Heat stress in dairy cattle

5 minutes reading - published on December 10, 2019

An optimal living environment for dairy cattle requires a good climate. After all, a pleasant barn climate contributes to healthy cattle with high productivity. For dairy cows, the optimum ambient temperature is between -5 and 18 °C.

At a temperature of 22 °C in combination with a high humidity, a cow can already suffer from the heat. We call this phenomenon heat stress. 

Symptoms
The most noticeable sign of heat stress is that cows start drinking more. In addition, they sweat and pant more. Cows sweat at only 10 percent of the human sweat rate. It is therefore difficult for them to get rid of the heat, which makes them sensitive to heat stress. Cows also produce more saliva during warm periods, causing them to lose a lot of moisture. This can lead to ruminal acidosis. Furthermore, in the event of heat stress, cows stand up to two hours less per day. When cows are standing, they can easily lose their heat.

Effects
In times of heat stress, feed intake is reduced by 8 to 12 percent or more. This reduction in feed intake reduces the production of volatile fatty acids in the rumen, resulting in a reduced production. Other side effects that are often seen in heat stressed cows include a reduction in fertility (tank cell count is increasing), an increase in embryonic loss, an increase in hoof problems (less lying down) and more cases of clinical mastitis. 

Solutions
Some heat stress is inevitable, but effects can be minimized. Before it gets hot you can also make a lot of preparations:

  • Increase the amount of water available for your herd.
  • Adjust the ration to maintain feed intake.
  • Provide shade (when grazing)

If it is really hot, it is especially important that you actively cool the cows. Above 26 °C, it is recommended to wet the cows and to cool them with fans. However, it is important that the udders remain dry.

In addition to the above, increasing the air flow is an important measure to prevent heat stress. Ensure that air can move freely through all parts of the barn. Natural ventilation can be supported by fans.

The refreshed air that is spread through the fans reduces the feeling of temperature and prevents the cows from quickly becoming bothered by the heat. A minimum air velocity of 2 m/s is essential to achieve this effect. Axial fans are still the most used. They can provide a targeted air flow at a relatively high speed. They are therefore often placed behind the feeding fence or above the stalls. This invites them to eat or lie down. Both are important for optimum milk production.

If you have any questions about ventilation in dairy barns or if you want to know more about the solutions we have to offer, please contact us and we will be happy to help you!

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published on December 10, 2019

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