Genetic Analyses of Egg Quality in Khorasan Razavi Native Fowl Using the Bayesian Method

This study was conducted to estimate the genetic parameters influencing egg quality in Khorasan Razavi native fowl. (Co)Variance components were estimated by the Bayesian statistical method via Gibbs sampling in GIBBS3F90 software. 1000 eggs (28-29 weeks old) were collected from 775 hens of the ninth generation of Khorasan-Razavi Province native fowl breeding center. External (egg weight, specific gravity, long length, short length, shape index, shell strength, shell weight, shell thickness) and internal (yolk diameter, yolk height, yolk weight, yolk index, albumen diameter, albumen height, albumen weight, albumen index, Haugh unit) egg quality traits were measured. Six univariate animal models were used for estimation of genetic parameters and the best model for each trait was determined by deviance information criterion (DIC). Genetic and phenotypic correlations between traits were estimated using bivariate animal model. Direct heritability estimates ranged from 0.10 (egg width) to 0.39 (yolk index). For all traits except albumen diameter and albumen index, the inclusion of maternal effects in the model resulted in considerable reduction in direct heritability. Genetic correlations of egg weight with shell strength and shell thickness were negative. In conclusion, due to genetic correlations among external and internal egg quality traits, selection based on egg weight and shell thickness may improve external and internal egg quality traits. Also, including maternal effects in the form of genetic or permanent environment in the statistical model resulted in more accurate estimates for most traits.