A selection experiment was conducted at the Poultry Research Center, Faculty of Agriculture, Fayoum University using a total number of 4923 birds of three successive hatches as a base population producing 655 females (333 for the selected line and 322 for the random bred control line) through four successive generations. The main results are summarized as follows:
1. There were significant differences due to generation effect for all BW's tested and all egg production-related traits studied, except at BW35 and AGE30. All BW's from 7 up to 35 days of age and all egg production-related traits -except BW1- were significantly affected by line favouring the selected line compared to the control line.
2. In the control line, average phenotypic response per generation for ASM and AGE10 showed fluctuations over generations, estimated by regression of phenotypic means on generation numbers were significantly positive for ASM and AGE10 (2.17 and 2.18 days). Significant positive changes for BW's at seven, 14, 21, 28 and 35 days of age being 0.79, 4.55, 6.84, 7.58 and 4.36g, respectively and AGE30 (1.96 days) however, negative significant changes were shown for EM10, EM30 and EM60(-3.10, -9.69 and -15.96g) .
3. In the selected line, the average phenotypic response per generation of multi-trait selection index estimated by the regression of generation means on generation number in ASM, BWSM, DN10 and AGE10 were significantly negative being -0.86 day, -3.30g, -0.25 day and -0.99 day, respectively, but was positive for BW 14 (+1.97g ).
4. Negative correlated significant changes were shown for all egg production-related studied traits (EM30, EM60, DN30, DN60, AGE30 and AGE60 being -3.98,-8.55,-1.41,-3.26,-2.06 and -4.07, respectively), except EM10 (1.75g, P≤0.01). The average genetic response per generation in ASM, BWSM, DN10 and AGE10 were -3.74days, -3.06g, -0.22day and -4.12 days, respectively.