Post-hatching growth traits of 7226 chick of Dokki-4 chickens were genetically evaluated. Data of individual body weight (BW) at hatch and biweekly thereafter up to 16 weeks of age were collected in two generations. Daily gains (DG) between intervals of hatch-4, 4-8, 8- 12 and 12-16 weeks were also studied. Variance components, heritabillties and breeding values for these growth traits were predicted using single-trait (SAM) and multi-trait (MAM) animal models. Percentages of direct additive genetic variance (rs2A ) for BW traits estimated by the MAM appeared to be higher than those estimated by the SAM. The percentages of common environmental variance (a2c) for BW traits obtained by the MAM were higher than those obtained by SAM. Generally, estimates of heritability resulting from MAM were (hAm) somewhat larger than those obtained by SAM analysis (h2As).The estimates of h2Am ranged from 0.10 to 0.18 for BW traits, while, they ranged from 0.06 to 0.20 for (h2AS)- The ranges in breeding values obtained by both models for birds with records (PBV) and their sires (SBV) and dams (DBV) without records for growth traits were generally moderate. For both models of evaluation, the ranges in estimates of SBV and DBV obtained for birds without records were moderate and lower than those recorded for birds with records. The direct additive responses of selection (SRA) predicted by both models were nearly similar in most cases. The additive selection responses recorded by the dams of birds were lower than those record-ed by the sires of birds without records. Across the whole period of growth, the ranges in SBV for sires without records estimated by MAM vs SAM averaged 73.9 vs 65.0 grams and 4.11 vs 4.01 grams for BW and DG traits, respectively, while the corresponding ranges in DBV for dams without records averaged 43.16 vs 31.6 grams and 1.75 vs 1.65 grams. The accuracy in predictors (i.e. PBV, SBV and DBV) obtained by III AM were nearly similar to those predictors obtained by SAM for most growth traits in Dokki-4 chickens. Correlations among ranks of genetic predictors (Le. PBV, SBV and DBV) estimated by SAM vs MAM for most growth traits were high and significant |
