Why Are Dairy Cows Producing Less Milk? 7 Heat-Stress Measures Farmers Can Use

Hot weather does more than make dairy animals uncomfortable. Heat and humidity can reduce feed intake, increase water consumption and affect milk production and reproduction. NDDB says crossbred and exotic cattle are more sensitive to heat stress, while buffaloes can also struggle to lose body heat.

A 2026 analysis of 16 years of data from Haryana found that high temperature and humidity were associated with lower milk production, particularly in buffaloes and crossbred cattle. Indigenous breeds such as Sahiwal and Hariana showed greater tolerance to climatic stress in the study.

Farmers can reduce heat load through simple changes in housing, water access, feeding and cooling. The right combination matters because heat stress affects animals through several pathways at the same time.

1. Give animals enough clean water

Water should remain available throughout the day during hot weather. Heat-stressed animals increase their water intake as the body tries to control temperature. NDDB lists increased water consumption among the major physiological responses to heat stress.

Water troughs should be kept clean and placed where animals can reach them easily. Farmers should check water availability more frequently during hot periods, particularly for high-yielding animals.

Water alone does not remove heat stress. Animals also need shade, ventilation and, where conditions require it, additional cooling. A shaded water point can also reduce the need for animals to walk repeatedly under direct sunlight.

2. Improve shade and ventilation

A dairy shed should protect animals from direct sunlight while allowing air to move through the structure. Poor ventilation can trap heat and humidity inside the shed, increasing the thermal load on animals.

Fans can improve air movement, while sprinklers or misting systems can provide evaporative cooling where humidity conditions allow them to work effectively.

ICAR-National Dairy Research Institute reports that mist and fan cooling was effective in reducing heat-stress effects in crossbred cows and helped maintain milk production and feed consumption during hot conditions.

Farmers do not necessarily need an expensive cooling system. Improving roof shade, airflow and access to a cooler resting area can provide a starting point, particularly for small dairy units.

3. Watch for early signs

Farmers can identify heat stress by observing animal behaviour. Panting, faster breathing, increased water intake and reduced feed consumption can indicate that an animal is struggling with heat.

Research on Jersey crossbred cows found that respiration rate was a useful indicator of increasing heat stress. At higher thermal-humidity levels, high-yielding cows experienced significant declines in daily milk production.

A 2026 livestock-data study involving Indian smallholder dairy systems also found panting scores useful for assessing heat stress. The project has collected hundreds of thousands of observations across multiple states and identified temperature and thermal-humidity conditions as major factors.

Farmers should pay particular attention to animals that continue panting after resting, spend less time eating or show marked changes in normal behaviour. Early action can reduce the severity of heat stress.

4. Adjust feeding during hot periods

Heat stress can reduce dry-matter intake. When animals eat less, they receive less energy and nutrients for milk production. ICAR researchers recommend nutritional management alongside housing and cooling measures to maintain production during heat stress.

Farmers should avoid unnecessary handling during the hottest part of the day. Feeding during cooler hours can also encourage animals to eat when heat load is lower.

Ration changes should be made with veterinary or animal-nutrition advice, especially for high-yielding animals. Farmers should not add supplements or substantially alter the ration simply because temperatures rise.

5. Use cooling at the right time

Cooling works best when farmers match the method to local temperature and humidity. ICAR research on Sahiwal cattle found that misting was more effective under hot-dry conditions, while splashing performed better under hot-humid conditions for reducing physiological heat-stress responses.

This shows why one cooling method cannot be recommended for every farm. Water-based cooling can be useful, but excessive wetting in humid conditions can reduce evaporation and provide less benefit.

Farmers should also ensure that wet animals have adequate airflow. Fans combined with appropriate water cooling can help evaporation and reduce body heat.

6. Pay more attention to high-yielding animals

High-producing dairy animals generate more metabolic heat and can be more vulnerable during hot weather. Research on Jersey crossbred cows found that high-yielding animals experienced a significant decline in milk production when thermal-humidity conditions became severe.

Farmers should identify their highest-producing cows and buffaloes and give them priority for shade, water and cooling. Pregnant animals and animals recovering from illness may also require closer observation.

Breed also matters. The 2026 Haryana analysis found greater climate tolerance among indigenous breeds such as Sahiwal and Hariana compared with buffaloes and crossbred cattle.

This does not mean indigenous breeds cannot suffer from heat stress. It shows that animals can differ in their ability to cope with high temperatures and humidity.

7. Prepare for longer heat periods

Climate change makes heat management a year-round planning issue in many dairy regions. Rising temperature and humidity can increase heat load, while extreme heat can arrive during periods when farmers are not prepared.

A climate-resilient dairy shed should provide shade, ventilation and reliable water access before severe heat begins. Farmers can also monitor local weather forecasts and increase cooling measures when hot conditions are expected.

NDDB has developed a heat-stress supplement called Pashu Sheetvardhak. The board says its use at 350 grams per animal per day improved milk yield by up to 11% and fat content by up to 7% in its reported testing. Farmers should seek professional advice before using any supplement.

The wider lesson is that heat management should not focus only on milk yield. Heat stress can also affect fertility, feed intake, animal welfare and health. NDDB lists reduced reproductive efficiency among its effects.

For farmers, the first steps are practical: provide clean water, improve shade and airflow, watch breathing and feeding behaviour, adjust management during the hottest hours and give greater attention to vulnerable animals.

As temperatures and humidity patterns change, these measures can help dairy farmers reduce some of the production losses linked to heat stress. The most suitable approach will depend on the breed, shed design, local climate, herd size and available resources.