Cooling Cows with Positive-Pressure Ventilation
Traditional holding area designs are dependent on natural ventilation to bring fresh air into the cow pen. This system can be compromised by restrictions in air movement due to adjacent buildings, attached utility rooms or even the lack of air movement on still days. These limitations can cause a buildup of humidity and heat in the holding pen. Traditional large circulating fans can create velocity but does not guarantee proper ventilation.
A high producing cow will exhale 4 gallons of water and produce 5000 BTU daily. Heat per square foot in the holding area will range between 375-525 BTU. As a cow’s body temperature increases, cows will stand for longer periods when they return to the free stalls in order to dissipate their body heat. The decrease in lying time leads to lower dry matter intakes, decreased production and increased lameness. Limited perspiration by cows requires wetting of the skin, along with the movement of air to increase the benefits of evaporative cooling.
Utilizing tubes that stretch across the entire holding area disperses fresh air from outside the building in places where natural ventilation isn’t able to reach the cows. Properly designed systems will combine the right fan, tube diameter, and a multitude of correctly sized holes to direct 400 CFM to the backs of all the cows throughout the holding area. The result is more effective cooling of the cows with less fans and energy consumption than have traditionally been used.
The School of Veterinary Medicine, University of Wisconsin, has developed the Positive-Pressure Tube Calculator© to help design a customized ventilation system. Landmark Services Cooperative does have trained staff that can assist your farm.