Abstract：This experiment was designed to study the effects of polymorphism of growth differentiation factor 9 gene (GDF9) on egg production traits in female line of Shaobo chicken(Gallus domesticus), and 216 female line of Shaobo chicken breeding in Poultry Institute, Chinese Academy of Agricultural Sciences were used in the present study. The genetic polymorphism of GDF9 was investigated by PCR-RELP, and analyze the association of polymorphisms sites with egg production traits in female line of Shaobo chicken, which included age at first egg (AFE), body weight at first egg, weight at first egg (WFE), average egg weight at 300 days (AWEN) and the total number of eggs at the age of 300 days (EN). The results indicated that three SNPs site were detected in exon2 of GDF9 gene. Three genotypes(AA, AG and GG) were found at G2051A mutation locus，two genotypes(CT, TT) were found at T2273C mutation locus, three genotype(CC, CT, TT) were found at C2336T mutation locus. The fitness test showed that all Shaobo chicken at three mutation locus were in Hardy-Weinberg equilibrium. The relationship between GDF9 gene and reproduction traits in female line of Shaobo chicken was analyzed by least squares linear model. The individuals with GG genotype had significant lighter weight at first egg (P<0.05), GG genotype birds had also significant more the total number of eggs at the age of 300 d (P<0.05). Least squares means of reproduction traits for TT was not significantly lower than that for CT (P>0.05) at T2273C mutation locus. CT genotype birds had significant younger age at first egg (P<0.05), the individuals with CT genotype had also significant more the total number of eggs at the age of 300 d (P>0.05). The combine genotypes also had significant genetic effects on age at first egg (AFE), weight at first egg (WFE), body weight at first egg (BWFE) and the total number of eggs with 300 days (EN). However, it seemed that the effect of GDF9 gene with combine genotype on egg production traits was more significant. The results indicate that polymorphisms of GDF9 gene are significantly correlated with egg production traits in female line of Shaobo chicken, and individuals with GGCTCT combine genotype can be used as the molecular genetic marker to select female line of Shaobo chicken for reproduction traits.
