As temperatures continue to fluctuate during the summer months heat stress remains a concern for livestock.
Amongst farm animals, dairy cattle are particularly vulnerable to high temperatures and humidity. Heat and humidity stress in cows can significantly reduce milk production, reproductive performance, feed intake and can even threaten the health and welfare of the herd.
What is Heat and Humidity Stress in Cows?
Heat and Humidity stress occurs when their body heat load exceeds its capacity to dissipate that heat, especially in hot and humid conditions. Cows are naturally poor at cooling themselves; they have limited sweat glands and rely heavily on respiration and behaviour to regulate body temperature.
The Temperature-Humidity Index (THI) is commonly used to assess the risk of heat stress in cattle. A THI above 72 is considered stressful for dairy cows, and the risk increases rapidly beyond that.
Signs and Symptoms of Heat and Humidity Stress…
It is important to recognise the signs early:
- Increased respiratory rate (panting)
- Excessive breathing and drooling
- Reduced feed intake
- Standing more than lying down (to increase surface area for heat loss)
- Bunching in shaded areas
- Drop in milk yield
- Elevated body temperature
- Increased water consumption
Why it matters…
Heat and Humidity stress in cattle has both animal welfare and economic implications:
- Milk production drops
- Reproductive issues
- Immune suppression
- Feed conversion efficiency decreases
Preventing and Managing Heat and Humidity Stress in Cows.
Here are some practical steps to help reduce the effects on your herd:
- Provide Shade – natural or artificial shade is crucial. Trees, shade cloths, or open-sided sheds can reduce heat load significantly.
- Improve Ventilation – good airflow is essential in sheds. Install fans or open sidewalls to encourage air movement.
- Use Misting or Sprinkler Systems – when combined with fans, water-cooling systems can help reduce body temperatures. Avoid over-wetting, which can lead to slippery floors and hoof issues.
- Adjust Feeding Times – feed during the cooler parts of the day ( late evening) to encourage intake. Avoid feeding during peak heat.
- Ensure Constant Access to CLEAN Water – cows can drink up to 50% more water during hot weather. Make sure water troughs are clean and plentiful.
- Monitor Body Condition and Behaviour – Watch for early signs of stress.
- Adjust Diets – high fibre feeds generate more internal heat. Consider consulting with your DN Ruminant Specialist on how to adapt rations during summer months.
Heat and humidity stress is one of the most underestimated challenges in livestock farming. It not only affects cow comfort and welfare but also cuts deeply into farm profitability. Proactive management strategies—such as providing shade, cooling systems, and dietary adjustments—can make a big difference.
A comfortable cow is a productive cow. As climate conditions become more extreme, investing in heat stress mitigation isn’t just smart farming—it’s essential.
Are you struggling with heat stress in your herd? Would you like some more advice? Contact your local DN Ruminant Specialist who will be happy to help…
