# Societal impact of biomineralization in chicken eggshells

Joël Gautron

► To cite this version:

Joël Gautron. Societal impact of biomineralization in chicken eggshells. Summer school of biominer-alization, ECTS, Jul 2021, Valbone, France. hal-03663456

HAL Id: hal-03663456

https://hal.inrae.fr/hal-03663456

Submitted on 10 May 2022

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# Societal impact of biomineralization in chicken eggshells

Joël GAUTRON

Joel.gautron@inrae.fr

Directeur de recherche
Research Director

UMR BOA

(33) 2 47 42 75 40

université
de TOURS

UMRBOA

<figure><img src="image_4.png" /></figure>

Biologie des Oiseaux
& Aviculture
The chicken eggshell formation

✓ Eggshell biomineralization in uterus (fast process)

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

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /></figure>
# Eggshell biomineralization

<figure><img src="image_7.png" /><figcaption>First events of nucléation</figcaption></figure>

<figure><img src="image_8.png" /></figure>

**Time 1 (5-6 h Post ovulation):**
ACC particles nucleate on the whole eggshell membranes. Form massive deposits

<figure><img src="image_9.png" /><figcaption>Calcite formation</figcaption></figure>

<figure><img src="image_10.png" /></figure>

**Time 2 (6-7 h post ovulation):**
Interface-coupled dissolution precipitation process
Direct transformation of ACC into calcite aggregates on mammillary knobs

<figure><img src="image_11.png" /><figcaption>Larger calcite crystal units deposition</figcaption></figure>

<figure><img src="image_12.png" /></figure>

**Time 3 (>7h post ovulation):**
Additional cristallisation events on calcite template
Avian eggshell biomineralization

<figure><img src="image_13.png" /></figure>

Cuticle

<figure><img src="image_14.png" /></figure>

Surface

Time 5 (11 to Oviposition):

- Formation of palisade layer. Generation of a compact layer with crystals all oriented perpendicular to the surface

- Deposition of a thin layer of vertical structure

- Cuticle deposition

- Oviposition, drying and cracking of cuticle

<figure><img src="image_15.png" /></figure>
# Socio-economic context

## Eggs

An autonomous close chamber to allow the embryo development

<figure><img src="image_16.png" /></figure>

Must contains the entire components necessary for embryo

<figure><img src="image_17.png" /></figure>

* Well-balanced nutritious ingredients

* Lot of compound (> 1000) with a broad range of biological activities

* Protective systems (natural defenses)

Physical defense (Mainly shell)

Chemical defense (Proteins with antimicrobial activities)

<figure><img src="image_18.png" /></figure>

## Table eggs

A basic ingredient for human food
# Socio-economic context

## Table eggs

A basic ingredient for human food

<figure><img src="image_19.png" /></figure>

* 68.2 MT of egg produced each year in the word > 1200 billions eggs each year

* 14,7 billions eggs in France each year

* The cheapest animal food of high nutritional quality

* No religious prohibition

<figure><img src="image_20.png" /></figure>
# Eggshell in the socio-economic context of the egg

Eggshell is the only non-consumable part of an egg.....

## Mineral eggshell

- Ensure the physical protection

- Avoid bacterial penetration

- Ensure a thermic protection

- Allow gaz exchanges

- Calcium source for embryo

<figure><img src="image_21.png" /></figure>

... but its quality is crucial for the marketing of the egg

<figure><img src="image_22.png" /></figure>

INRAO
# Socio-economic context

## Economic issues

**Downgraded eggs due to deteriorated egg quality**

poor internal qualities leading to white/yellow separation problems

Dirty, cracked or broken shells

**Hatchability of the chick**

Shell allows gas exchanges during embryo development

## Health issues

**Risks of toxi-infections for the consumer (Salmonellosis)**

Eggshell as a physical barrier

**SHELL QUALITY**

Shell mechanical properties

## Ethical issues

**Housing systems and societal demand**

Consumer demand for non cage and free-range systems

→ Lower shell quality

Long life cycle (shell quality decreases with age of birds)

<figure><img src="image_23.png" /></figure>
# Avian eggshell biomineralization and shell mechanical properties

<figure><img src="image_24.png" /></figure>

95 % of calcium carbonate (calcite) ← Interaction → 3.5 % organic matrix (proteins, proteoglycans)

## Role of organic matrix proteins at pivotal events

* ✓Stabilization of amorphous calcium carbonate (ACC)

* ✓Polymorphs, morphology and size of crystals

## Ultrastructure, Mechanical properties
Maintain and improve shell quality

<figure><img src="image_25.png" /></figure>

Mass or fabric ?

