Expert Interview: Nicolaas Vreeburg on Heat Stress in Dairy Cows

In this Expert Talk video, meet our Dutch cowboy Dr Nicolaas Vreeburg who is answering our questions about heat stress signs and mitigation strategies for dairy operations.

What is temperature and humidity index (THI)?

It’s not only about temperature because humidity is as important as the temperature itself. When humidity is high, cows suffer a lot more from heat stress and that’s why we call the combination the temperature humidity index or THI.

How much the cows can loose during heat stress?

Well the first thing framers see is of course the loss of milk production, which can be 4, 5, 6 liters of milk, but the worst I’ve seen was that cows lose 10 liters of milk during a heat stress period.

In addition, what are the other major signs?

The first thing you can see with the cows is that the respiration rate goes up. Normal respiration rate is only 10, 20 maybe 30 breaths per minute, but if the cows are panting it goes up to 60 or even higher. Which is what we call panting.

The second thing is that cows eat less but bigger meals.

The third thing you can see is that they stand more so they lay less and they stand more in the barn.

What are the longer-term consequences?

When cows change their eating behavior there is a higher risk for ruminal acidosis, the second thing is that because cows stand longer there is more hoof problems, and the third thing is that when heat stress occurs there is more fertility problems.

All farmers know that, but what people don’t know is that the offspring of cows who suffered from heat stress also have production loss during their lifetime.

What are practical tips to succeed?

One: make a really good customized plan to avoid the negative consequences of heat stress.  

Number two is design a well ventilated barn, a good functioning cooling system, smart management and make your ration safe by using for example live yeast.

And number three, using live yeast like LEVUCELL SC and MAGNIVA forage inoculants are the keys to success in the summertime, where the living is easy for us but not for the cows!