Keeping your cows cool this summer

Trudy and Matthew Holmes.

By Jacqueline McGowan – DairyNZ developer in the animal care team


21 December 2018

No one likes being too hot, and our cows are no exception. 

Some of you might be surprised to know when temperatures start to feel nice and pleasant for us, it’s actually already too hot for our cows.

Research has found that cows are most comfortable in temperatures between four and 20 degrees Celsius. So, their comfort zone is actually around 10 to 15 degrees lower than us. This means when temperatures start to get in the mid-20s, let alone near the 30s, our cows are increasingly at risk of experiencing heat stress.

Cows affected by heat stress may be irritable and lethargic, as well as produce less milk as they consume less feed, so it’s important to keep them cool when the mercury starts to rise.

With that in mind, now is a good time if you haven’t already to come up with a plan to keep your cows cool this summer.

We often focus on ensuring we have a plan from a feed perspective, but it’s equally as important to keep in mind the impact heat can have on our cows wellbeing.

While we can easily grab an ice-cream, icy cold bevy, slap on a hat and avoid the sun, it can be a bit more challenging for us to keep our cows cool.

Tactics to minimise heat stress

Those of you without trees on your farm maybe thinking, ‘what can I do?’

Trees are obviously a great long-term option, and I know some of you have begun planting for shade and shelter, or thinking about it, which is great. But the reality is they can take a long time to grow.

In the meantime, if you don’t have any, or limited, trees on your farm there are a few simple, practical things you can do to help alleviate the effects of heat on your cows that don’t require a huge investment, or time.

Consider changing your milking time to earlier in the morning or later in the afternoon so your cows aren’t having to walk to and from the milking shed during the heat of the day. You may even like to consider going to once-a-day milking.

If possible, try putting your cows in paddocks closer to the milking shed during the day so they have less distance to walk, and allow them to take their time. No one likes exercising in the heat, I know I don’t.

Installing a temporary shade cloth at the milking shed or over off paddock facilities can also provide much needed relief for your cows from the suns rays. Sprinklers over the dairy yard to wet the cows’ coats, and fans, are another option you may like to consider.

Your cows will be consuming more water to keep cool, so extra troughs in paddocks, at the milking shed and along races won’t go amiss.

Also, I know it should go without saying, but remember to check troughs regularly to ensure they’re clean and check flow rates are high enough that there isn’t a risk of them ever running low as lactating cows require more than 100 litres of water a day.

As many of you may know, feed with a high fibre content can increase the heat of fermentation in the rumen, increasing the heat load on the cow. If high fibre supplements feature in your cows’ diet, you might like to consider feeding them at night when it’s cooler.

These are just a few short term options you may like to consider to keep your cows cool this summer. But I’d encourage you to also start exploring your long-term options, especially given climate change forecasts suggest our summers are to become longer, hotter and drier.

Trees are an obvious choice and the ‘Trees for shade’ guide our website is a great starting point for coming up with a plan. The guide is available at

For more information on how to mitigate the risk of heat stress to your cows visit

Farmer tips to prevent heat stress:

North Canterbury dairy farmer James Daly is no stranger to farming in hot and dry conditions.

He has been farming in Cheviot, which typically experiences scorching summers, for the last four seasons.

He says there are “lots of little things” farmers can do to keep their cows cool.

“The main thing is to make sure they have plenty of water available. That’s the most crucial thing. I’ve put in extra troughs for that reason.”

He also recommends checking water pressure to troughs to ensure they fill up quickly.

On scorching days, he also milks later to avoid the heat of the day.

“It doesn’t hurt to milk a bit later, so you’re avoiding milking at 2/3pm during the heat of the day.”

His farm has a bit of natural shelter, but he is looking at doing a bit more planting in the near future to provide his cows with more shade.

“If we know it’s going to be hot, we also put cows in sheltered areas. We try to do that as much as we can, but it often depends on the amount of feed available in those paddocks.”

He says sprinklers in yards are another good option, and they are looking to install these in the near future.

Helen Thoday

Jacqueline McGowan

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