Help cows chill out this summer

MEDIA RELEASE
Thursday, 14 January 2010

For immediate release

Help cows chill out this summer

A cool cow in the summer is a happy cow, says DairyNZ animal welfare specialist Dr Adele Arnold.

She says although NIWA’s seasonal climate outlook this summer predicts below average or average temperatures across the country, farmers should still be on the alert for hot weather events and take measures to ensure their stock can cool down.

“AgResearch studies indicate that New Zealand cows can suffer heat stress when temperatures go above 26°C and humidity is high, especially when there is little or no wind,” says DairyNZ Animal Welfare Developer Dr Adele Arnold.

“When cows get hot they will stop eating and if they cannot cool down by using shade or other means, milk production is likely to decrease,” Adele says.

Really hot cows will start to pant and breathe through an open mouth with the tongue hanging out. Respiration rates of greater than 60 breaths per minute are a good indicator that cows are heat stressed.

“Any activity such as walking to and from the dairy, to the water trough, or grazing, increases the risk of heat stress. Digesting food and producing milk also generates heat in dairy cows, and on hot days this can overload their system. High producing animals tend to eat more, and are therefore more susceptible to heat stress,” se says.

If night time temperatures are also very warm, it can become even more difficult for cows to cool down without extra help through good summer management.

When hot conditions are forecast, there are some good short-term management solutions to reduce the risk of heat stress for cows and minimise milk production losses:

1. Graze cows on pasture close to the dairy so they don’t have to walk as far for milking, and let them move at their own pace.
2. Milk cows later in the afternoon/early evening when the temperature has dropped.
3. Use paddocks with shade and provide supplementary feed at night so that the extra heat generated by digestion occurs in the coolest part of the day.
4. Make sure cows always have a good supply of clean drinking water – milking cows can drink over 100L of water per day in summer.

Another good strategy is to cool cows while they wait to be milked by providing shade or using a sprinkler system in the dairy yard. Wetting the skin is one of the most effective ways to cool a cow, however high humidity can make sprinklers less effective on a hot concrete surface. The best way to deal with this is to turn on the water half an hour before milking to cool the yard, use sprinklers that give a large droplet size, and, if possible, use fans to create air movement when there is little or no wind.

Adele says studies show proactive prevention of heat stress is more cost-effective than trying to manage the consequences once cows become heat stressed.

“Although installing sprinklers or shade structures can be costly, they will help to reduce the impact of high heat levels on cow comfort and milk production, especially in hotter parts of the country.”

For more information visit www.dairynz.co.nz
(DairyNZ farmfact 3-15 Managing heat stress in dairy cows)

ENDS

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