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Tips for preventing heat stress in dairy cattle

By Rodney Woods

Dairy farmers are being encouraged to assess their heat-stress management for cows in the lead up to summer.

The occurrence of heat stress in dairy cows impacts not only animal productivity but also animal welfare.

Agriculture Victoria dairy specialist Sarah Chaplin said dairy farmers should develop a heat-stress management plan.

“The purpose of a plan is to reduce the impact of the thermal environment and slow heat gain,” Dr Chaplin said.

“This allows cows to maintain dry matter intake and consequently milk production.”

Dr Chaplin said a simple and easy way to remember management techniques to assist farmers is SAW: Shade, Air, and Water.

“The provision of shade can be a simple and cost-effective method to reduce the impact of solar radiation on an animal,” she said.

“Shade creates a more tolerable micro-climate, which will potentially reduce thermal load.

“Air movement is an important factor in the relief of heat stress in animals and can be improved by using fans in dairy sheds and yards.

“The last simple management step is to ensure that during summer, animals have increased access to cool drinking water, particularly at the exit to the dairy.

“During hot weather, cows can drink 200 to 250 litres per day of drinking water.

“This could equate to around 87 500 litres a day for an average herd of 350 cows.

“The use of dairy yard sprinklers to encourage heat loss through evaporative cooling can also be an effective method of cooling cows quickly.

“By applying SAW, you can make simple management changes to minimise the impact of heat stress on your animals and improve cow well-being during summer.”

● Further information can be found at Dairy Australia’s coolcows.com.au, while dairy farmers can also sign up for the Dairy Forecast Service alerting them to upcoming extreme heat events at dairy.katestone.com.au
 

Helpful ideas for shade:

● Trees can reduce the radiant heat load by 50 per cent or more.

● If you are considering planting trees, use north-south orientation. Try to plant on the western side of the dairy yard.

● Place shade over the dairy yard. The combination of shade, air movement and sprinklers enables faster milk let down and more incentive for the herd to walk to the dairy.

Tips for air movement:

● Remember air movement under a shade structure is affected by its height and width, the slope of the roof, and the ease with which air can move through the structure.

● Place fans above sprinklers and tilt them down 20 to 30 degrees so they blow air between and underneath cows to enhance whole body cooling.

Tips for water (yard sprinklers):

● Aim for a moderate to large water droplet.

● Use an on/off cycle to sprinkle cows for one to three minutes every 15 minutes. ● Pre-wet the dairy yard before cows arrive.

● For information about further Agriculture Victoria support to dairy farmers preparing for dry seasonal conditions go to agriculture.vic.gov.au/dryseasons or phone the Customer Service Centre on 136 186.