During hot summer days, how often do you check if your calves are getting too warm?
Heat stress increases dehydration in calves, reduces their feed intake, and weakens their immune system.
Consequently, there is a high chance that the nutrients they absorb—especially energy—will be used to dissipate heat rather than supporting growth and development. In the short term, this can negatively impact daily weight gain and disease resistance. In the long term, it can impair body development and delay the age at first calving.
VISIBLE SIGNS OF HEAT STRESS IN CALVES:
• Reduced movement and activity
• Faster breathing rate
• Panting with an open mouth
• Decreased feed intake
• Increased water consumption
Despite having a large body surface area relative to their weight, calves still suffer significantly from heat stress. This is particularly severe when there is insufficient cooling at night—for instance, when the ambient temperature at animal level does not drop below 23°C overnight. This commonly happens during summer due to poor ventilation in calf igloos and shelters.
MY PRACTICAL TIPS:
1. PROVIDE SHADE
Place hutches and shelters under shady trees or a roof. If this is not possible, use a sunshade.
Position it about one metre above the hutches and shelters to lower the temperature in the calf's immediate environment by 3 to 4°C.
2. MISTING WATER FOR COOLING
I am generally NOT in favour of misting systems. If you do choose to use them, ensure that the inside of the hutches and shelters remains completely dry (preferably the outside too), and that the calves have enough room to move freely between the inside and outside. Spraying the area near the pens, hutches and shelters works best.
3. FACE HUTCH OPENINGS TO THE EAST DURING HOT SPELLS
Air velocity is typically highest from the east, while direct sunlight inside the pens, hutches and shelters is lowest during the day.
4. ENSURE SUFFICIENT SPACE BETWEEN HUTCHES AND SHELTERS
To guarantee proper air circulation, keep a distance of at least 1.50 metres between individual units. If hutches are placed in multiple rows facing each other, the distance between the rows should be at least 3.50 metres.
5. ELEVATE THE BACK OF CALF IGLOOS AND HUTCHES
If your calf igloos and hutches do not have a solid floor, you can prop the back up on bricks or concrete blocks. This increases air circulation at floor level.
Some farmers use car tyres, but these block the opening much more than bricks or blocks.
In my experience, calves housed in igloos and hutches on straw for long periods tend to push the bedding backward, which can block the bottom opening (especially when using tyres).
This too is Low Stress Stockmanship, so take your responsibility.
Source text Ronald Rongen, Photo Marga Fogt