Egg Morphometry and Eggshell Quality in Ring-Necked Pheasants Kept in Cages / Budowa jaja i jakość skorupy u bażantów obrożnych utrzymywanych w klatkach

The aim of the study was to evaluate the morphometry and shell quality of eggs laid by pheasants kept in cages, and also to analyse the dependence between egg shell colour parameters, its quality and morphometric characteristics. Four groups of 15 eggs (60 eggs), each classified according to their eggshell colours, i.e. blue, light brown, dark brown and olive, were examined. The eggs did not differ significantly between each other in their mean weight and olive-coloured eggs had a higher shape index (about 8.91 percentage points) than blue eggs. Blue and light brown coloured eggs had thinner shells than the dark brown eggs (by 33.57 and 27.97 μm, respectively). Blue eggs had the lightest shells (L* = 67.97) and the highest proportion of green colour in their shells since the a* parameter value for blue eggs was negative. A significant positive correlation was observed between the egg shape and the shell colour saturation (C*) and the proportion of yellow colour (b*) in it. In addition, a negative correlation was found between lightness in eggshell colour, its thickness and the egg shape (r = from -0.338* to -0.480**). In comparison with the data obtained from the literature concerning the quality of eggs laid by pheasants kept in aviaries and eggs laid by birds kept in cages, the eggs were described as having similar weights and morphometries along with greater shell thicknesses. Furthermore, our study confirmed that pheasant eggs with blue and light brown colour have poorer shell quality, a fact which has been shown already in earlier research. However, this fact is related to the lightness of the shell pigment rather than its colour.