GUIDELINE 44 Guidelines for Mechanical Ventilation of Dairy Tie-Stall Barns Every enclosed dairy building needs a ventilation system to remove moisture, odors and foul air and to regulate inside temperature. The health and production of the dairy herd and the quality of milk produced are affected by the method and effectiveness of the ventilation system. The over-all efficiency of the system also affects labor requirements. Poor ventilation results in undesirable working conditions and high building maintenance costs. Mechanical ventilation systems are often used to successfully ventilate dairy tie-stall barns. These systems consist primarily of controlled air inlets, fans, and thermostats or other types of controls.