Cooling strategies for calf housing

Calves are highly susceptible to the effects of heat stress when temperatures reach 26⁰C. Heat stress causes the calf to use energy to dissipate excess heat from its body, resulting in lower weight gain, compromised health, and difficulty achieving growth targets for age at first calving or age to market.

Heat stress can affect calves housed both in hutches and inside barns. It is essential to monitor their behaviour and adjust ventilation accordingly.

Identifying heat stress

Heat-stressed calves can be difficult to identify, because there may not always be a sudden change in behaviour. Monitor calves twice daily (at minimum), and look for an increase in water consumption, reduced feed intake or growth, lethargy, standing when they’re normally lying, higher respiratory rates, panting and/or sweating, and increased sickness.

Hutches

In the summer months, temperatures inside hutches are often higher than outdoors, and calves don’t always have the ability to move to a cooler spot. Consider locating the hutches in a shady area and position them to take advantage of natural airflow.

Depending on hutch style, this could involve opening the rear doors, lowering/opening vents or even propping up the back of the hutch six to eight inches off the ground to facilitate air movement (while avoiding drafts). Consult the manufacturer for their recommendations.

Barns

Inside barns, low ceilings also mimic temperatures experienced in hutches and high amounts of heat can be radiated onto the calf. Opening windows and curtains and adding fans or adjusting ventilation systems for summer air exchange rates will all help remove heat and circulate air uniformly.

According to Harold House, engineer with DairyLogix, calves from birth to weaning require 170 m3/h (100 cfm) of fresh air per calf in the summer to remove heat. However, the actual air exchange required is usually greater than the minimum ventilation requirements, and in summer can be 40 or more room air changes per hour.

If mechanical ventilation is used, being prepared for power outages during summer thunderstorms is also something to be mindful of.

A caveat about misting

Along with optimizing air flow, there are a few other ways to help keep the calves’ environment cool, such as misting with sprayers. This can create the same effect as panting and sweating; heat dissipates with water as it evaporates off the animal. However, in high humidity, the ability to cool by evaporation is limited due to the moisture already present in the air.

Bedding

Bedding should also be removed more frequently; if wet and dirty, it will retain heat. Sand is better than straw or shavings at dissipating heat, but all bedding must be clean, dry and comfortable.

Conclusion

Late spring and summer can bring highly variable and unpredictable weather. So far, this year has been no exception, and it is important to consider the effects of heat stress on all groups of cattle in your barn. Regularly assessing calf behaviour, adjusting ventilation, and providing other cooling measures such as shade, fresh bedding, and of course plenty of fresh, clean water will help keep your calves cool and thriving throughout the summer season.