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# The chicken eggshell quality

Joël Gautron

► To cite this version:

Joël Gautron. The chicken eggshell quality. Webinar on Egg quality, Feed channel - Adisseo, Apr 2018, Paris, France. hal-03625794

HAL Id: hal-03625794

https://hal.inrae.fr/hal-03625794

Submitted on 31 Mar 2022

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Distributed under a Creative Commons Attribution 4.0 International License
# The chicken eggshell quality

## Joël Gautron

INRA, « Défenses de l'œuf, valorisation, évolution »
Unité mixte de recherches Biologie des Oiseaux et Aviculture,
37380 Nouzilly, France

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Impact
(2013-2017)

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# The chicken eggshell formation

* ✓ Eggshell biomineralization in uterus (fast process)

* ✓ 5-6 g of mineral (calcium carbonate) are deposited within a 20 h period

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95 % of calcium carbonate (calcite) → Interaction → 3.5 % organic matrix (protéines, protéoglycanes)

* ✓ Control of the mineralisation process

## Ultrastructure, Mechanical properties
# Eggshell biomechnical properties measurement

## Acoustic egg tester :

A piano hammer comes to hit the rotating egg on 4 different places

The acoustic vibration is registered by a microphone

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RF: Resonant frequency (Hz).

dumping

Broken egg (1) / Intact egg (0).

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Dynamic stiffness

Kdyn (KN/m)

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# Eggshell biomechnical properties measurement

## Instron mechanical data:

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- (Sd) (stiffness en N/mm) : Shell deformation under a specific load

- (F) (Eggshell Breaking strength en N). A constant load is applied on egg equator until break

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## Biomechanical parameters calculated

- Shell percentage %

- Shell index (g/100cm²)

- Shell thickness (mm) : T= l/23.5

- Elastic modulus which describes the material impact on shell rigidity

- Eggshell fracture toughness (Kc) en N/mm³/²

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Improve the eggshell quality

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Shell quality Depends on Numerous factors

➤ Genetic

➤ Hen physiology (age, mold)

➤ Environment of hens (lighting programs, temperature)

➤ Nutrition and management of hens

➤ “Insult”: rearing system, egg transport...

➤ egg sorting...

→ Genetic, optimal nutrition limit but do not eliminate breakage

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# Extension of the Laying Period

The current genetic strategy is to improve persistency in lay and to extend the laying cycle of existing flocks (+ 40 days between 2000 and 2011; financial and environmental interest!)

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Weekly decreased in egg quality between 70 and 90 weeks of age estimated to be quite linear: - 0.4 haught unit, - 0,02% for egg shell, + 0,05 cm2 egg surface (European data, 2015, practical conditions)

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# Improve the eggshell quality

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Mass or fabric

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* Mass : nutrition, génétique, environnement, lighting programs

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* fabric : génétique (œggsHELL matrix proteins), nutrition (trace elements)

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# Improve the eggshell quality

## Nutrition (Nys et al)

### Effect of dietary calcium levels on eggshell (Hartel, 1990)

Diminution of calcium intake affect shell quality

<table><thead><tr><th rowspan="2"></th><th colspan="3">Dietary calcium (%)</th></tr><tr><th>&lt;2.5</th><th>3.5</th><th>&gt;4</th></tr></thead><tbody><tr><th>Shell thickness (µm)</th><td>348<sup>a</sup></td><td>374<sup>b</sup></td><td>378<sup>b</sup></td></tr></tbody></table>

### Effect of Mn-Zn supplementation on eggshell quality (Mabe et al. 2003)

Trace elements (Mn) do not affect the shell amount, but improve eggshell breaking strength

<table><thead><tr><th>Supplementation</th><th>Mn-Zn</th><th>Eggshell %</th><th>Breaking strength (N)</th></tr></thead><tbody><tr><td></td><td>0-0</td><td>9,7</td><td>29,5a</td></tr><tr><td></td><td>30-30</td><td>9,5</td><td>30,8ab</td></tr><tr><td></td><td>60-60</td><td>9,7</td><td>32,2b</td></tr></tbody></table>

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# Improve the eggshell quality

## Identification of genes and proteins affecting shell texture

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**444 Main candidate proteins to be involved in the shell biomineralization process**

## Predicted functional activities of the identified matrix proteins ?

(Marie et al., 2014, 2015a,b)

Classification in 3 different groups according to their potential functions

Associated to
mineralization process

Involved in the regulation
of activity of proteins

Antimicrobial and other
proteins

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Impact
(2013-2017)

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# Improve the eggshell quality

## Identification of genes and proteins affecting shell texture

Use as biological markers for genomic selection to reinforce eggshell breaking strength

* Associate transcripts with published and private SNPs, QTLs related to shell quality

*(Collaboration with breeders and avian genetic teams)*

Use for precise phenotyping of the shell mechanical properties

* ✓ Molecular variants → Structure/function

* ✓ Study of protein interactions with mineral

* ✓ Structural *in situ* studies. Synchrotron, XRD, XANES, FTIRM, HRSEM to provide new insights into mechanisms, which control eggshell texture and its mechanical properties

*(Collaboration with synchrotron SOLEIL and University of Granada (Spain))*

## Selection of laying hens haplotypes for the continued improvement of eggshell solidity

### How genes are evolving according to vit D metabolite nutritional status

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