Abstract
•The Tb of TM chicks was significantly lower than those of the controls during TC.•TM chicks had a higher T4 and a lower T3 levels compared with the controls during TC.•TM enhances the Hsp90 and Hsp60 mRNA expression during embryonic and posthatch chicks.•Higher Hsps mRNA expressions were detected in the muscle and heart during TC.•The magnitude of mRNA expressions was tissue- and initial TM duration-dependent.
The effect of thermal manipulation (TM) during embryogenesis (ED 12–18) on mRNA expressions of heat shock proteins (Hsp90, Hsp60 and HSF-1) in muscle, heart and brain tissues during thermal challenge (TC) at post-hatching days 10 and 28 was investigated. Fertile chicken eggs were randomly divided into four groups: Control group (37.8 °C), TM1 (39 °C for 9 h), TM2 (39 °C for 12 h) and TM3 (39 °C for 18 h). At days 10 and 28 of age, chicks in TC groups were subjected to thermal challenge (TC) at 43.0 °C for 6 h while naïve chicks were kept under regular conditions. When compared with the control, TM resulted in a significant increase in mRNA levels of Hsp90, Hsp60 and HSF-1in muscle, heart and brain tissues during embryogenesis and during TC at days 10 and 28 post-hatching. These results indicate a long-term enhancement of Hsp90, Hsp60 and HSF-1 gene expressions associated with improved thermotolerance acquisition in thermally manipulated chicks.