Farmers protect dairy cows from extreme heat

At 4 a.m., while many residents of Yen Bai Commune in Hanoi are still asleep, the lights at Phan Thi Hau's dairy farm have long been on. Along both sides of the barn, industrial fans run continuously to help keep the herd cool.

While her husband checks the rooftop water-spraying system, Hau busies herself cleaning the barn and preparing feed. The family has been engaged in dairy farming for many years, but in recent summers their daily routine has had to change significantly.

"If we start any later, it gets unbearably hot, and both people and cows become exhausted. We have to wake up much earlier now to finish the most important tasks before the temperature rises," she said.

Ba Vi has long been recognized as one of Hanoi's leading dairy farming regions. Favorable natural conditions and a long-established tradition of livestock production have enabled the area to develop concentrated dairy farming zones, providing livelihoods for thousands of households. However, the increasing frequency of extreme weather events is posing new challenges for the industry.

The workday begins before dawn

For dairy farmers, virtually every task follows a strict and unchanging schedule. Cows must be milked every 12 hours, twice a day, without delay. Any deviation from the schedule can immediately affect milk production, increase the risk of mastitis, disrupt the lactation cycle, and have lasting consequences for the animals' health.

Under cooler conditions, the early morning milking routine proceeds relatively smoothly. This year's prolonged heat, however, has forced farmers to start even earlier to complete milking before the day's intense heat reaches the barns.

At Hau's farm, most physically demanding work is carried out in the early morning or late afternoon. The period from late morning to early afternoon is largely devoted to monitoring the herd's health, checking the cooling system, and minimizing activities that could expose the animals to additional heat stress.

Dairy cows are highly sensitive to environmental changes. Prolonged periods of hot weather cause the animals to eat less, drink more water, and move more slowly, ultimately reducing milk production.

During peak heatwaves, cooling fans must operate continuously. Water is repeatedly pumped onto the metal roofs to reduce heat buildup, while the barn floors are cleaned and cooled regularly. Although these measures help mitigate the effects of extreme temperatures, they also entail high additional costs for farmers.

To protect their herds from heat stress, dairy farmers in Ba Vi have adopted every available cooling measure. Most farms have installed four to five high-capacity industrial fans that run continuously. In open-sided barns, tarpaulins are used to block direct sunlight, while water distribution systems continuously spray the metal roofs to lower temperatures.

As a result, electricity bills have doubled compared with normal levels, not including the extra costs of nutritional supplements, cooling vitamins, and electrolyte solutions added to the cows' drinking water.

To offset the rising costs of maintaining their herds during the hottest months of the year, many farming families have had to tighten their household budgets and cut back on daily living expenses.

At a handful of better-funded farms, misting systems have been installed along the barns to provide additional cooling. However, field observations indicate that only a limited number of dairy households have been able to invest in such modern equipment. Most barns in Ba Vi remain traditional open-sided structures designed for natural ventilation, leaving farmers with few effective options when outdoor temperatures climb to extreme levels.

A double burden

According to Nguyen Tien Thinh, a livestock specialist at the Ba Vi Dairy and Forage Research Center, high temperatures and humidity have a significant impact on the health of dairy cattle. When environmental conditions exceed the animals' comfort threshold, they are prone to heat stress, which alters their feeding behavior, growth, and milk production capacity. In recent years, heatwaves have become both more frequent and more intense, placing an ever-growing burden on dairy farmers.

"During the hot summer months, a single dairy cow may need to drink more than 50 liters of water per day. Farmers should therefore ensure an adequate supply of clean water and consider supplementing it with electrolytes," Thinh advised.

He also noted that during periods of extreme heat, dairy cows often refuse dry forage, fresh grass, and concentrate feed, instead drinking large amounts of water to cool themselves. Excessive water intake, combined with insufficient fiber and nutrients in the digestive system, can alter the composition of the milk, resulting in a more diluted product.

Ba Vi milk is well known for its rich and creamy taste, with daily butterfat content typically exceeding 3.5%. During periods of extreme heat, however, this figure can decline significantly.

As a result, dairy farmers face a "double burden." On the one hand, production costs rise sharply while milk output falls because heat-stressed cows eat less. On the other hand, milk quality also deteriorates, and more diluted milk often fails to meet the technical standards required for Grade 1 classification.