Thermal performance of a low-profile cross-ventilated freestall dairy barn with evaporative cooling pads in a hot and humid climate.

A commercial low-profile cross-ventilated system (LPCV) free-stall barn with evaporative cooling pads on the air intake side was used to assess the potential of cross-ventilation with evaporative cooling to alleviate heat stress in lactating dairy cows. A total of 5712 records (238 days × 24 h) of air temperature (AT) and relative humidity (RH) values were collected. In order to state the effectiveness of the ventilation system and potential heat stress, the temperature humidity index (THI) and enthalpy (h) were calculated outside and inside the LPCV barn. The cooling capacity of the LPCV system is greater in conditions of low humidity, and the difference between the values of the internal and external temperature reached -12 °C. The LPCV reduced exposure to heat stress, increasing the time cows spent in thermoneutral conditions. This system could reduce the occurrence of temperature above 25 °C from 33 to 5% and 11% in sections A (represents the inlet side of the barn) and D (represents the outlet side of the barn), respectively. On the other hand, the LPCV kept a high and constant rate of RH throughout the day. The average inside and outside AT were significantly different, but differences in temperature were observed across the width of the barn. Analyzing the barn by the indexes, the THI showed that the barn promoted cows more time confined under non-stressful thermal conditions (between 83.8 and 90% vs 68.7%) and stress period much lower compared to the external environment (between 10 and 16.2% vs. 31.3%). The enthalpy index showed that there was not much difference between the internal and external environments. The LPCV system is another installation alternative for raising dairy cow in a hot and humid climate.