Abstract: 【Objective】The objective of this study was to discuss developmental changes of gene expression of myostain (MSTN) and myogenin (MyoG) and their association analysis with carcass traits , and the relationship of the expression level between MSTN gene and MyoG gene in Hu sheep. 【Method】The developmental changes of gene expression of MSTN and MyoG on the early growth of Hu sheep were detected by RT-PCR analysis.【Result】MSTN gene expression in muscle of Hu sheep was the lowest at 2 days old, and tended to increase with the increasing age before 60 days, but after 60 days tended to decrease with increasing age. The MyoG gene expression in muscle of male sheep was the lowest at 2 days old, and tended to increase with the increasing age before 30 days, and after 30 days the expression first tended to decrease before 120 days(for male)or before 90 days (for female), and then tended to increase with the increasing age. Among most of different stages there were significant differences or extreme significant difference for MSTN and MyoG gene in males and females of Hu sheep. There was a significant or extremely significant difference between male and female in most of different stages. The expression level of the MSTN and MyoG genes all showed a positive correlation with liveweight, carcass weight and net meat weight, but only MSTN showed a significant relationship with net meat weight (0.01＜P＜0.05). MSTN gene showed an extremely significant positive relationship with MyoG.(P＜0.01). 【Conclusion】The age and gender played a very important role in the expression of sheep muscle. MSTN and MyoG genes showed a similar variation pattern for the male and female. Both of MSTN and MyoG gene expression in muscle of Hu sheep did not always tend to increase or decrease with the increasing age. MSTN gene showed an extremely significant positive relationship with MyoG gene on the early growth of Hu sheep.

Key words: Hu Sheep, myostatin, myogenin, gene expression, muscle trait