Establishment of optimum regression models and determination of relationships between body measurements and slaughter traits in Japanese quails by path analysis

Path analysis was used to investigate direct, indirect and total effects of some morphological measurements on slaughter and carcass traits in Japanese quails. Bodyweight, shank length, shank diameter, breast circumference and body length measurements were taken from 219 Japanese quails. Bivariate correlations between carcass weight and morphological traits in quails ranged from 0.405 to 0.864. The direct effect of bodyweight on carcass weight was the strongest in the study and (path coefficient of 0.85) positively influenced carcass weight (P < 0.01). The direct effect of other linear-type traits on carcass weight was non-significant as revealed by t-test (P > 0.05). These traits were indirectly realised mostly by shank diameter. Thus, they were dropped from the final regression equations to obtain much more simplified prediction models. The optimum multiple regression equation for Japanese quails included bodyweight, with coefficient of determination (R-2) of 0.7463. The correlation between characters was determined in more detail by using path analysis in this study. Thus, it was shown that path analysis could be used for selecting a variable. The forecast indices obtained in this study could aid in weight estimation, selection and breeding programs