Relationship Between Expression Of Growth Related Genes And Growth Performance In Langshan Chicken

The attempt has been made to better understand the profile of growth and development and the relationship between gene expression of growth related genes and growth performance in Langshan chicken. Taking AA broiler as control, we measured the body weight and body size of different period and analyzed the difference in chick's growth. Using quantitative PCR, we determined growth related gene expression in mRNA level and analyzed the relationship between the differences of gene expression and growth performance. The results showed that,The average body weights of Langshan chickens at Day 1, Day 10, Day 3 0, and Day 60 were significantly lower than that of AA chickens of the same ages. The average daily gain of Langshan chickens from Day 30 through 60 was significantly lower that of AA broilers.Langshan chickens showed faster growth in body length, sternum length and metatarsus length before Day 60 than that after Day 60 while the growth of chest breadth reached another growth peak from Day 60 through the Day 90. It has found that the increases of the body length, sternum length of Langshan chickens were faster than that of AA broilers while the increases of metatarsus length and chest breadth of Langshan chickens were slower than that of AA broilers.The lowest expression of GHR mRNA was in the Day 10 in both Langshan chicken and AA broilers.GHR mRNA expression in Langshan chickens reached the highest level at the Day 30 while this peak appeared at the Day 60 in AA broilers. The lowest expression of IGF-1 mRNA occurred at Day 1 and Day 10 but this expression increased significantly after the Day 30 and reached its peak before the Day 60 in both Langshan and AA birds.During the whole experimental period, the expression level of GHR mRNA in Langshan chickens was lower than that of AA chickens, and there was a significant difference in Day 1 and Day 10 (P<0.05). This variation profile was coincidant with that of body weight. So we considered it was the different in GHR mRNA that caused the difference at body weight in Langshan and AA chicken.IGF-1 mRNA expression in liver in Langshan chickens at Day 1 and Day 10 wassignificant lower that in AA broilers (P<0.05 ) . However, IGF-1 mRNA expression in Langshan chickens at Day 30 and Day 60 was significant higher that in AA broilers (P<0.05) .MSTN mRNA expression increased with the age increasing in both breeds. IGF-1 mRNA expression profiles were different in the two breeds. IGF-1R mRNA expression in Langshan chickens was low at and before Day 30, and it increased significantly at Day 60; in AA chickens the highest expression levels were seen at Day 1 and Day 30 and two valleys were seen at Day 10 and Day 60. There was no significant variation of myf5 mRNA expression in all experimental stages in Langshan chickens but the expression was seen higher at Day 1 in AA broilers than that of other periods.MSTN mRNA expression level at 1st day in Langshan chickens was 43.1 % (P<0.05 ) higher than that of AA chickens(P<0.05) and from DaylO through Day 60 its expression level in Langshan chicken was lower than that of AA chicken, with the differences being significant at Day 10 and Day 30.The expression level of myf5 mRNA at Dayl in Langshan chicken was 28.3 % lower than that of AA chicken (PO.01) and at Day 10 that was reversed. At Day 30 and Day 60, no significant difference was found in its expression level between the two breeds.The expression level of IGF-1 mRNA was lower in Langshan chickens than that in AA chickens before Day 30, being significantly different at Day 10( PO.01) . However at Day 60, its expression level in Langshan chickens was significantly higher than that of AA chickens.No significant difference was seen of IGF-1R mRNA expression level at Dayl and Day 30 between the two breeds. IGF-1R mRNA expression level at DaylO and Day 60 in Langshan chickens was significantly higher than that of AA chicken (P<0.01) .