Influence Of Eggshell Ultrastructural Organization On Hatchability And Candidate Genes Associated With Eggshell Quality Traits

Though many factors affect the hatchability, this article tries from the angle of eggshell ultrastructure to explore the factors influencing hatchability. Expelling the role of other factors, we study the influence of eggshell ultrastructure organization on hatchability and genes.Eggshell quality is associated with hatchability, and ultrastructural organization is an important eggshell quality parameter. To the determine relationship of shell ultrastructural properties with hatchability, we measured the effect of Rhode Island White eggshell thickness, mammillary layer thickness, effective thickness and the average size of mammillary cones on hatchability. Egg had the highest incidence of hatching when total eggshell thickness was324.5-364.5μm. Mammillary layers range in80.5-94.5μm had the highest hatchability. As such, hatchability correlated positively with both eggshell thickness (r=0.30; P<0.05) and mammillary layer thickness (r=0.28; P<0.05). In addition, the correlation between the average size of mammillary cones and hatchability was not statistically significant. However, a significant positive correlation was observed between the average size of mammillary cones and mammillary layer thickness. It can be concluded that eggshell thickness and mammillary layer thickness affect hatchability. Crystallite size and crystallite orientation have no effect on hatchability. All samples have same two crystallite orientation:{104} and{018}.With respect to eggshell ultrastructural properties, two Rhode Island White strains were used to to determine the relationship of shell ultrastructural properties with hatchability. The strain2had thick shell, mammillary layer and effective layer compared to strain1. Eggs of strain2had significantly higher shell strength than strain1. As such, shell strength was very highly correlated with both eggshell thickness (r=0.82; P<0001) and effective thickness (r=0.82; P<0001). In addition, a significant difference in hatchability among eggs from different breeder flocks was found. Comparing to strain1, strain2breed was associated with a low incidence of hatching, suggesting that these eggshell ultrastructural properties could affect hatchability.In the analysis, all eggshell ultrastructure organization traits hold low heritabilities. Furthermore, the genetic and phenotypic correlations of the same egg quality traits including, eggshell thickness, mammillary layer thickness, the average size of mammillary cones are positive.Twenty-three candidate SNPs from4genes were genotyped by a high throughput genotyping method, MALDI-TOF MS, to search for mutations related to eggshell ultrastructural properties.384pure-line Rhode Island White layers were selected for this study. As for the following4genes: Ovalbumin、Ovocleidin-116、Ovocalyxin-32and ChEST985k21. Associtations were found for: Ovalbujhhmin with eggshell thickness and effective layer thickness, Ovocleidin-116with mammillary layer thickness、effective layer thickness and the average size of mammillary cones, Ovocalyxin-32with eggshell thickness, ChEST985k21with eggshell thickness and mammillary layer thickness.