Eggshell Quality Genetics in Japanese Quail: Heritability and Breeding Research Review
Quick Look
Researchers evaluated the genetics of eggshell quality in 934 Japanese quail hens.
More than 5,800 eggs were measured for shell quality and egg characteristics.
Heritability estimates ranged from 0.29 to 0.81, indicating moderate to high genetic influence on all measured traits.
Egg weight (0.81) and shell weight (0.76) showed particularly high heritability.
Egg specific gravity was strongly correlated with shell quality traits.
Egg specific gravity may be an effective selection tool for improving shell quality.
The findings demonstrate that shell quality can be improved through selective breeding.
Why This Research Matters
Eggshell quality directly affects hatchability, egg breakage, shipping success, and food safety. While nutrition and management influence shell quality, breeders often ask whether stronger shells can be genetically selected.
This study examined the heritability of several external egg-quality traits in Japanese quail and estimated the genetic relationships among them. Understanding which traits are highly heritable helps breeders determine where selection is likely to produce long-term genetic improvement rather than temporary environmental changes.
Study Summary
Objective
To estimate the heritability and genetic relationships among external egg-quality traits in Japanese quail.
Study Design
Researchers evaluated 5,864 eggs collected from 934 female Japanese quail belonging to a dam line that had undergone two generations of selection. A Bayesian multivariate animal model using Gibbs sampling was used to estimate both heritability and genetic correlations among the measured traits.
Traits Evaluated
Egg weight
Specific gravity
Shape index
Shell ratio
Eggshell strength
Egg length
Egg width
Shell weight
Major Findings
All measured traits showed moderate to high heritability.
Estimated heritabilities ranged from 0.29 to 0.81, indicating that genetics contributes substantially to differences among birds.
The highest heritability estimates included:
Egg weight: 0.81
Shell weight: 0.76
These values indicate that selection for these traits is likely to produce consistent genetic improvement over generations.
The researchers also found strong positive genetic and phenotypic correlations between eggshell strength and:
Specific gravity
Shell ratio
Shell weight
Correlation coefficients ranged from 0.55 to 0.79.
Based on these findings, the authors concluded that egg specific gravity could serve as a practical selection criterion for improving shell quality because it is both highly heritable and strongly associated with several important shell traits.
Practical Takeaways for Breeders
This study demonstrates that shell quality is not simply the result of nutrition or management. Genetics plays a substantial role, and several shell-related traits respond well to selection.
One particularly useful finding is that egg specific gravity is closely associated with shell strength and shell quality. Because measuring specific gravity is relatively simple, it may provide breeders with a practical way to identify birds carrying favorable shell-quality genetics.
The study also reinforces an important breeding principle: selecting for one highly heritable trait can improve future generations more effectively than selecting for traits with low heritability.
Limitations of the Study
The research evaluated a single selected dam line of Japanese quail. Heritability estimates may differ in unrelated breeding populations or commercial lines.
Only external egg-quality traits were examined. Internal egg characteristics, fertility, hatchability, and chick performance were not included.
The study estimated genetic relationships rather than identifying the specific genes responsible for shell quality. Molecular studies are still needed to locate the underlying genetic variants.
Finally, although heritability was high for several traits, environmental management—including nutrition, disease status, and housing—continues to influence eggshell quality and should not be overlooked.
Original Research
Narinc D, Aygun A, Karaman E, Aksoy T.
Egg shell quality in Japanese quail: characteristics, heritabilities and genetic and phenotypic relationships.
Animal. 2015;9(7):1091–1096.
DOI: 10.1017/S1751731115000506
Original publication:
How to cite this review: Poultry Nerds. (2026). Egg Size Genetics in Japanese Quail: Understanding QTL and Egg Quality Research (Research Review). Retrieved July 13, 2026, from https://www.poultrynerdspodcast.com/research-library/egg-size-genetics-japaneese-quail
Limitations
This article summarizes a peer-reviewed scientific publication and explains its practical application for poultry keepers and breeders. It is an original review written by Poultry Nerds and is not a reproduction of the original manuscript. Readers are encouraged to review the complete publication using the original publisher link provided above.