Optimizing environmental conditions for diary cattle in heat stress

When temperatures climb higher than 21 degrees Celsius, especially when combined with high humidity, cows struggle to regulate their body temperature effectively. By giving your dairy herd shade to shield them from the sun, setting up good ventilation systems, and using cooling methods like evaporative cooling or sprinkling, you can help your cattle beat the heat and stay comfortable. Plus, by implementing these measures, you can ensure consistent milk production during the warmer months. 

The importance of offering sufficient shade 

Providing adequate shade to dairy cattle is more than just a welfare concern—it's essential for their productivity and health. It has been shown that providing shade increases rumination and milk yield and decreases rectal temperature. Make sure to offer plenty shaded areas for the entire herd, as only the dominant animals will benefit otherwise. Offering proper shade can also mitigate the negative effects of heat stress on reproduction, ensuring better fertility rates and fewer instances of early embryonic loss. 

Calf igloos provide shade and protection. However, direct sunlight turns the calf igloos into ovens. To avoid this, place the calf igloos in the shade and take into account the course of the sun. Placing the igloos on the north side of a building or under a sun canopy is ideal. If this option is not available, you can set up mobile awnings or sunshades.

Ventilation and air circulation 

Heat emitted from cows can significantly increase barn temperature and humidity, exacerbating heat stress. Implementing effective ventilation systems is crucial to maintaining a comfortable environment for the herd. A good ventilation system prevents the barn temperature from exceeding the outside temperature by more than 2.5-5 °C, ensuring a comfortable environment. 

High-speed overhead fans help to remove humid air from the environment, and from around the animals' body surface. This makes sweating and panting more efficient. Proper ventilation improves convectional heat loss by removing the boundary layer of hot air around the animals, promoting cooling. 

For calf igloos, ensure that there is enough space between the individual igloos so that air circulation is not restricted. A distance of one meter is recommended between the igloos and three meters between the rows but do make sure that the calves still have visual contact with their fellow calves. To allow the calves' body heat to escape better from the igloos, open all the openings in the calf pens. You can also jack up the rear of the calf igloos slightly using a brick or squared timber. This measure greatly improves air circulation and cooling without creating strong draughts.   

Evaporative cooling 

Evaporative cooling is another effective method to reduce barn temperature and alleviate heat stress in dairy cows. Evaporative cooling relies on the principle that water absorbs heat when it evaporates. By introducing water into the environment, either through cooling pads or atomizing nozzles, heat from the surrounding air is absorbed, effectively lowering the temperature. Evaporative cooling can also be used to cool calf igloos, by placing a water nebulizer or a lawn sprinkler behind the igloos.  

While evaporative cooling effectively lowers the air temperature, it also increases humidity levels. If the humid air is not removed from the environment through proper ventilation and airflow, the system may not be able to relieve the heat stress from the cows and may in fact become counterproductive. That's why it's essential to pair evaporative cooling with controlled ventilation to ensure that evaporative cooling is effective. 

Cooling through sprinkling or soaking 

Sprinkling or soaking cows with cold water is a simple yet effective method to reduce heat stress. With this method, cows are sprinkled with large water droplets at the feed bunk for approximately 30 seconds at a time. The water evaporates upon contact with the skin, reducing body heat and effectively cooling the cow. It's crucial to ensure that the cows don't get too wet, and that the excess water is drained from the area. 

Sprinkling does however require significant amounts of water, which may not be sustainable in regions with water scarcity. Therefore, it is recommended to implement the previous measures first before adding water sprinkling as a cooling method.  

Research has shown that cows may exhibit avoidance behavior when sprinkled excessively. When choosing water sprinkling as a cooling method, it is essential to monitor the reactions of the animals and adjust the method accordingly. 

Ensure quality bedding and flooring 

Cows should ideally spend a lot of time lying down because it aids in rumination and overall health. However, during periods of heat stress, cows may be less inclined to lie down as it reduces the surface area through which they can release body heat. Since cows can't sweat effectively, they rely on this surface area to dissipate heat. To help dairy cows cope with heat stress and to promote rumination, it's essential to provide high-quality bedding and flooring in the barn. Good flooring reduces the risk of sole lesions, which minimizes lameness. Comfortable bedding, such as sand or straw pellets, encourages cows to lie down more often. Besides, keeping bedding clean and dry helps to reduce the risk of mastitis.  

For calf igloos, scatter less straw as it retains body heat and causes the temperature in the igloo to rise. Wet and urine-contaminated beds are dangerous for calves on hot days, so change the bedding frequently. For larger calves, consider setting up sand beds to keep them cool. 

Avoid additional stressors 

Veterinary procedures like vaccinations and examinations, along with changes in stable conditions and transportation, can induce stress in dairy cows. This will increase the strain on their already compromised circulatory systems. It's advisable, whenever feasible, to avoid these interventions and postpone them to cooler days when the cows are better equipped to handle any additional stressors. 

Stay ahead of heat stress

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