Post-hatching growth traits of 7226 chick of Dokki-4 (as a native breed) were genetically evaluated. Records of individual body weight (BW) at hatch and biweekly thereafter up to 16 weeks of age were collected in two generations. Data of daily gain (DG) between intervals of hatch-4, 4-8, 8-12 and 12-16 weeks were also used. Variance components and heritability estimates for these growth traits were estimated using DFREML procedure of single-trait (SAM) and multi-trait (MAM) animal models. Percentages of direct additive genetic variance (0-2, ). for BW traits estimated by the MAM appeared to be higher than those estimated by the SAM. The percentages of cr.!, for BW traits ranged from 6.0 to 19.9% when using the SAM and from 9.6 to 17.8% when using the MANI. The percentages of common environmental variance ( ) for BW traits obtained by the MAM were higher (averaged 22.0%) than those obtained by SAM (averaged 17.4%). Little differences were observed in estimation of crc.2, between the SAM and MAM for analysis DG traits. Generally, estimates of heritability based on direct additive single-trait ( hA2s ) and multi-trait ( hA244) animal models for all growth traits were low or relatively moderate. Estimates of heritability for BW traits resulting front MAM were somewhat larger (hM ranged from 0.10 to 0.18) than those obtained by SAM analysis ( hA2s ranged from 0.06 to 0.20). Most of the genetic correlations (r(;) among growth traits at different ages were high and averaged 0.52 among BW traits and 0.25 among DG traits. All estimates of common environmental correlation (rc)among BW traits and among DG traits were positive and with moderate or high magnitudes. |
