Infrared thermography for evaluation of the environmental thermal comfort for livestock.

The objective of this study was to assess the use of infrared thermography as a microclimate-evaluating tool and an estimate of the thermal comfort provided by four types of tree to cattle under grazing conditions in the central region of Brazil. The experiment was conducted at the Embrapa Beef Cattle Company, in Campo Grande, MS, Brazil, from June to August 2015. Evaluations were carried out over four consecutive days, at 1-hour intervals, from 8:00 a.m. to 4:00 p.m. (local time; GMT - 4:00). Infrared thermography images of tree crowns and soil surface underneath them from the shadow projection of four tree species native to the Brazilian cerrado (savannah-like) biome were obtained. The microclimate was assessed by estimation of thermal indices: temperature and humidity index, black globe, and radiation thermal load. The previous was calculated based on records of air temperature, dew point temperature, black globe temperature, air relative humidity, wind speed, and solar radiation. The geometrical settings of the trees were assessed for each tree component. Five thematic groups were formed based on multiple factor analysis that summarizes three synthetic analytical dimensions to explain the total variance among the studied elements and the existing correlations between groups. Positive linear correlations were found between thermography and the temperature measurements, thermal comfort indices, and radiation, suggesting that infrared thermography can be used as a tool for estimating and monitoring the microclimate and thermal comfort, presenting a potential use of measurement in agroforestry systems.