Abstract: 【Objective】The objectives of the present study were firstly to detect polymorphisms in the growth differentiation factor 9 (GDF9) gene, and secondly to investigate the association between GDF9 gene and high prolificacy in Jining Grey goats. These results will provide a scientific basis for marker-assisted selection for high prolificacy in goats.【Method】The GDF9 gene which controls the fecundity of Belclare and Cambridge ewes was studied as a candidate gene for the prolificacy in Jining Grey goats. According to the sequence of ovine GDF9 gene, four primer pairs were designed to detect single nucleotide polymorphism of exon 2 of GDF9 gene in both high fecundity goat breed (Jining Grey goat) and low fecundity goat breeds (Boer goat, Wendeng dairy goat, Liaoning Cashmere goat, Beijing native goat) by PCR-SSCP. 【Result】The results indicated that the homology of nucleotide sequence of exon 2 of GDF9 gene between goats and sheep was 99 percent. The products amplified by primer 1 and primer 4 displayed polymorphism. For primer 1, three genotypes (AA, AB and BB) were detected in all five goat breeds. The sequencing results indicated that there was one single nucleotide mutation (G26→A26) at exon 2 of GDF9 gene in goats, but this mutation did not cause amino acid change. Frequency of allele A was 0.9128, frequency of allele B was 0.0872 in Jining Grey goats. The does with genotype AA had 0.54 (P<0.01) or 0.63 (P<0.01) kids more than those with genotype AB or BB in Jining Grey goats, respectively. For primer 4, three genotypes (CC, CD and DD) were detected in all five goat breeds. The sequencing results showed that there was one single nucleotide mutation (G792→A792) at exon 2 of GDF9 gene in goats, and this mutation resulted in an amino acid change: valine→isoleucine. Frequency of allele C was 0.9266, frequency of allele D was 0.0734 in Jining Grey goats. The does with genotype CC had 0.57 (P<0.01) or 0.62 (P<0.01) kids more than those with genotype CD or DD in Jining Grey goats, respectively.【Conclusion】These results preliminarily showed that the GDF9 gene is either a major gene that influences the prolificacy in Jining Grey goats or a molecular marker in close linkage with such a gene.

Key words: Goat, Prolificacy, Growth differentiation factor 9 gene, PCR-SSCP