Heat Stress in Dairy Cows and Buffaloes: Protect Milk Yield in Pakistani Summers

Across much of Pakistan, temperatures from May to September push dairy animals far beyond their comfort zone. High-yielding crossbred cows and black-skinned buffaloes suffer most. Heat stress lowers feed intake, milk yield and fertility, and the effects on fertility can last for weeks after the heat passes.

How hot is too hot?

Heat stress depends on both temperature and humidity. Scientists combine them in the temperature-humidity index (THI), and dairy cattle generally begin to feel stress when the THI rises above about 68–72 — which in Pakistan means many summer days, and even warm nights during the humid monsoon. High-yielding animals produce more internal heat from digesting feed, so they feel the heat sooner than dry or low-yielding animals.

A practical rule: if you are uncomfortable standing in the shed at midday, your animals are already losing milk.

Signs of heat stress

• Rapid, open-mouth breathing and panting.
• Drooling and standing instead of lying down.
• Crowding into shade or around water.
• A drop in feed intake and milk, and fewer visible heats.

Shade and air movement

• Provide shade over resting and feeding areas. A high roof (and an insulated or light-coloured one) stays much cooler underneath.
• Keep sheds open on the sides for airflow; use fans where electricity allows.

Water cooling

• Sprinklers or misters combined with fans are one of the most effective tools: wet the skin, then let moving air evaporate it. Cycle the water on and off rather than soaking continuously.
• Buffaloes benefit greatly from wallowing or regular water showers because they have fewer sweat glands.

Drinking water

A lactating animal can drink well over 80–100 litres a day in summer. Provide clean, cool water at all times, close to feeding and resting areas, with enough trough space that timid animals can drink too.

Feeding in hot weather

• Feed in the cooler hours — early morning and evening — and push feed up so it is always available.
• Offer good-quality green fodder and avoid very dry, stemmy roughage at midday.
• Keep minerals and salt available; animals lose electrolytes through panting and sweating.
• Make diet changes gradually to protect the rumen.

Emergency signs

Call a veterinarian urgently if an animal shows very fast, laboured breathing with the tongue out, staggering, collapse, or a very high body temperature. Move her to shade, wet her body with cool (not ice-cold) water and keep air moving while you wait.

Breeding in summer

Conception rates usually fall in the hot months, particularly in buffaloes. Keep heat detection going, cool animals before and after insemination, and record results so you can see the seasonal pattern on your own farm.