The objective of the present study was to estimate heritabilities as well as genetic and phenotypic correlations for egg weight, specific gravity, shape index, shell ratio, egg shell strength, egg length, egg width and shell weight in Japanese quail eggs. External egg quality traits were measured on 5864 eggs of 934 female quails from a dam line selected for two generations. Within the Bayesian framework, using Gibbs Sampling algorithm, a multivariate animal model was applied to estimate heritabilities and genetic correlations for external egg quality traits. The heritability estimates for external egg quality traits were moderate to high and ranged from 0.29 to 0.81. The heritability estimates for egg and shell weight of 0.81 and 0.76 were fairly high. The genetic and phenotypic correlations between egg shell strength with specific gravity, shell ratio and shell weight ranging from 0.55 to 0.79 were relatively high. It can be concluded that it is possible to determine egg shell quality using the egg specific gravity values utilizing its high heritability and fairly high positive correlation with most of the egg shell quality traits. As a result, egg specific gravity may be the choice of selection criterion rather than other external egg traits for genetic improvement of egg shell quality in Japanese quails.

Decontamination of egg shells is required to improve the microbiological safety of the fresh hen eggs used for human consumption or for hatching. Conventional chemical decontamination methods involving quaternary ammonium disinfectant, sodium hydroxide, phenol, hydrogen peroxide or formaldehyde, leave residues on egg shells that may damage the cuticle layer. Therefore new techniques of egg shells decontamination, such as ultraviolet (UV) radiation, have been developed. This review aims to evaluate the data from available literature and to provide a general review of UV light treatment application for egg shell decontamination. Data shows that UV treatment was effective for the inactivation of the bacterial population present on clean egg shells and recently contaminated shells. Combined treatments such as UV light with ozone or hydrogen peroxide (H2O2) improved the inactivation of microorganisms. Recent advances in science and engineering indicate that treatment with UV light has a competitive advantage in comparison with traditional egg shell sanitation treatments for decontamination.