Abstract
A total of 1,440 fertile eggs were divided randomly and equally into 5 treatment groups; control (no TM) and 4 treatment groups: TM1, TM2, TM3, and TM4 that were thermally subjected to 39 degrees C for 18 h with 65% relative humidity daily, during embryonic days ED 7-11, ED 11-15, ED 15-18 and ED 7-18, respectively. Out of TM conditions that were investigated, TM1 resulted in a significant improvement in expression of myogenic factor-5 (Myf5), myoblast determination protein (MyoD) and myogenin (MyoG) in pre and post hatch broiler muscle when compared to the control. This study aimed to determine the optimum time for thermal manipulation during embryogenesis that may result in improvement in expression of myogenic regulatory factors (MRFs): Myf5, MyoD, MyoG and myostatin (MSTN) in broiler muscle. Thus, the results of this research may provide a means of improvement of myogenesis of pectoral and thigh muscles of broilers proceeding from early embryogenesis (ED7) through post-hatch day.