Cooling Systems for Dairy Cows Under Heat Stress

Introduction

 

Heat stress can lead to significant economic losses in dairy farming. Previous studies have focused on the costs of milk production losses and investments in cooling systems. Heat stress results in production losses other than milk production, including increased risk of mastitis, reproductive problems, and increased death loss. In addition to these animal performance losses, variable treatment costs, breeding expenses, decreased milk quality, and increased labor are also associated with heat stress.

 

Various options are available to mitigate the effects of heat stress, including providing shade, improving ventilation, and ensuring an adequate water supply. Within the scope of ventilation, cooling systems that utilize showers and fans are preferred. However, proper installation of the system is crucial.

 

This article aims to provide information on the installation of cooling systems that use showers and fans to mitigate heat stress for dairy cows.

 

 

 

Heat Stress in Dairy Cows

 

McDowell defines optimum environmental conditions for dairy cows as a temperature of 13-18°C, relative humidity of 60-70%, wind speed of 5-8 km/h, and moderate solar radiation. Dairy cows in lactation can tolerate varying environmental conditions within certain limits. However, when climatic elements shift towards more extreme conditions, it leads to increasing stress on the cows.

 

Factors such as the breed, age, condition, and productivity level of the animals play a significant role in their susceptibility to adverse conditions. In stress conditions, dairy cows experience reduced performance, affecting the economic viability of dairy operations. Research indicates that heat stress negatively impacts performance in cattle living in tropical and subtropical climates. Harris (1992) reports that the decline in milk production due to heat stress begins when the daily average environmental temperature reaches 24°C. Chase et al. (1988) recommend taking precautions and implementing cooling measures when the environmental temperature exceeds 38°C and the relative humidity is at 20%. Keown and Grant (1997) note that at temperatures above 25-26°C, cattle reduce their feed intake, resulting in decreased milk production. When the air temperature surpasses 32°C, milk yield can decrease by 3-20%.

 

Management Options for Heat Stress

 

To mitigate the effects of heat stress, various management options are available. Providing shade, improving ventilation, and ensuring an adequate water supply are some of the recommended strategies. Among these options, cooling systems that use showers and fans within the ventilation framework are preferred. However, the proper installation of the system is crucial to its effectiveness.

 

Heat Stress Management in Dairy Farms

 

It is essential to assess whether the animals on the farm are experiencing stress. A simple test involves measuring the rectal temperature of ten cows from the herd. If seven or more of these cows have a rectal temperature above 39.4°C, the cows are likely experiencing stress. The rectal temperature values tend to be higher during the afternoon hours when the environmental temperature and heat load on the animals are at their peak. If the rectal temperature of the cows exceeds 40°C, it indicates severe stress. An increase in respiratory rate is another indicator, with a knowledgeable observer needed to accurately assess it. If the cows have a respiratory rate of 80 breaths per minute, there is likely mild stress, while a rate exceeding 100 breaths per minute indicates severe stress, necessitating immediate action.

 

Cooling Systems for Mitigating Heat Stress

 

The most economical cooling system involves the use of misting and fan-drying applications. Misting, which involves creating small droplets of water when done correctly, is effective in cooling the environment but is most beneficial in areas with low relative humidity.

 

Components and Working Hours of Cooling Systems

 

Misting should be designed to wet the cow’s skin without causing excessive runoff. After misting, fans should be used to remove the moisture from around the cows, allowing for evaporative cooling. This process is known as “evaporative cooling.” In areas with low or very low relative humidity, high airspeed is not necessary. However, in regions with high humidity, powerful airflow is required to accelerate evaporation. The fans are responsible for this function. When the ambient temperature exceeds 24°C, it is recommended to have an airspeed of 12-18 km/h at the cow level. Studies have shown that providing 190-280 liters of water per cow per day can reduce mastitis risk.

 

Farm Requirements for Cooling Systems

 

Before implementing a cooling system, it is essential to ensure that the farm meets certain requirements:

 

– Provide a daily supply of 100 liters of water per cow.

– Ensure shade in areas where cows will be cooled.

– Establish a system to collect and drain excess water.

– Have access to electricity.

– Allow for feeding near the cooling area.

 

If these requirements cannot be met, it may be necessary to consider alternative cooling systems. Additionally, each farm should explore solutions tailored to its specific conditions.

 

Principles of Shower and Fan Cooling Systems

 

Shower applications should be adjusted to wet the cow’s skin adequately, creating droplets that do not flow off quickly. Fans should be used to remove the humidity around wet cows after showering. Fans can be continuously used to accelerate airspeed and evaporative cooling. Misting and fan systems should be in place at least two weeks before heat stress occurs to allow cows to become accustomed to the system. The system should be programmed to operate continuously during periods of heat stress.

 

Installation Guidelines

 

When installing a cooling system, the following guidelines should be considered:

• Properly position the fans and misters to ensure even coverage in the cooling area.
• Ensure the misting nozzles are directed toward the cows, avoiding water wastage.
• Maintain a distance of approximately 1.5 to 2 meters between fans.
• Position fans at an angle of 15-20 degrees upward to maximize airflow.
• Install fans at a height of 3.5-4 meters for optimal coverage.
• Use high-pressure misting systems for effective cooling.
• Monitor and maintain the system regularly to ensure its effectiveness.

 

 

Conclusion

 

Mitigating heat stress in dairy cows is essential to maintain their health and productivity. Cooling systems that use showers and fans can be highly effective when properly installed and managed. Dairy farmers must assess the environmental conditions on their farms, provide essential resources, and implement cooling systems to ensure the well-being of their cattle and the economic sustainability of their operations. Proper installation, operation, and maintenance of these systems are crucial for achieving the desired results in reducing heat stress and its associated negative impacts on dairy cow performance.

• December 12, 2023
• Dairy Farm Operations
• burkayalgancomtr

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