retention. This change also reduces fly pressure in housing, as straw tends to attract more flies compared to sand or wood shavings.

Hot weather reduces feed intake, particularly in calves transitioning from milk to solid feed. Cooling calves boosts feed intake, especially during weaning when rumen fermentation of starter feed and roughage generates an additional heat load. Extending the weaning period in summer is advisable, as it supports calf growth and rumen development.

Water is crucial for calves, especially in summer. As temperatures rise from 10°C to 30°C, water intake doubles due to increased sweating and respiration. Don’t forget that increased panting in heat raises the risk of metabolic acidosis.

To support calves during high temperatures, provide additional water with electrolytes and dextrose. Feeding calves an extra meal of water with electrolytes between milk feedings ensures adequate hydration, electrolyte balance, and reduces metabolic acidosis risk.

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

Heat stress management isn’t just about current herd health — it’s about securing the future of your dairy operation. By adapting management practices to mitigate heat stress in calves, you support their growth and development, laying the foundation for a healthy and productive future herd.