Characterization of Thermal Patterns Using Infrared Thermography and Thermolytic Responses of Cattle Reared in Three Different Systems during the Transition Period in the Eastern Amazon, Brazil.

Simple Summary: This study aimed to characterize the thermal patterns of cattle raised in three different production systems during the transition period in the eastern Amazon, Brazil, using infrared thermography and by evaluating thermolytic responses. The evaluated systems were silvopastoral (with shade and no access to the bathing area), traditional (without shade and with no access to the bathing area), and integrated (with access to the shade and the bathing area). The thermographic images showed that the silvopastoral system, with shading, provided more favorable thermal conditions compared to the other systems. Physiological analyses revealed that the cattle maintained a rectal temperature within normal ranges in all systems. However, the respiratory rate was higher in the traditional system, indicating possible thermal stress in this environment. The thermal comfort indices indicated moderate stress conditions at times of greater solar intensity in all systems. In general, the results suggest that the silvopastoral system offers better thermal conditions for cattle, providing shade and reducing thermal stress. Thus, management practices aimed at animal welfare and productivity in production systems in the eastern Amazon region can be adopted by ranchers. In the Lower Amazon mesoregion, there are basically three types of production systems: the traditional (without shade and no bathing area), the silvopastoral (with shade and no bathing area), and the integrated (with shade and bathing area). It is considered that the type of production system influences the thermal comfort and productivity of cattle, so this research aims to evaluate the influence of these three types of production systems on the thermoregulation of Nellore cattle. The experiment was carried out on a rural property for raising cattle, located in Mojuí dos Campos, Pará, Brazil, during the transition period (June/July). Thirty bovine males (not castrated, aged between 18 and 20 months, average weight of 250 ± 36 kg, body condition score of 3.5, clinically healthy) were randomly divided into three groups: Silvopastoral System—SS (n = 10), Traditional System—TS (n = 10), and Integrated System—IS (n = 10). Climate variables were collected (air temperature (AT °C), relative humidity (RH %), wind speed (WS, m/s), solar radiation (SR), black globe temperature (BGT °C), and physiological parameters, such as respiratory rate (RR) and rectal temperature (RT)) at 6 a.m., 12 p.m., 6 p.m., and 12 a.m. to determine the thermal comfort situation of the animals. Thermographic images of the environment and animals were captured in order to obtain the body surface temperature (BST) through infrared thermography. The Benezra Thermal Comfort Index (BTCI), Environmental Stress Index (ESI), Equivalent Temperature Index (ETI), and Iberian Heat Tolerance Index (Iberian HTI) were used. The results showed that the silvopastoral system, with shading by chestnut trees and an ample vegetative area, presented better thermal conditions, with an average of 28.98 °C, in comparison with the traditional system (35.93 °C) and the integrated one (34.11 °C). It was observed that the body surface temperature of cattle did not differ significantly between the anatomical regions of the body and the studied systems (p > 0.05). As for the respiratory rate, the traditional system registered higher values, with an average of 41 movements per minute, indicating possible thermal stress (p < 0.05). The thermal comfort indices revealed that all systems presented moderate stress conditions during times of higher solar intensity. It is concluded that the silvopastoral system proved to be more favorable for cattle, providing shade and reducing thermal stress, which may have a positive impact on animal welfare and productivity in this region. [ABSTRACT FROM AUTHOR]