Heat stress should be a greater concern than winter cold for dairymen in Kentucky. Heat stress can cause drops in milk production and breeding efficiency, which result in lower profits for the dairyman. The use of an open sidewall free stall barn can help relieve heat stress by allowing improved ventilation of the barn in summer. The benefits of full-wall ventilation include both improved air movement and some potential increase in evaporative cooling. The increased airflow through the barn increases convective cooling of the cows and carries off a greater amount of excess heat and moisture than conventional barns with sidewalls. Additionally, some evaporative cooling of the barn occurs as a greater volume of outside air is moved through the barn. The drier outside air absorbs more of the moisture from urine, feces, and spilled drinking water than the air in a closed barn does. As the moisture is vaporized into the air, heat is removed from the barn and some cooling occurs.
Turner, Larry M. and Chastain, John P., "Full-Wall Ventilation for Dairy Free Stall Barns" (1991). Agricultural Engineering Extension Updates. 26.