Effect of tunnel ventilation and evaporative cooling on the barn enviroment and cow comfort in midwest dairy facilities

摘要

During the summer of 2001 six tunnelventilated tie stall barns in northeastern Missouriand southeastern Iowa were evaluated.Three of the barns were equipped with celluloseevaporative pads and three were not.Temperature and relative humidity were recordedcontinuously for 11 weeks from July 1to September 15, 2001. Cattle housed in tiestall barns equipped with evaporative coolinghad lower average respiration rates (65.7 vs70.3 breaths/min) than those housed in barnswithout evaporative cooling. However, ratesobserved in the morning and at night were notdifferent, only the afternoon rates differed significantly.Average rectal temperatures werealso lower for the cows housed in evaporativecooled barns. Similar to respiration rates, thegreatest differences existed during the afternoon.Skin temperatures followed respirationrates and rectal temperatures and were significantlylower for the cattle housed in the barnsequipped with evaporative cooling with thegreatest differences observed during the afternoon.Barns equipped with evaporative coolingpads were up to 8.25ºF cooler during the afternoonhours than those without. However,relative humidity increased up to 30% andTHI decreased up to 3.25 units over ambientconditions. As compared to the barns withonly tunnel ventilation, barns with evaporativecooling had a greater percentage of July andAugust hours at a THI level below 70 andeliminated the hours in the 85-90 THI levelduring the hours of 1:00 PM and 8:00 PM.Evaporative cooling reduced the heat stressduring the afternoon hours without increasingthe stress during the evening and night hoursas compared to the tunnel ventilated barns.This study showed significant advantages forthe evaporative cooled and tunnel ventilatedbarns in terms of respiration rates, rectal temperaturesand barn environment.