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ABSTRACT: Indigenous animal genetic resources should be preserved because of their well adaptation to the environment, their tolerance to low food availability and their sociocultural importance. The characterization of the quality of the products generated by heritage breeds may bring more arguments to encourage the raising of these animals. This study aimed at evaluating the egg performance and quality of Spanish indigenous Black Castellana (BC) breed as compared with a selected strain (Lohmann LSL-Classic). Four groups of 30 hens were arranged: 1) Lohmann hens fed a control diet; 2) BC hens fed the control diet; 3) Lohmann hens fed a diet including linseed at 70 g/kg (omega-3 diet); 4) BC hens fed the omega-3 diet. Egg production was higher by 12.3% for Lohmann hens but, since BC eggs were heavier by 15.4%, no effect of genetics was found on daily egg mass. Feed intake was higher by 5.0% for BC hens. Nonetheless, no difference was detected for feed conversion ratio. Eggshell was thicker by 6.78% in Lohmann eggs. Haugh units did not differ among freshly laid and stored eggs in Lohmann hens, whereas Haugh units decreased in stored BC eggs (80.5 vs. 76.7 vs. 72.3 at 0, 14, and 30 d of storage). Yolks of BC eggs contained less fat (57.5 vs. 60.8% DM), more protein (32.8 vs. 31.9% DM) and more cholecalciferol (1.25 vs. 1.22 μg/g DM), and showed lower proportion of saturated fatty acids (29.0 vs. 37.0%) and higher proportions of monounsaturated (45.7 vs. 39.6%) and polyunsaturated (25.2 vs. 23.4%) fatty acids. Feeding the omega-3 diet reduced the yolk proportions of saturated (32.5 vs. 33.5%) and monounsaturated (42.0 vs. 43.3%) fatty acids and increased those of polyunsaturated (25.4 vs. 23.2%) and ω-3 (7.05 vs. 2.42%) fatty acids. No effect due to genetics or diet was found on yolk color score or on yolk content in cholesterol, cobalamin, retinol and γ-tocopherol. This study represents the first exhaustive characterization of eggs from Spanish indigenous Black Castellana breed.