Heat stress in cows

Heat stress in cows occurs when they cannot regulate their body temperature due to high temperatures and humidity. The main causes include high temperatures, humidity, poor ventilation, overcrowding, lack of water, and excessive activity. The consequences include reduced milk production and lower reproductive performance. The cow may lose weight or develop health problems. Some measures to relieve it include providing shade, better ventilation, increased access to water, and adjusting their diet.

Homeothermic Animals and Thermal Zones

Dairy cows are homeothermic animals, meaning they must maintain a stable body temperature. They have specific thermal zones for optimal production. When the ambient temperature exceeds these zones, they require more energy to regulate their body temperature.

Measures to Prevent Thermal Stress

Heat stress requires a combination of strategies. We focus on four key areas: ventilation, shading, water, and nutrition.

Ventilation – Spraying

Good air exchange is the first step in ventilating a barn. Once adequate air exchange is ensured, increasing airflow speed can further enhance cooling. MasterFan I fans are essential for maximizing ventilation and airflow. It’s important to note that combining water with fans is more effective than using fans alone. Water without the assistance of fans can lead to increased humidity in the barn.

The spraying system increases evaporation and enhances cooling, thereby lowering the ground temperature. Sprinklers should thoroughly wet the animals, not just the air, to achieve the desired cooling. Additionally, sprinklers should be used before the cattle experience intense stress. Thermal shock from cold water can be fatal to animals already under significant stress.

Water

Water is the main nutrient for cows. Ensure they always have access to fresh and clean water. When suffering from thermal stress, water consumption may increase by 30%-200%. Cold water helps cool them down and improves their feed intake. A cow can consume more than 120 liters of water per day. Check the water flow in the tanks and keep them clean.

Shade

The easiest and most obvious way to help your animals alleviate heat stress is by providing sufficient shade. Sunlight adds a tremendous thermal load to the cow, but thermal energy reflected from concrete floors, walls, and other exposed surfaces also contributes to the thermal load.

Nutrition

Another important step in alleviating heat stress is proper management of the cows’ diet. When the ambient temperature rises, a cow’s appetite decreases. As a result, dry matter intake falls by 10-20%, either short-term or long-term, depending on how long and intense the heat stress is. To maintain their normal body temperature, cows need more energy, which increases their energy requirements by 20-30%.

Offer high-quality feed that is easy to digest and has the correct cutting length. The quality and quantity of the fibers and starches in the feed are crucial for combating thermal stress. Additionally, offer feed with slow starch fermentation so the cow has a steady supply of energy, in the form of glucose, throughout its body. Corn (maize) is the best source of slow-fermenting starch.

Conclusion

Proper ventilation in a barn is not just a matter of comfort, but it directly impacts the overall performance of the farm. Managing the temperature of the animals with proper ventilation improves their welfare, reduces stress, and prevents respiratory problems, which can lead to better milk production and healthier animals.