Genetic Differences in Avian Egg Shell Formation

Evidence is presented that family, strain, breed, and species differences occur for eggshell quality. A variety of methods employed to determine the quality of eggshells have shown that genetic differences may be identified. Heritability estimates have been calculated and reported for several eggshell quality parameters. Published results of selection programs show success in demonstrating that population means for egg shell quality may be changed. Investigations of physiological parameters in genetically divergent lines have demonstrated where differences do and do not occur. Conclusions from the literature reviewed are presented.