|
There are considerable evidences that endocrine factors are involved in the development and differentiation of ovary in the poultry. However, the effects of IGF-1 and steroid hormones on the sexual maturity of Korean Native Ogol Chicken (KNOC) have not yet been studied. Therefore, this study was performed to examine the expression of endocrine factors (IGF-I, estradiol, and progesterone) in KNOC and to find relationships between serum concentrations of these and the sexual maturity. Serum IGF-1, estradiol, and progesterone concentrations were measured by radioimmunoassays. Based on IGF-1 PCR-RFLP patterns. chickens were divided into three groups, that is. AA. AB, and BB genotypes. Compared with the AA and AB genotypes. the BB genotypes layed the first egg at a younger (P$lt;0.05) age. Moreover. progesterone concentration at 20wk of age before the sexual maturity was greater (P$lt;0.05) in the BB genotype than in the AA and AB genotypes. Although a significant difference in estradiol concentration between the three genotypes was not detected. the BB genotype tended to have a greater concentration of this hormone than the AA and AB genotypes. On the other hand, IGF-1 concentration was greater in the AA and AB genotypes than in the BB genotype. Concentrations of IGF-1. estradiol, and progesterone were negatively correlated with the age when the bird first layed an egg in the AA genotype. Taken together, the results suggest that the sexual maturity in KNOC is likely to result from complex interactions of several endocrine factors.
|