LAUSR

ABSTRACT Insulin-like growth factor II (IGF-II) is one of the members of the somatotropic axis which controls the growth and development of animals. This study was conducted to identify single-nucleotide polymorphisms in the IGF2 gene and study their associations with two production traits in a Chinese indigenous chicken (Langshan chicken) population. Genetic variants within the IGF2 gene were screened through PCR-SSCP and DNA sequencing methods. A C6707G mutation (Chromosome 5 position 13,161,038 build 4) was identified. Associations between the mutations of the gene with two production traits were analysed. The results showed that individuals within the GG genotype had significantly higher 16-week-old body weight than those within the CG genotype. In addition, the GG individuals also had significantly higher 300 days egg numbers than individuals within CC or CG genotype. Ratios of dominance effects to absolute values of additive effects were less than 0 for both traits implying that Langshan chickens with homozygous genotypes for this locus had higher performance than individuals with heterozygous genotypes.