estimation of the heterosis effect and comparison of growth curves for body weight trait in crosses between two selected lines in japanese quail

in the current study, two line with short-term divergent selection for high weight (hw) and low weight (lw) at 4 wk of age after 7 generation were analyzed in coturnix japonica quail. hw line was significantly higher than lw line at 28d of age (p<0.01). 21 females, and 11 male from the hw, 18 females plus 10 male from the lw lines were mated as reciprocal cross and within lines to produce hh, ll, hl, and lh groups. the mean of body weight in each group at first, second, third and forth wk of age and growth rate was compared to investigate the maternal and heterosis effects. there was significant differences between lines for these traits (p<0.01). however the effect of heterosis was not significant for all ages. moreover the reciprocal effect (maternal effect) was significant for all bw measured except for 4 wk bw in males and for 3 and 4 wk bw in females and for growth rate in first week of age in both males and females. the curve growth for all groups (hh, ll, hl, and lh) was compared with three models (gompertz, logistic, richard). the logistic model was fit and better than other models, on basis of coefficient of determination and error variance.