Cows cooled by an evaporative tunnel produced more milk and ate up to 12 per cent more feed than those placed merely in shade or under sprinklers, says a US-based study published in October's Journal of Dairy Science.
The findings could be important for dairy firms around the world as they look to increase profitability and efficiency.
Heat can have a big impact on cows. Hot temperatures across the UK this summer meant milk production in July and August was among the lowest on record, according to the Milk Development Council.
Cows can begin to suffer from heat stress at temperatures as low as 22°C, according to Terry Smith, a co-author of the journal article. Temperatures were up to 37°C across Britain and much of Western Europe in July.
Some scientists have predicted world temperatures will rise by another 2°C up to 2050, heating up countries used to a milder weather.
"The advantage of evaporative tunnel ventilation became more dramatic as temperatures increased," said Smith, of Mississippi State University. He said the technology was less effective in higher humidity, but still better than fans or sprinklers.
Cost may deter several UK dairy firms and producers from installing cooling tunnels. Britain's dairy industry continues to suffer from low earnings, and the country's National Farmers' Union estimated milk producers' combined debt has reached £2bn.
New, large-scale facilities incorporating a cooling tunnel system are around 20-25 per cent more expensive than facilities using sprinklers or fans.
"But, as producers will tell you, the increased cost can be rapidly returned in regions with severe heat stress through sustained milk production and better reproductive efficiency during the period of heat stress and beyond," Smith told DairyReporter.com.
He added that a more limited cooling tunnel system could be added to existing facilities on farms "at a fraction of the cost of a new barn".
Early results from additional studies on cooling tunnel technology show it may be beneficial for cow nutrition, fertility and air quality. The results are still being analysed.