What question did this study set out to answer?

The study evaluates the physiological and environmental responses of sheep under different management systems during heat waves.

May 22, 2026Open Access

Effects of heat wave on physiological and environmental responses of sheep managed in different systems in Eastern Amazon assessed by infrared thermography

Key Points

The study evaluates the physiological and environmental responses of sheep under different management systems during heat waves.
Conducted over 187 days during less rainy and transition periods.
Twenty female Santa Inês sheep randomly assigned to traditional (n=10) and silvopastoral (n=10) systems.
Physiological and thermographic data collected monthly at four different times using a scientific thermographic camera.
Body temperature in traditional system was significantly higher at several body regions (p<0.0001).
Soil temperature was 55.7 °C in traditional system compared to lower temperatures in silvopastoral system (p<0.0001).
Respiratory rates rose by 28% in the traditional system at noon, indicating higher heat stress.

Abstract

Infrared thermography is a non-invasive tool widely used to detect heat stress in farm animals under tropical conditions. This study aimed to evaluate physiological and environmental responses of sheep managed under traditional and silvopastoral systems in the Eastern Amazon using infrared thermography. The study was conducted over a period of 187 days, encompassing the less rainy and transition periods. Twenty female Santa Inês sheep, aged 10–18 months and weighing 37.19 ± 6.17 kg, were evaluated monthly at 06:00, 12:00, 18:00, and 00:00 h using physiological, environmental, and thermographic measurements, and were randomly assigned to two groups: Traditional System (TS – n = 10) and Silvopastoral System (SP – n = 10). Both had the same pasture, as well as access to water and mineral salt ad libitum . Measurements were taken with a scientific thermographic camera, and the data were analyzed with 5% significance in the Statistical Analysis System (SAS) software. There was a difference between the thermal windows evaluated in the animals' body regions: head (TS – 38.7 °C and SP – 37.8 °C), armpit (TS – 38.9 °C and SP – 38 °C), back (TS – 39.5 °C and SP – 38 °C), flank (TS – 38.6 °C and SP – 38.1 °C), and rump (TS – 39.2 °C and SP – 37.6 °C) ( p < 0.0001). Difference was observed between the soil temperature (55.7 °C) and the forage temperature (39.1 °C) within the TS ( p < 0.0001). In contrast, a difference was noted in the trunk (35.8 °C), canopy (33.5 °C), and soil (39.1 °C) regions in the SP ( p < 0.0001). It was concluded that the SP promoted lower body and environmental temperatures compared to the TS, indicating improved thermal comfort for sheep managed in the SP. • Shading reduced the soil temperature by up to 16.6 °C, mitigating extreme heat stress. • BTCI indicated lower thermal adaptation in the TS, especially at 12 pm. • Thermography revealed a distinct thermal gradient between the canopy, trunk, and soil. • RR rose 28% in the TS at 12 pm., indicating greater respiratory overload. • RT at TS at 12 am., suggested thermal retention even at night.

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