Insulin-like growth factor Ⅱhas profound effects on the growth and differentiation of animal embryo. Some researches indicated that it affects the fat metabolism of poultry. This study was designed to investigate the effect of IGF2 on chicken fatness traits. Broiler, Hyline Brown layer and three native breeds (Shiqiza, Beijing You, Baier) were used in this research. Body weight and body composition traits were measured in broiler line at the age of 7 weeks. Primers for exon2 in IGF2 were designed from database of chicken genomic sequence. Polymorphisms were detected by PCR-SSCP and DNA sequencing. The total χ2 test results showed that there was a significant difference (P < 0.01) in the frequency of genotype among breeds. A C/G mutation at base position 139 was found among individuals in broiler line and the least square analysis showed that BB genotype birds had significant lower (P <0.05) abdominal fat weight and percentage of abdominal fat than AA or AB genotype birds. From the results we can conclude putatively that IGF2 gene is the major gene affecting the fatness traits of chicken or it links with the major gene, and the mutation could be used as the molecular genetic marker to select the chicken for low abdominal fat.
