Respostas comportamentais de novilhas leiteiras confinadas submetidas ao sistema de resfriamento adiabático evaporativo

The research aimed to evaluate the influence of evaporative cooling system (AECS) on the behavioral variables of Holstein dairy heifers kept in confinement. Twelve heifers were used, divided into three treatments: 1) ventilation and fogging by AECS when the temperature reached 25°C at any humidity, 2) ventilation and fogging by AECS when the temperature reached 25°C with relative humidity less than or equal to 70% and, 3 without cooling system. The experimental design consisted of a latin rectangle repeated twice. The environmental variables (dry bulb temperature), black globe temperature and relative humidity were collected daily through dataloggers throughout the experiment. In behavioral analysis were observed postures (standing and lying), the activities of the animals and the places where they were in the pen, in 15 minute intervals. However, there was no difference in the behavioral variables of animals between treatments.