Genetic analyses of generation means for a cross between two local breeds of chickens: Ш-inheritance of egg quality in F3 and backcross generations

摘要

External and internal egg quality traits are the primary selection objectives of breeders to maximize the return of saleable eggs. In order to help for developing an effective improvement program for egg quality traits, performances of F3?and backcrosses generations, derived from crossing Gimmizah with Bandarah developed strains, were used to estimate the components of genetic variability of egg quality traits in this experiment. The current results revealed that the differences between genetic groups were highly significant for all traits studied. Also the variations between F3?and backcrosses were highly significant differences for egg weight, shell weight, yolk weight, albumin weight and yolk index, while shell thickness, egg shape index and Haugh unit were not differ significantly in the same trend. Moreover, the results revealed that most of egg quality characteristics had negative estimates of additive??2A and dominance σ2d genetic variations. This may be due to the parental strains were closely related, what caused presence of many deleterious recessive genes, were expressed largely and resulted a very little genetic variations in egg quality traits. The degree of dominance (?) was varied from no dominance in shell weight to complete dominance of the low parent in yolk index and from complete dominance of the high parent in albumin weight and egg weight to over dominance of the low parent in Haugh unit. Contrarily, over dominance of the high parent was found in shell thickness, egg shape index and yolk weight, respectively.