Abstract: Using quantitative PCR investigate myostatin (MSTN) gene expression levels in different time of Yemnle sheep's muscle and fat (0 to 6 month), using 2^－ΔΔCt analysis of the different expression levels in different time, and aimed to understand the expression levels of Yemule sheep MSTN gene, provided genetic information for the selection of muscle growth traits. The results showed that MSTN gene expression levels in 3 month was significantly higher than the others months (P<0.05), and the others months had no significant differences in the muscle (P>0.05). In the fat , the expression level of MSTN gene present was lower in 0 month, With the growing increase, the expression levels in MSTN gene has increased, and MSTN gene expression levels was the highest in 5 month, then with the growing increase, the expression levels in MSTN gene had decreased. With the growing increase, MSTN gene expression levels had some certain rules, provided scientific basis for the selection of muscle growth traits.

Key words: Yemule sheep; MSTN gene; gene expression