Monitoring is key to avoid dairy cows overheating

New Zealand Veterinary Association

Media Release 

4 February 2009

Monitoring is key to avoid dairy cows overheating

As the weather heats up around the country, veterinarians are reminding dairy farmers to provide adequate shelter and water for their herds.

New Zealand Veterinary Association (NZVA) dairy spokesperson Dr Peter Davidson says while New Zealand farmers don’t usually have to face extreme hot temperatures, our increased levels of solar radiation means dairy cows can quickly overheat.

In addition, there are higher levels of endophytes in summer pasture which can lead to overheating as well. 

“One of the thing farmers can do is monitor the behaviour of their stock. The first sign of heat distress is clustering around the water trough or clustering in groups, trying to get shade from each other.”

Additional signs are drops in production, drooling, panting, decreased cudding, irritability, and in some cases subclinical rumen acidosis. Heat stress can lead to drops in rumen pH, which means some feeds can be unsuitable unless they are balanced with a fiber source. 

Dr Davidson says increased respiration is an accurate indicator.

“If respiration rates are getting above one breath per second you need to start mitigating heat distress.”

"Planning grazing by utilising shaded paddocks during the day and non-shaded at night helps cows stay cool during the day and also warmer during nights," he says.

Dr Davidson also recommends farmers keep cows close to the dairy shed to shorten the walking distance to afternoon milking.

“Farmers can install sprinklers in the dairy shed as the cows enter to compensate for the additional heat from walking to the dairy, which can push body temperatures up about one degree.”

Cows should be wet to the point where water is running off them otherwise local humidity around the cow increases and they can become more uncomfortable.

"Ensure cows are not jammed into the yard tightly without cooling them. Once cows are cooled at milking they are more likely to graze effectively after milking," Dr Davidson says.

He says cows will do their bit to stay cool by standing in shade throughout the day and then grazing at night.

“I think most farmers appreciate the fact their cows get hot, but it’s important to monitor the condition of cows over the peak-heat months.”

ENDS

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