Heat stress in calves

High temperature can be strenuous to calves, even more than cold temperature. Above 23°C calves can experience heat stress. The humidity level also plays a role: the higher the humidity, the sooner the calf suffers from heat stress.

Heat stress has the following effects on the calf:

  • Increased body temperature
  • Decreased feed intake
  • Faster breathing and panting
  • Increased water loss
  • Increased water consumption
  • Suppression of the immune system

All these effects will result in decreased growth. As your calves are the future of your herd, you want to give them the best start they can have. Preventing your calves from experiencing heat stress is therefore very important.

What can you do to reduce heat stress in calves?

Increase the air flow over the calves. This will help them release heat. When calves are housed in hutches, open up all the vents. Keep enough space between the hutches in order to give the air the possibility to circulate through the hutches. Create shade above the hutches, by e.g. stretching a clot over the hutches. The most effective way of cooling the calves down is providing misting by e.g. nozzles and fans. However, this may not be feasible for every farmer.

Make sure that calves have unlimited access to fresh drinking water. Calves will need more water to keep hydrated. In case of dehydration feed them an electrolyte treatment with e.g. Nutrifizz.

We know that the calves’ appetite becomes less when suffering from heat stress. However, to stimulate feed intake as much as possible, give more and smaller portions of milk replacer, concentrates and roughage.

Even though it is warm, make sure that the drinking temperature of the milk replacer is 40°C with a concentration of at least 150g/L. This is important for proper working of the esophageal reflex, ensuring the milk ending up in the abomasum.

Clean the pens and hutches more often. This will prevent heat concentrates at the bottom of the bedding and the development of maggots.

Check the calves frequently during the day.

Shave the back of older calves (>3 months). This will help them in releasing heat.

The last tip is to reduces stress factors as much as possible when the temperature is at its highest. Dehorning, for example should be carried out early in de morning or in the evening when temperatures are still lower.