Abstract: The experiment was carried out to investigate the MSTN gene expression in muscle tissues and its association with growth indexes in 1-6 months old Kazak lamb,and provide genetic information for breeding Kazak lambs.Five Kazak lambs were randomly chosen and leg muscle samples were collected monthly.Body length,body height,body weight,pipe circumference and chest circumference were measured.MSTN gene relative expression levels in 1-6 months old Kazak lamb muscle tisses were determined using Real-time PCR and its association with growth indexes were analysised.The results showed that: Kazak lambs grew rapidly at the age of 1 and 2 months.From 4 months,body weight increased slowly and body length,body height and chest circumference rose slowly meanwhile pipe circumference stopped growing from 3 months.At 5 and 6 months,the growth indexes had not significant difference (P>0.05).MSTN gene expression had not significant difference in 1-4 months old Kazak lamb muscle tissues (P>0.05),showing a upward trendency.The expression was the highest at 5 months and lowest at 6 months.MSTN gene expression was significant negatively associated with body length (P<0.05) and the correlation coefficient was-0.472.And there was a weak negative association between MSTN gene expression with body weight and chest circumference,a weak positive correlation with body height and pipe circumference.

Key words: Kazak lamb; MSTN gene; expression; correlation analysis