THE RELATIONSHIP BETWEEN AGE AT SEXUAL MATURITY AND SOME PRODUCTIVE TRAITS IN LOCAL CHICKENS STRAIN

A total of 250 females of Alexandria chickens from egg line which selected for age of sexual maturity were divided into three groups according to their age at sexual maturity trait (X ± one unit of S.D.), as early sexual maturity (ESM) averaged (128.5 d), medium sexual maturity (MSM) averaged (152.8 d) and late sexual maturity (LSM) averaged (166.6 d). The objectives of this study were to determinate the relationship between age at sexual maturity and each of growth and egg production traits and to estimate genetic and phenotypic correlation coefficients between age at sexual maturity and studied traits. Results showed that, there were significant differences of body weight at 4 wks (202.2, 187.4 and 177.5 gm.) and at 8 wks (560.6, 502.8 and 479.0 gm.) for ESM, MSM and LSM, respectively. However, there were no significant differences of body weight at hatch day (BW0) and at sexual maturity (BWM) among these groups. These results showed that the early age at sexual maturity group had the heaviest weight till 8 weeks of age, which was not found at sexual maturity. Early age at sexual maturity group gave the highest egg number during the first 90 days after sexual maturity (42.6 eggs) compared with MSM and LSM groups (28.2 and 30.6 eggs, respectively). Also, egg mass during the first 90 days after sexual maturity was the highest value (1405.8 gm.) for early maturity group; in the meanwhile the average of egg weight was the lowest value (33.0 gm.). The genetic and phenotypic correlations of age at sexual maturity were negatively with all of body weight at 4-wk, 8-wk of age, egg number and egg mass, while they were positive with egg weight. Therefore, breeding programs aiming to reduced age at sexual maturity to obtain a high number and mass of eggs, must consider high body weight till 8-wk of age, after that restrict the body weight till sexual