Storage time and eggshell colour of pheasant eggs vs. the number of blastodermal cells and hatchability results

The aim of this study was to investigate the number of the embryo blastodermal cells and hatchability of pheasant from eggs of different eggshell colours depending on the length of the storage period before hatching. On the day of collection, dark-brown and olive eggs were characterised by a similar and significantly higher (by about 48%) number of embryo BCs in comparison with light-brown and blue eggs. Dark-brown eggs stored longer than one day had the highest, while blue-shelled eggs the lowest, number of BCs. The number of BCs found in eggs with blue and light-brown coloured eggshells stored for 10 days was similar and significantly lower (by 27.7%) in comparison with dark-brown eggs. With the lengthening of the storage period, the number of blastodermal cells in eggs of all eggshell colours declined as a result of necrobiosis. In comparison with the dark-brown and olive-shelled eggs, eggs with blue eggshells had higher (by about 7.0%) weight loss during the 21 days until hatching. The dark-brown and olive eggs were found to have a 10.3% higher proportion of eggs considered as fertilised in comparison with the blue-shelled eggs. Eggs with dark-brown shells stored for 2-4 days prior to hatching, in comparison with blue-shelled eggs, had a higher proportion of fertilised eggs. The dark-brown and olive eggs stored for 7 and more days before hatching possessed a higher value of this trait in comparison with the eggs of light-brown and blue eggshells (x = 80.9 against 66.4%). The highest drop in the share of fertilised eggs, which amounted on average to 3.25% for each day of storage, was observed in the blue-shelled eggs. The dark-brown eggs stored for 7 days before being placed in an incubator had higher hatchability from fertilised eggs (by 17.8%) in comparison with the eggs with blue eggshells. In the case of eggs stored for 8 to 10 days, values for this trait were higher for the dark-brown and olive-coloured eggs than for the blue-shelled eggs. The highest mean decrease of chick hatchability from fertilised eggs was observed in the case of the blue-shelled eggs (7.93% for each day). The dark-brown eggs had significantly higher (by about 22.0%) chick hatchability from fertilised eggs than the blue-shelled eggs. Moreover, the dark-brown and olive eggs, in comparison with the blue-shelled eggs, were characterised by a significantly higher hatchability after each period of storage before incubation. The highest negative trend-cycle was observed for eggs with blue shells, while the smallest--for olive-shelled eggs. Directly after laying, pheasant eggs differed with regard to the developmental advancement of the blastodermal embryo depending on eggshell colour. Longer storage time caused the numbers of blastodermal cells in eggs to decrease. The group with blue shells had a lower proportion of fertilised eggs and lower hatching results than the dark-brown eggshell group. It was also demonstrated that the value of hatchability indices decreased significantly irrespective of eggshell colour after seven days of storage prior to hatching.