KARNAL, INDIA (NYTIMES) – Inside a shed in the northern Indian state of Haryana, the sound of flutes floated softly from loudspeakers. The audience, grazing silently, was dozens of cows, the unwitting subjects of an experiment in music therapy.

The orchestrators of this scene were a group of scientists studying a simple question: How much does withering heat affect milk production? For India’s dairy-loving population, another season of rising temperatures has left an answer at their doorstep, as prices have increased for their morning milk deliveries once again.

The scientists of the National Dairy Research Institute are quietly working to preserve India’s status as a dairy powerhouse in the face of the country’s acute threat from climate change, conducting studies on everything from developing new breeds of buffalo to testing new crops of shrubs for protein content.

As part of this work, a team pored over daily data on yields from hundreds of animals after late-spring temperatures rose as much as 5 deg C above the average of previous years. While the warmer months normally see a drop in yield, the researchers found that heat stress in April had directly resulted in an additional decline of nearly 11 per cent in milk production among healthy crossbred cattle.

“The animal is fighting physiologically to adjust itself, and also give 2 or 3 litres of milk,” said Ashutosh, the team’s leader, who goes by one name.

India, the world’s largest producer of milk, generates more than 200 million tonnes every year. The dairy industry, which relies on 80 million farmers across the country, most with small herds, has grown steadily and now accounts for nearly 5 per cent of India’s economy.

In a sign of the country’s craving for dairy products – from slow-cooked chai to curd and cheese to the butter and cream that go into seemingly every dish – only a small fraction of the massive production goes to exports.

Stress on animals is just one way that extreme heat is challenging this crucial industry. In announcing a 4 per cent rise in milk prices last week – the second increase this year – dairy producers cited a nearly 20 per cent jump in the cost of feed for cattle.

While rising prices for fuel and other necessities have not helped, scientists and farmers point to how extreme weather is exacerbating an already troubling fodder deficit that is holding India’s dairy industry back from further growth.

The wilting heat came earlier this year than usual, with temperatures frequently reaching 45 deg C in April and soaring as high as 49 deg C in May. And it stayed hot for long stretches.

Rainfall, on the other hand, was erratic. The fields were flooded in earlier months when farmers expected less rain, while during the period that precipitation would help mitigate the heat, rainfall was below the norm. In the state of Punjab, farmers reported as much as a 15 per cent drop in the wheat harvest, which affected the availability and quality of cattle fodder.

“Production of wheat came down, so the price of cattle fodder, particularly wheat straw, went up,” said Sudhir Kumar Tyagi, who procures milk from farmers in the state of Uttar Pradesh and supplies it to parts of the area around New Delhi, the capital.

“From March to September, the milk production normally remains low, and it picks up again after that,” he said. “But this year, because of intense and prolonged heat, the decline in summertime production of milk was 10 to 15 per cent more.”