Cattle health3 min read
Summer heat stress in dairy cows: signs, and 9 ways to keep milk flowing
Hot, humid days cut milk, appetite and pregnancy rates, especially in crossbred cows. How to read the warning signs and cool your cows cheaply.
Bangladesh summers are not only hot but also humid, and humidity makes heat much harder on cows: they cool down mainly by breathing and sweating, which works poorly in damp air. High-yielding crossbred cows (Holstein Friesian and Sahiwal crosses) feel it first, because making a lot of milk also makes a lot of body heat.
What heat stress does
- Less feed eaten, so less milk, often within a day or two
- Lower milk fat
- Weaker or silent heats and fewer cows getting pregnant
- More mastitis and lameness
- In severe cases, collapse and death
Warning signs
| Sign | What to look for |
|---|---|
| Fast breathing | More than about 60 breaths a minute at rest (count flank movements for 15 seconds × 4) |
| Open-mouth panting | Mouth open, tongue out, drooling: this is an emergency |
| Behaviour | Standing instead of lying, crowding in shade or near water |
| Feed | Leaving feed in the trough, eating mostly at night |
| Milk | A sudden drop on hot days |
9 ways to keep cows cool
- Shade, always. A shed roof or trees over the cows and over the feeding and water area. A white or reflective roof stays cooler than bare tin; a layer of straw or insulation under tin helps too.
- Air movement. Open the sides of the shed. Fans over the resting and feeding area make a big difference, especially on still, humid days.
- Wet the cow, then dry her. Short spells of water on the back and neck, followed by fans, cool better than a long soak. Don't simply raise humidity in a closed shed.
- Plenty of cool, clean water. A milking cow may drink 3–4 litres of water for every litre of milk, more in summer. Put extra water troughs close to the shed and clean them daily.
- Feed in the cool hours. Give most of the feed early in the morning and in the evening. Fresh feed at night encourages eating when it is coolest.
- Feed quality over bulk. Hot cows eat less, so every mouthful must count: good green grass, a balanced concentrate, and minerals. Ask your vet or nutritionist about extra salt and potassium (electrolytes) in very hot weather.
- Avoid work in the heat. Do not move, treat, vaccinate or transport cows in the middle of the day.
- Fewer cows per shed. Crowding traps heat. Give each cow enough space to lie down.
- Plan breeding. Pregnancy rates fall in the hottest months. Watch more carefully for weak heats and discuss the timing of inseminations with your AI technician.
First aid for a cow in trouble
If a cow is panting with an open mouth, staggering or lying down and cannot get up:
- Move her into shade with moving air
- Pour cool (not ice-cold) water over her body, especially the neck and back, and keep fanning
- Offer water to drink
- Call the vet immediately
See the effect in your records
Record daily milk in FarmFlows and look at the milk chart for May–August. If yields drop on the hottest days, that is your proof that cooling pays. Record fan and shade costs under Finance and compare them with the milk you saved.
Quick checklist
- Shade over cows, feed and water
- Fans and open sides; wet-then-dry cooling
- 3–4 litres of water per litre of milk, troughs nearby
- Feed in the morning and evening
- No handling or transport in midday heat
- Open-mouth panting = emergency