Thermal environment in mobile shelters with different cover types used for chicken housing at the semi-extensive rearing system

摘要

In tropical climate countries, animal production faces a huge challenge, being the high solar irradiation levels an important factor that negatively influences the welfare and animal performance. The purpose of this research was to check the environment inside mobile shelters with different kinds of cover materials. This research has been developed at the State University of Goias, Brazil, being used four different cover materials: DFPC, double-faced plastic canvas; PVC, polyvinyl chloride; VFB, tiles made with vegetable fiber and bitumen; and VFBW, tiles made with vegetable fiber and bitumen being the outer face painted white. Covers were placed up mobile shelters with the following dimensions: 1 m length x 1 m width x 1 m height and cover pitch of 30 degrees. The environment was evaluated through thermal comfort indexes: enthalpy (H), temperature and humidity index (THI), black globe and humidity index (BGHI), mean radiant temperature (MRT) and thermal heat load (THL), and the measurement of thermal environmental variables (temperature of external (EST) and internal (IST) surface of the cover, dry bulb temperature (T-db), black globe temperature (T-bg), relative humidity (RH), and wind speedy (WS)). Data analysis was performed using PROC MIXED of SAS (R) by analysis of variance (ANOVA), followed by the Tukey test, at 5% of significance level. There was observed beneficial effect of the usage of shading, with a decrease in air temperature and thermal comfort indexes when compared with the unshaded environment. The materials presented different thermal behavior, with better results for PVC and VFBW, that presented lower internal (IST) and external surface temperature (EST), in addition to lower black globe temperature, thermal heat load, and black globe and humidity index. PVC and VFBW were the best types of covers evaluated, with significant decreased thermal comfort indexes.