genetic properties of productive traits in iranian native fowl: genetic relationship between performance and egg quality traits

the present study was conducted to estimate correlations among performance and egg quality traits in iranian native fowl. data were collected from 21,679 birdsat the isfahan native fowl breeding center to derive genetic parameters for performance traits and egg quality traits were measured on eggs of 1,020 birds. genetic correlations of performance and egg quality traits were estimated with a bivariate animal model using asreml software. body weight at hatch, 8, and 12 weeks of age (bw0, bw8 and bw12, respectively) positively (0.05 to 0.82) correlated with egg weight (ew), shell weight (sw), specific gravity (sg), yolk height (yh) and albumen weight (aw). bw0 and bw12 negatively (-0.10 to -0.26) correlated with shell strength (ss) and shell thickness (st). genetic correlations of bw8 and bw12 with albumen height (ah) and haugh unit (hu) were highly negative (-0.45 to -0.55), whereas bw12 showed positive correlation with shape index (si) (0.22). shell weight showed high positive genetic correlation with age at sexual maturity (asm) (0.75), while its genetic correlation with egg number (en) was highly negative (-0.71). en also showed high negative correlation with yolk and albumen weight (-0.91 and -0.75, respectively). based on the present results, selection for higher bw will lead to production of eggs with higher internal quality. in contrast, this kind of selection will reduce the shell strength and shell thickness. therefore, selection should be based on an index including performance and egg quality traits. this will help to develop indigenous strain of meat-cum-egg type chicken.