Impact of storage period on hatching egg quality, extra-embryonic structures, embryo morphometry, hatchability, and Rosa 1 chick quality

Storage duration affects the biological value of hatching eggs. The study evaluated the composition and characteristics of hatching eggs from Rosa 1 hens, the morphometric traits of embryos and chicks, and hatching results based on storage time. A total of 1 200 hatching eggs were divided into three groups: NS (control, non-stored), S4 (stored up to day 4), and S7 (stored up to day 7). Storage conditions were 17 °C and approx. 60% relative humidity. Each group's egg quality was measured for 30 eggs. Weight loss during storage was monitored. Lysozyme activity and viscosity were analysed from fresh eggs and incubated eggs on days 7 and 14, using thin and thick albumen or amniotic fluid. Embryo morphometry was measured on days 7, 10, 14, and 18, and posthatching results and the quality of 1-day-old chicks were assessed. Eggs stored for 7 days (S7) had higher (P < 0.05) weight loss compared to the NS group. The proportions of eggshell and yolk increased (P < 0.05) after storage, and the yolk index decreased. Vitelline membrane strength was lower (P < 0.001) in the S4 and S7 groups than in the NS group. The lowest (P < 0.05) pH levels of thin, thick albumen and yolk were observed in the NS group. Lysozyme activity increased (P < 0.001) in the thin albumen of eggs in the NS and S4 groups and the thick albumen from the NS group than in others. On day 7 of incubation, group S7 showed higher (P < 0.05) lysozyme activity in thick albumen, with no activity in amniotic fluid. By day 14, lysozyme activity increased (P < 0.001) in group S7's thick albumen and S4 and S7 groups' amniotic fluid. Viscosity was highest (P < 0.05) in fresh eggs' thin and thick albumen from group S7, but on day 7, thick albumen viscosity was lowest. On day 14, amniotic fluid viscosity was higher (P = 0.009) in group S4 than in NS. Seven-day-old embryos in group S7 had lower (P = 0.004) weight than others. Eye diameter in S7 embryos was also smaller on days 7 and 18. On day 10, NS group embryos had shorter body diagonal lengths. Storage up to 7 days adversely affected hatching efficiency. Storage affected the navel area of 1-day-old chicks, with the highest neck length in male chicks from group S4 and the lowest in females from group S4. It is concluded that egg storage at 17 °C and 60% relative humidity could be limited to 4 days to maintain hatchability and qualitative features.