Effect of thermal manipulation during embryogenesis on gene expression of myogenic upstream activation factors pre- and post-hatch in broilers

Abstract

This study aimed to determine the optimum timing of embryonic thermal manipulation (TM) that may result in improvement of mRNA expression of myogenic upstream activation factors viz. Wnt family member-3 (Wnt-3), sonic hedgehog gene (Shh), proliferating cell nuclear antigen (PCNA) and paired-box transcription factor-7 (Pax-7) during development and histogenesis of broiler muscle. Fertile eggs (1440) were divided randomly and equally into 5 treatment groups including control (no TM) and four treatment groups (TM1, TM2 TM3 and TM4) that were daily subjected to 39 ̊C for 18 h with 65% relative humidity during embryonic days ED 7–11, ED 11–15, ED 15–18 and ED 7–18 respectively. Pectoral and thigh muscle mRNA expressions of myogenic upstream activation factors were evaluated by semi-quantitative real-time RT-PCR. Out of TM conditions that were investigated, TM1 resulted in a significant improvement of Wnt-3, Shh, PCNA and Pax-7 expressions in broiler pectoral and thigh muscles during embryonic and post-hatch life when compared to the control. Thus, thermal manipulation during early embryongenesis (embryonic days ED 7-11) enhance broiler skeletal muscle myoblast proliferation by triggering and inducing transcription factors that regulates myogenesis and subsequently may lead to improve cell number and size of skeletal muscle. The outcome of this study indicates that TM during ED7-11 improved muscle response to heat stress, was safe to the pectoral and thigh muscles and this method may enhance myogenesis and muscle growth in a positive manner.

Keywords

• Broiler, Myogenesis, Paired-box transcription factor-7, Sonic hedgehog, Thermal Manipulation, Wnt family member-3