Spatiotemporal variations on infrared temperature as a thermal comfort indicator for cattle under agroforestry systems

With the expanding use of thermal assessment techniques in beef cattle, infrared thermography has become a promising tool for assessing the environment for animal thermal comfort. Goals of this study were: (1) to evaluate cattle thermal comfort in agroforestry systems with different shade availability (2) to verify the spatiotemporal variations of infrared temperature inside agroforestry systems, and; (3) to test infrared ther-mography as a potential tool to assess animal thermal comfort indices in agroforestry systems. A trial was carried out between June 2015 and February 2016, covering Central-Brazil's dry winter and rainy summer seasons, respectively. The experimental area of Embrapa Beef Cattle is located in Campo Grande (Mato Grosso do Sul), coordinates 20 degrees 24'53 '' S, 54 degrees 42'26 '' W and 558 m altitude. The 12 ha plot has two agroforestry systems varying shade availability. Traditional Black Globe Temperature and Humidity Index, Heat Load Index and Radiation Thermal Load were determined, from measurements using digital thermo-hygrometers, with datalogger. Surface temperature and humidity of tree canopies and pasture were determined using an infrared thermographic camera. Results show spatiotemporal variations in infrared temperature. This means that the environment inside agroforestry systems is not homogeneously comfortable for cattle, and the system with the lowest shade avail-ability has the greatest heat accumulation area. Weak to strong associations were identified between infrared variables and thermal comfort indices (0.08 = r <= 0.75). Positive relationships were also obtained and equally well explained by the Black Globe Temperature and Humidity Index and Heat Load Index (0.55 = R-2 <= 0.94). We conclude that infrared thermography can be used as a tool to assess thermal comfort indices in agroforestry systems and to determine onset of animal thermal stress from environment and heat body accumulation.

Automated summary

The study evaluated cattle thermal comfort in agroforestry systems, verified spatiotemporal variations of infrared temperature, and tested the potential of infrared thermography as a tool for assessing animal thermal comfort indices in agroforestry systems. Results showed that the environment inside agroforestry systems is not uniformly comfortable for cattle, with the system having the lowest shade availability accumulating the most heat. Weak to strong associations were identified between infrared variables and thermal comfort indices, demonstrating the utility of infrared thermography in assessing thermal comfort indices and onset of animal thermal stress.