Heat Stress Can Cut Milk Production, What Dairy Farmers Should Do

Heat stress can reduce feed intake, milk production and reproductive performance in dairy animals. The National Dairy Development Board says high temperatures and humidity can cause faster breathing, higher body temperature, increased water intake and reduced feed intake. Buffaloes can face greater heat stress because of their dark skin and fewer sweat glands.

The problem becomes more serious when animals remain in poorly ventilated sheds without enough shade or drinking water. NDDB recommends combining housing changes, cooling measures and feeding adjustments to reduce heat load and protect productivity during hot conditions.

How does heat stress affect milk production?

Heat stress changes how animals use energy. Instead of directing nutrients towards milk production, their bodies use more resources to maintain normal temperature. Animals may also eat less, reducing the nutrients available for milk production.

NDDB has reported that heat stress can reduce milk yield by 10–30% during first lactation and 5–20% during second and third lactations. The impact varies with breed, weather, housing, nutrition and the severity of heat exposure.

Farmers may notice animals spending more time standing, panting, drinking water and eating less. These changes can appear before a major decline in milk production, making early observation important.

Buffaloes require particular attention because their dark skin absorbs more solar radiation and they have fewer sweat glands than cattle. NDDB says buffaloes are more prone to heat stress for these reasons.

Clean drinking water should remain available throughout the day. NDDB says a healthy adult dairy animal normally requires about 75–80 litres of water daily, while requirements can increase during summer and with higher milk production.

The amount also depends on feed, temperature, humidity, body size and milk yield. NDDB recommends free access to clean drinking water and says crossbred cows and buffaloes should receive at least 100 litres daily during summer to manage heat.

Water troughs should remain clean and should preferably be placed under shade. NDDB specifically recommends shaded drinking areas because animals can lose some cooling benefit when water becomes hot under direct sunlight.

Farmers should check troughs several times during the day, especially during periods of high temperature. Empty or dirty troughs can restrict water intake precisely when animals need more water for cooling.

Can better sheds reduce heat stress?

Yes. Shade and air movement are among the basic measures recommended by NDDB. Farmers should avoid keeping animals in enclosed sheds where hot air becomes trapped around the animals.

NDDB recommends a thatched roof at least nine feet high where trees are unavailable. Agri-nets can also provide shade, while ventilators, fans or blowers can improve air movement inside covered sheds.

The direction and design of the shed also matter. Open sides can improve ventilation when local conditions allow it, while barriers can protect animals from hot winds. Farmers should avoid overcrowding because closely packed animals generate additional heat.

Animals under heat stress often eat less. Farmers can respond by offering more palatable and digestible feed and shifting feeding towards cooler parts of the day.

NDDB recommends feeding animals during morning, evening and night hours during hot conditions. ICAR also advises increasing green fodder, chopping long fodder and providing balanced nutrition during extreme summer conditions.

Farmers should avoid sudden changes in feed. NDDB recommends gradually changing rations and chopping fodder before feeding to improve digestibility and reduce wastage.

Mineral supplementation also matters. ICAR recommends sodium, potassium, minerals and vitamins during heat stress, while NDDB advises using potassium-rich mineral mixtures during hot weather.

Can sprinklers or bathing help?

Cooling the animal’s body can reduce heat load. NDDB recommends misting or sprinkling water over animals and increasing air circulation to support evaporative cooling.

For small dairy farms, regular bathing can be a practical option where enough clean water is available. NDDB recommends bathing crossbred cows and buffaloes twice daily during summer, along with adequate drinking water.

Farmers should also provide shade immediately after cooling. Leaving wet animals under direct sunlight can reduce the benefit of the cooling measure.

High-producing dairy animals can face greater heat pressure because milk production itself creates a substantial demand for water and nutrients. Crossbred and exotic cattle can also be more sensitive to heat than indigenous breeds.

Pregnant animals and animals in early lactation need careful monitoring. Heat stress can also affect reproduction, including conception rates, embryo development and semen quality, according to NDDB.

Farmers should therefore watch reproductive performance as well as milk yield. A drop in conception rates during hot periods may be linked to heat exposure alongside other nutritional or management factors.

Small dairy farmers do not necessarily need expensive cooling equipment. Shade from trees, thatched roofing, adequate ventilation, clean water and feeding during cooler hours can reduce heat exposure.

Farmers can also place drinking-water troughs under shade, use wet gunny cloth where appropriate and allow animals to rest in cooler areas. NDDB recommends these basic measures as part of heat-stress management.

Larger farms can consider fans, sprinklers, wet curtains or other cooling systems. ICAR says commercial farms may use fans, wet curtains, air coolers or air conditioners during extreme summer conditions.

Can supplements help during heat stress?

Nutrition can support animals during heat exposure, but supplements should not replace shade, water and cooling. NDDB has developed a heat-stress supplement called Pashu Sheetvardhak for dairy animals.

NDDB reports that feeding the supplement at 350 grams per animal per day improved milk yield by up to 11% and fat content by up to 7% in cows and buffaloes during heat-stress periods. Farmers should follow product-specific guidance before use.

Farmers should check whether animals are drinking normally, eating enough, panting more than usual and spending excessive time standing. They should also inspect water troughs, shade, ventilation and the condition of the shed.

A sudden fall in milk production should not automatically be blamed on heat. Disease, feed quality, water problems and other management issues can also reduce production. Veterinary advice is needed when animals show severe or persistent symptoms.

Heat management is part of routine dairy management, not a single action taken during the hottest days. Providing water, shade, ventilation, suitable feed and cooling can help animals cope with high temperatures.

For farmers, the most practical starting points are simple. Keep clean water available, improve shade and airflow, feed during cooler hours and monitor animals closely. These measures can help reduce heat stress and protect milk production and reproductive performance.