Abstract：This experiment was designed to analyse the role of growth axis genes including growth hormore(GH), growth hormore receptor(GHR) and insulin-like growth factor 1(IGF-Ⅰ) during embryonic and post-hatch development in two duck breeds(Gaoyou ducks and Jinding ducks)(Anas platyrhynchos Domestica) with different growth rate. The expression level of GH gene in pituitary tissue and GHR and IGF-Ⅰgene in pectorale muscle and leg muscle were quantified by Real time-PCR on days 13, 17, 21, 25 and 27 of embryonic development, as well as at 7 day post-hatching. The results showed that the mRNA of all the three genes could be detected in the studied tissues in both duck breeds, and relatively similar expression profile was found in the same tissue for each gene. The expression level of GH gene in pituitary increased throughout the embryonic and post-hatch development, and the expression level in Gaoyou ducks was extremely significantly higher than that in Jinding ducks at 7 day post-hatching (P<0.01). In pectoral muscle and leg muscle, the differences of the GHR gene expression between the two breeds at the same development stage were not significant. Within the breed, the expression level of GHR gene in pectoral muscle was significantly lower than that in leg muscle on 13 and 21 embrynic development(P<0.05 or P<0.01), while the expression level of GHR gene in pectoral muscle was significantly higher than that in leg muscle at 25 and 27 embryonic age(P<0.05 or P<0.01). The expression level of IGF-Ⅰgene in pectoral muscle in Gaoyou ducks was higher than that in Jinding ducks except for 27 embryonic age, and the differences were significant on 13, 21 embryonic development and 7 day post-hatch(P<0.05 or P<0.01). The expression level of IGF-Ⅰgene in leg muscle of Gaoyou ducks was higher than that of Jinding ducks at different development stage, but the difference was not significant(P>0.05). Within the same breed, the expression level of IGF-Ⅰgene in pectoral muscle was significantly higher than that in leg muscle except for 13 embryonic age(P<0.05 or P<0.01). In conclusion, these three genes may have an important roles in the early growth and development of ducks, and they have evidently spationtemporal expression pattern, meanwhile, the expression of GH and IGF-Ⅰ genes is also affected by breed.
