Cooling Effect of Fabric Air Ducting System for Loose Housing Dairy Cows in an Open-Sided Barn

摘要

Curtain-sided bams with circulation fans above stall are commonly used to house dairy cows in China.Many of the circulation fans currently used are unable to provide appropriate cooling, especially for the naturally ventilated shed, and can result in decreased feed intake and milk production.Designed for alleviating heat stress and improving animal comfort, a system consisting of an air cooler and a 30 m fabric air duct (FAD) was integrated to evenly distribute cooling air to targeted zones above stall beds.The system was evaluated in an open sided dairy barn in Tianjin, China.For the stalls equipped with FAD system, air velocity reached 1.1 m/s and higher at the 0.7 m height plane of the stall space, and was more uniformly distributed.Compared to the stalls equipped with only circulation fans, the FAD system lowered air temperature by 1.5 ℃, and increased relative humidity by 8.1％.On average, Temperature Humidity Index (THI) and Equivalent Temperature Index (ETI) were decreased by 0.5 and 0.6,respectively.After a 15-day operation of the system, rectal temperatures of the treated dairy cows were significantly lowered (P ＜ 0.05).The result also showed that the treated group had higher milk production.These findings suggest the FAD can be an effective cooling alternative for naturally ventilated dairy barns.