Diversity of the Cuticle Layer of Avian Eggshells

Abstract

The structure and mineral composition of eggshell cuticles were studied in species of birds. The approximate thickness of the cuticle layer at the top of shell columns was about m in the Red Junglefowl ( ), about m in the White Pelican ( ), about m in the Japanese quail ( ), about m in the Greater Flamingo ( ) and about m in the Humboldt Penguin ( ). The matrix of the cuticle layer decalcified with EDTA was composed of vesicles in a variety of sizes in all birds. Major elements in cuticle materials detected by X-ray microanalysis were O, C, Ca and P, and their percentage numbers of atoms decreased in this order. The concentration of P was significantly higher in the cuticles of the quail, flamingo, and penguin than in those of the junglefowl and pelican. Ca mapping on electron-microscopic images showed strong signals in the shell layer and weaker ones in the cuticle layer, whereas P mapping showed that signals were mostly confined in the cuticle layer. X-ray di raction analyses on the inside of the shell layer showed a profile of calcite crystals of calcium carbonates in all birds. In the cuticle materials, the profile was of calcite in the junglefowl, and a mixture of calcite and vaterite in the pelican. The profiles in cuticle materials of the quail, flamingo and penguin showed no specific signals, indicating that mineral compounds are amorphous in these forms. It was suggested that the diversity of mineral structures in the cuticle layer is caused by the presence of phosphorous, in addition to the structure of the cuticle matrix.

Eggshell characteristics and cuticle deposition in three laying hen genotypes housed in enriched cages and on litter

“…A higher cuticle coverage (P ≤ 0.001) was in eggs produced by Lohmann Brown compared to Isa Brown and Hy-Line Silver Brown. However, housing system did not significantly affect the cuticle coverage in Kusuda et al (2011) who concluded that the diversity in the structure of the cuticle layer may be linked to the environment of the nest, mainly humidity, which is hard to control in outdoor systems. Further investigation on the effect of genotype and housing management on cuticle deposition is needed because so-far available data are limited.…”

“…Eggshell cuticle is a very thin organic layer covering the eggshell surface and plugs the shell pores openings to limit water, gases, and bacterial penetration through the eggshell (De Reu et al 2006). It is composed of inner doi: 10.17221/75/2017-CJAS calcified and outer non-calcified water insoluble layers which are deposited directly onto the vertical crystal layer of the eggshell (Kusuda et al 2011). The structure of the eggshell is often expressed by eggshell quality characteristics including eggshell strength and thickness.…”

Eggshell structure, measurements, and quality-affecting factors in laying hens: a review

“…It is composed of inner calcified and outer non-calcified water insoluble layers which are deposited directly onto the vertical crystal layer of the eggshell (Rose and Hincke 2009;Kusuda et al 2011). Unfor-doi: 10.17221/46/2015-CJAS tunately not all avian eggs have a cuticle layer, and the distribution of cuticle is often patchy (Bain et al 2009;.…”

Enhancing the egg's natural defence against bacterial penetration by increasing cuticle deposition

“…Normally, the cuticle is likely to be under strong natural selection in birds such as pelicans or flamingos that live in damp and presumably more microbiologically challenging environments and that have much thicker cuticles than do chickens or quail (Kusuda et al . ). In modern egg production, to a large extent, the use of artificial incubation will have lessened the selection pressure for this trait.…”