The age and cross related dynamics of eggshell quality in three "DOMINANT CZ" crosses of layer chicken
Since eggshell plays the crucial roles in embryogenesis as natural barrier protecting the embryo, provider of the gas exchange and calcium for embryonic development the objective information on eggshell quality in different breeds and crosses of poultry is necessary for the adjustment and optimization of the respective incubation regimes. Different parameters of eggshell quality at 24, 32, 40, and 44 weeks of age were studied in three «DOMINANT CZ» crosses of layer chicken housed in cage batteries in similar conditions of nutrition and management. The effects of cross were the most significant for eggshell surface area, degree of mottling, and specific porosity. Eggshells of D-109 cross had higher surface area, darker color, higher degree of mottling, and lower specific porosity in compare to crosses D-104 and D-107. The maximal age related changes in all crosses were found for eggshell surface area and specific porosity. D-107 and D-109 were the most influenced by the hens’ age: eggshell surface area increased while specific porosity decreased. It could be assumed that the most crucial problems with the gas exchange during the embryonic development would be found in eggs of D-109, especially since 40 weeks of hens’ age.