Growth Curves Fitting in Japanese Quail Di-Allele Crosses and Comparison of Growth Patterns of Crossbreds

The main part of growth performance in birds is as a result of gene combination effects, which their changes require an optimal mating system in order to use general and specific gene combination ability. The purpose of the present study was to evaluate the growth patterns of four strains combination Japanese quail in a partial di-allele cross. For this purpose, four strains of Italian Speckled (A), Tuxedo (B), Pharaoh (C), A&M Texas (D) were used in a partial di-allele cross design to produce different gene combinations during four generations. Four functions including Gomperts, Richards, Logistic and Weibull were fitted for body weights records of different combinations. The best function for each combination was selected by goodness of fit criteria’s. Then, function parameters and growth patterns of the best function were compared between combinations. The results of goodness of fit criteria’s showed that the Gompertz function was the best one for binary combinations of AB, BA, CD, DC and reciprocal combination of ABCD-DCBA, DCBA-ABCD, while Weibul function was found to be the best function for quadrille combinations of ABCD, DCBA for describing growth curve. The effects of year and month of hatching on all growth patterns were significant (P<0.05). Also, the combination effect on initial weight, final weight, age and weight at inflection point and, one-day weight was significant (P<0.05). The effect of sex on curve growth parameters was not significant (P>0.05) except for 45-days weight. The DC combination had the highest initial and final weight, age and weight at inflection point compared to other combinations. The quadrille combinations, especially DCBA had the highest final weight, 45-days weight and, 45-days growth rate, but the lowest puberty index. Also, age and weight at inflection point in DCBA combination were at moderate level among combinations and showed better performance compared to other crosses indicating of the most heterosis in this combination.