Egg physical characteristics and hatchability

The physical characteristics of the egg play an important role in the processes of embryo development and successful hatching. The most influential egg parameters are: weight, shell thickness and porosity, shape index, described as maximum breadth to length ratio, and the consistency of the contents. The average values of the physical characteristics mostly meet the requirements for the embryo's development. For those eggs, whose parameters do not fall in to the average range, the incubation process is more successful if the shell is thicker than average, the eggs are more pointed rather than round, and the contents firm. The results reported for investigations into incubating eggs, whose weights are not within the average values, are contradictory. Both thick shells and firm interiors, which are accepted as being higher than average, lead to an increase in egg weight, which probably results in the more successful hatching of embryos from heavier eggs.