Poultry Husbandry Report

Heritability of egg size is approximately 60%-a very high value compared to the heritability of most other economic characters-and indicates that individual selection for egg size is to be preferred to family selection. A further simplification of the problem of changing the egg size of a flock by breeding selection is possible as a result of a study of genetic correlations between the weights of eggs laid at different times of the year. It was found that the weighing of several consecutively laid eggs in the first November of a spring-hatched pullet’s life provides a sufficiently accurate measure of a bird’s genotype for spring maximum egg weight. Thus it becomes possible to modify egg size by selection very rapidly since individual pulletrather than hen family-selection is effective for this purpose.