The quality of fresh (1 d) and stored (7-14-21 d, 21 °C) eggs was studied in Italian dual-purpose breeds (Ermellinata di Rovigo (ER), Robusta maculata (RM)) and hybrids (Hy-Line Brown (HB), Hy-Line White36 (HW)), reared outdoors (4 m2/bird) and fed commercial feed. The eggs were analyzed at 4 ages, throughout different seasonal environmental conditions, from summer (31, 35 weeks; 25 °C) until autumn (39, 43 weeks, 15 °C). Each genotype showed significant (p < 0.01) changes in egg quality. In 1 d eggs, the eggshell thickness changed in RM and HW (quadratic), decreased linearly in ER; Haugh Units (HU) changed (ER-cubic) and decreased (hybrids-linear). In 7 d and 14 d eggs, HU linearly (p < 0.01) decreased, except in RM. In 21 d eggs, HU (ER linear decrease; HB, HW quadratic) changed. Significant negative correlations between albumen pH and height were seen in ER (at 1 d, 14 d, 21 d) and HW (at each storage time) eggs, and in RM and HB only in 1 d eggs. RM showed a quite stable albumen quality and a lower total egg mass than ER which showed a more variable albumen quality, due also to a lower eggshell thickness and shape index. The hybrids produced a higher total egg mass than the purebreds and showed an intermediate variation of the egg quality, with an albumen quality higher than those of ER and RM only in 1 d egg, as a result of a higher albumen weight.
Keywords: albumen quality; dual-purpose; egg; hens; storage.