Association of insulin-like growth factor-I (IGF-I) gene polymorphism with serum IGF-I concentration and body weight in Korean Native Ogol Chicken

IGF-I is involved in the regulation of growth and differentiation in mammals. but its role as a modulator of growth and metabolism in poultry is poorly understood. And. no studies have so far been reported for the comparison between serum IGF-I concentration and body growth in the egg type or the dual purposes (meat and egg type) chicken including the Korean Native Ogol Chicken (KNOC). Therefore. in order to improve the body growth and meat production or the KNOC. this study was conducted for the identification of the polymorphism of IGF-I gene and for its possible association with both body weight and IGF-I concentration. The RFLP patterns for IGF-I gene were identified by the PstI restriction enzyme. The frequencies of +/+. +/-,and -/- genotype were 16.9%. 51,7%. and 31.4%. respectively. Any statistical significance was not observed in all variations except for sex: variation (p <0.01) by covariate quadratic model. The significant effect of the IGF-I genotype on body weight by sex indicates that there are different physiological characteristics in gender. Although the bodS weights of male KNOCs in most ages were not significant, there was a tendency of KNOCs with +/+ IGF-I genotype to be heavier than those with any other genotypes. But all IGF-I genotypes in female did not influence on body weight. The ANOVA revealed no significant effects of IGF-I genotypes on serum IGF-I concentration but sex effect was highly significant on the IGF-I concentration at 20 and 30 weeks (p <0.01), Although the +/+ genotype, in gender. tended to express a higher IGF-I concentration than the other genotypes at all ages in malts. a statistical difference among the genotypes was not found except for 60 weeks (p <0.05). Furthermore. since body weight and IGF-I genotypes are associated, it is possible to improve KNOC to a meat type breed if a continuous selection can be made for the body weight and/or IGF-I traits.