Expression Dynamics of HSP70 Gene in Madgyal Sheep Exposed to Summer Grazing Stress

Abstract

This study investigated how heat stress influences HSP70 gene expression in Madgyal Sheep during grazing in hot weather. The sheep were divided into three groups—A, B, and C—and exposed to direct sunlight for zero, four, and eight hours, respectively. The effects of different heat exposure durations on HSP70 expression were examined on Days 0, 15, and 30. Throughout the experiment, the temperature-humidity index (THI) averaged 76.28±0.81. Results indicated that Groups B and C exhibited higher HSP70 mRNA expression than Group A, with no significant difference between B and C. HSP70 levels increased after 4 hours of heat exposure compared to 8 hours. Initially, HSP70 levels increase to protect cells against heat stress. As heat stress levels rise with prolonged exposure, HSP70 levels also rise, with Group C showing the highest levels. This pattern suggests that sustained heat stress elevates HSP70 to manage physiological stress. The early peak in HSP70 helps protect cells. The marked elevation of both markers in Group B reflects a strong connection between heat stress and the physiological stress response. Overall, there is a positive correlation—higher heat stress correlates with increased HSP70.