Take steps to keep cows cool

With El Niño conditions predicted, herds in drought-affected regions will be particularly affected by heat and humidity, while dairy regions in southern Australia should also plan for any extreme heat.

University of Queensland’s School of Agriculture and Food Sciences Associate Professor John Gaughan, who has been researching heat stress in dairy cows for 20 years, says early intervention is the key to reducing heat stress.

“I think we can safely say the incidence of heat stress is increasing – especially extreme events,” Assoc Prof Gaughan said.

“But having said that, the adverse outcomes have decreased, in part because people are more aware, and have some strategies in place to decrease the negative effects.”

Ensuring cows are cooled before and after milking and being proactive are key strategies used on farm.

“Don’t wait until cows are hot – be proactive,” Assoc Prof Gaughan said.

“Research is showing that night time minimum temperature is in some ways more important than the day time maximum – if it is a hot night, earlier and longer cooling may be necessary.”

Assoc Prof Gaughan’s research has highlighted the potential for cows in southern regions to be susceptible to extreme heat events.

“Cows in the south are particularly at risk of heat stress coming out of winter, and are more exposed to extreme heat events,” Assoc Prof Gaughan said.

“In northern regions, high heat load, primarily due to high humidity, could subject cows to a higher incidence of heat stress.

“High production cows are also more at risk of heat stress – in terms of milk yields, milk quality and reproduction. The reproduction effects can be long term.”

Western Victorian veterinarian and dairy consultant Tom Walsh says cows will feel the effects of hotter weather more when humidity is higher.

“Having a plan for dealing with hot weather is essential to maintaining a happy, productive herd during summer,” Mr Walsh said.

As costs are increasing on farm, simple steps can be taken to reduce heat stress.

“A lot of farm budgets are becoming tighter and for many farmers, going out and spending money on major infrastructure is fairly difficult right now,” Mr Walsh said.

“But there are shorter term and cheaper options available that can at least give farmers some capacity to get on top of things and minimise any effects from the heat.”

Among the tips shared was running a sprinkler in dairy sheds, reviewing milking times, ensuring water is readily available for cows, and keeping track of which paddocks have accessible shade are simple steps farmers can take to keep cows cool.

Cows begin to feel heat stress at temperatures as low as 25 degrees Celsius and may drink 200 litres to 250l of water per day in hot conditions.

Shade can reduce radiant heat load by 50 per cent or more while wet cows cool down three times faster.

Research has also shown cows prefer to stay cool than feed and intake can be improved by taking feed and water close to shaded areas where cows are resting.

Heat stress can be reduced by milking as early as possible in the morning and after 5pm in extreme conditions.