The objective of the research study was to assess the internal and external quality of eggs from the hens included in the national conservation programme in Poland; the quality of their eggs was assessed in reference to the hen age. The research study covered eggs from hens representing 8 lines (G-99, H-22, Z11, Ż-33, S-66, R-11, K-22, and A-33). 30 eggs of every hen line were collected on the same day; the age of the laying hens was 33 and 53 weeks. All the hens were kept on a litter floor and the stocking density was 6 birds/m2 ; the hens were on ad libitum feeding consisting of a standard diet for laying hens. The research study showed that the genetic distinctiveness of native breed hens was retained provided they were maintained in closed small populations to prevent outcross blood and where no selection was carried out to improve the productive traits. Furthermore, their genetic distinctiveness was manifested, among other things, through significant differences in the physical characteristics of eggs. The hens of the 8 lines studied and included in the conservation programme in Poland lay eggs with varying shell colours: white (G-99 and H-22), creamy (Z-11 and Ż-33), brown (S-66 and R-11), and dark brown (K-22 and A-33). The eggs from G-99 and H-22 hens were characterized by the highest total and yolk weights; however, their albumen values and Haugh units were slightly lower. When on feeding typical for laying hens, in the 33rd week, the hens of all the breeds/lines laid eggs with the yolks that showed a good colour (rated 6 – 7.76 points on the Roche scale); in the 53rd week this estimation value of egg yolk colour increased by 1 point on average. As hens aged, the weights of eggs and yolks increased as did the intensity of yolk colour but the quality of albumen and egg shells decreased.
egg quality, laying hens, age, biodiversity