Evaporative cooling of cows in a nonhomogeneous temperature field

Drifts of water were spread on the cow body surface at a stable temperature of 25 degrees C. Approximately after 3.5 minutes the ventilation of cool a ir (at the temperature of 22 degrees C and the relative humidity of 60%, 1. 6-1.8 m/s) started either on lumbar or shoulder part of the body for the pe riod of 30 minutes. The surface temperatures of the cow body were screened by an infra-red spectrum camera and consequently evaluated on the body part s most exposed to cool air. Six points of time were determined for screenin g: the Ist for time before the beginning of evaporation cooling, the 2nd fo r 3.5 minutes after the beginning of drift water spreading (beginning of ai r-ventilation), then after 10, 20 and 30 minutes (end of air ventilation), and still 3.5 minutes after the end of this air-ventilation. Conclusions of this infra-red screening were: the method of evaporative cooling decreased the body surface temperature by 3 K during 3.5 minutes. The consequent air -ventilation caused cooling down by 5 K during 10 minutes (at shoulder part exposition) and by 6 K (at lumbar part exposition), respectively. After 10 minutes of the air-ventilation the process of cooling down stopped and an opposite process began, that means the process of warming up, even if the b ody surface was still cooled down on one of the exposed parts. This trend m ight lasted even after the 30th minute of the air-ventilation.