Changes in eggshell thickness, shell conductance and pore density during incubation in the Peking Duck (Anas platyrhynchos f. dom)

Abstrakti

Shell thickness, shell conductance (water-vapour conductance), and pore density are important properties of eggs that influence the success of embryonic development. We determined these properties in the blunt end, the equator and the sharp end of both unincubated and hatched eggs of Peking ducks. In unincubated eggs, we found that shell thickness increased from the blunt end to the sharp end, water-vapour conductance was the highest in the blunt region and lowest in the equatorial region. Analysis of hatched eggs showed that during incubation the equatorial and sharp end regions became thinner (due to calcium uptake by the embryo), resulting in nearly similar eggshell thickness in all regions after hatching. Pore density and shell conductance, however, increased during incubation both in the equator and blunt end. Our results suggest that the increase in shell conductance during incubation is in this species due to an increase in pore density and not due to thinning of the eggshell.