During the recent decades, the scientific community turned its attention towards the dual purpose lines and crosses that might offer a suitable solution for two problems in poultry breeding - the use of male chickens for meat and the use of female chickens for rearing in alternative types of systems for egg production. Hence, a study with four groups of birds: a dual purpose cross „Salmon“, a dual purpose purebred line „BB“, a laying line „L“ and a laying hybrid line „ISA-Brown“ was conducted. The aim was to compare the morphological traits, as well as the fertility and the hatchability of the eggs, obtained from „ISA-Brown“, compared to the dual purpose „Salmon“ reared at IAS-Kostinbrod, and the local dual purpose and laying lines involved in its creation. As a result of the conducted research, we can conclude that the selection for high performance, larger eggs and the presence of heterosis in hybrids has to some extent a positive influence on most of the morphological traits determining the quality of the eggs produced. In addition, negative consequences for their hatchability, embryo survival and some morphological parameters such as increased width of the egg and increased diameter of the yolk were also observed. On the other hand, in the stock hybrids, compared to the purebred lines and the dual purpose crosses, this can also be considered as a sign of deterioration of the nutritional quality of the eggs.
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