<figure><img src="image_26.png" /></figure>

Mass: nutrition, génétique, environnement, lighting programs

<figure><img src="image_27.png" /></figure>

fabric : Regulation of shell matrix proteins and genetic selection
# Eggshell biomineralization

<figure><img src="image_28.png" /></figure>

## Predicted functional activities of the identified matrix proteins ?

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

<figure><img src="image_29.png" /></figure>

<figure><img src="image_30.png" /></figure>

Impact
(2013-2017)

INRAE
# And now ? How to improve shell quality ?

## Physiology

Understand the mechanisms of shell
manufacturing and determine the origin of
its weaknesses

<figure><img src="image_31.png" /></figure>

<figure><img src="image_32.png" /></figure>

## Genetics

Classical and genomic selection

## Recent Developments and Future Prospects :

* ✓ Genomic selection to taking into account scientific advances in the knowledge of mechanisms

* • Candidate gene approach

<figure><img src="image_33.png" /></figure>

Défenses
de l'œuf
DOVE
Valorisation Evolution

<figure><img src="image_34.png" /></figure>

PEGASE

Au cœur de la recherche
et de la formation
en production animale

Candidate Genes of eggshell calcification in laying hens
(CACAO)

Eggshell Calcification Polymorphism Candidates (POLCACAO)
# Using recent advances in genetics and genomics to improve eggshell strength

<figure><img src="image_35.png" /></figure>

<figure><img src="image_36.png" /></figure>

Impact
(2013-2017)

<figure><img src="image_37.png" /></figure>

INRAO
# Using recent advances in genetics and genomics to improve eggshell strength

## Marker-assisted genomic selection

<figure><img src="image_38.png" /></figure>

Single nucleotide polymorphisms (SNP) (ex: G/C)

Single nucleotide polymorphisms (SNP) (ex: G/C)

<figure><img src="image_39.png" /></figure>

Changes in amino acid sequence

Modification of the function of protein

© 2013 Encyclopædia Britannica, Inc.

## Polymorphism usable in genetic selection

<figure><img src="image_40.png" /></figure>
# Using recent advances in genetics and genomics to improve eggshell strength

## Marker-assisted genomic selection

<figure><img src="image_41.png" /></figure>

Single nucleotide polymorphisms (SNP) (ex: G/C)

Single nucleotide polymorphisms (SNP) (ex: G/C)

<figure><img src="image_42.png" /></figure>

Insertion of stop codon
deleterious mutation

New protein

© 2013 Encyclopædia Britannica, Inc.

## Polymorphism usable in genetic selection

<figure><img src="image_43.png" /></figure>
# Using recent advances in genetics and genomics to improve eggshell strength

## Marker-assisted genomic selection

### GENOTYPING

- Blood collection from laying hens

- Analysis of SNPs (Genotyping chips)

### PHENOTYPING

- Collection of eggs laid by layers

- Measurement of biomechanical properties

- Number of broken eggs

- Eggshell breaking strength

- Eggshell thickness

- Eggshell elastic modulus

- Eggshell toughness

### STATISTICS

#### Association test

**Statistical test to identify the presence of SNPs related to greater shell mechanical properties**
Conclusions- Take home messages

* Biomineralization mechanisms in birds' eggs determine the mechanical properties of the shell

* The societal and socio-economic challenges of this mineralization process are important

* Economic, health and ethical issues

* Using the information on eggshell biomineralisation, genetic improvement can be achieved

* This component involves many actors in the egg sector:

* ✓ Egg producers

* ✓ Genetic selection companies

* ✓ Nutritionists and formulators

* ✓ Decision-makers (political, economic, food industry, supermarket sales)

<figure><img src="image_44.png" /></figure>