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Tips about the factors that affect eggshell quality

With this article, Zucami’s technical team intends to present TIPS that will help our customers to understand the different factors that affect egg shell quality.

The egg industry is constantly changing due to technological changes, growing market demand and pressure from consumers and regulatory agencies.

For consumers, shell quality is of vital importance, being also a crucial factor for egg food safety, as any alterations in the cuticle or damaged shell make the eggs more susceptible to bacterial contamination.

The quantity of eggs with damaged shells represents approximately 6-8% of the total egg production.

These eggs cannot be marketed, leading to substantial economic losses for the egg production industry (Hamilton et al., 1979).

Poor eggshell quality also poses a significant risk to egg food safety, as eggs with damaged shells are more prone to bacterial contamination.

The percentage of damaged eggs can increase up to 20-30% of the production in hens towards the end of the laying period (65-70 weeks of age).

This is one of the main reasons to limit the production cycle to 70 weeks of age or one year of laying (Travel et al., 2011; Bain et al., 2016).

The gradual decrease in eggshell quality (breakage resistance) with hen age is partly due to the fact that the amount of deposited minerals remains almost constant during the production cycle (approximately 6 g), while the egg size slightly increases with hen age (from 60 to 67 g).

Eggshell formation is the fastest known biomineralization process.

The eggshell is mainly composed of a calcium matrix over an organic framework. It also contains minerals such as magnesium, zinc, manganese, iron, among others, but in very low proportions.

Eggshell Pigmentation

It depends on the genetics of the bird and is given in brown-colored eggs due to the concentration of pigments called porphyrins, which are deposited in the calcium matrix and the shell cuticle.

As hens age, the brown color of the eggshell deteriorates.

Most of the eggshell pigment (protoporphyrin) is deposited in the outer calcareous layers of the eggshell, with a smaller amount being deposited in the cuticle (Roberts and Scott, 2016).

A healthy liver and intestines, along with the absence of respiratory diseases, will ensure better shell pigmentation in brown layers.

Quality issues with the eggshell often result from a combination of factors. These include:

The strain and genetic selection

Some strains have been selected to produce thicker and stronger eggshells. Moreover, in modern strains where longevity and productivity are the primary objectives, selection for shell quality becomes paramount.

The age of the hen

The thickness of the eggshell decreases as the hen ages – the weight of the egg increases while the weight of the shell remains the same, resulting in thinner shells.

Molting

The benefits depend on the type and severity of the molt performed, as well as the age of the hens. This is a common practice in some countries to improve the quality and thickness of the eggshell that has deteriorated due to age. However, in some countries, this practice is prohibited.

Stress

Stress generated by situations such as high stocking density, heat, and/or extreme temperatures.

Heat stress, due to its impact on feed intake and the electrolyte imbalance caused by excessive loss of bicarbonate ions through panting and hyperventilation.

Some diseases

Newcastle disease, Infectious Bronchitis, Low Pathogenic Avian Influenza, Mycoplasma gallisepticum, Mycoplasma synoviae, and Avian Pneumovirus.

Lighting Program

The first initiating factor for egg formation is light, which acts on the hypothalamus to activate the secretion of FSH and LH, responsible for egg formation and production.

The lighting program directly affects egg production and size, thus directly impacting the quality of the eggshell.

It is important for laying hens to have a rest or dark period of no less than 8 hours, so a lighting program that does not stress the birds should not exceed 16 hours of light per day.

Pullet rearing or rearing of the layer

During the rearing stages, the future laying hen is formed. It is crucial for the pullets to achieve intake not only of feed but also of accumulated nutrients in each stage. Therefore, it is important to use the appropriate feed particle size for each stage, as well as the correct formulation based on the strain’s requirements.

Intestinal Health

This is one of the most important factors for the health and nutrition of birds, as a healthy intestine will result in excellent nutrient absorption and significantly improve immunity.

Nutrition

Proper nutrition of the hen throughout the laying period with optimal levels of calcium and trace elements (Mn, Zn, Cu) is a key element in maintaining overall hen health, accumulating sufficient calcium in the medullary bone, and forming and maintaining the tissues of the oviduct during extended laying cycles while maintaining good shell quality (Nys 2017).

Eggshell quality is a crucial factor for egg food safety.

Maintaining egg production and, specifically, eggshell quality through extended production cycles (up to 100 weeks) is a significant challenge for the industry, achievable through genetic selection of hens. However, proper nutrition of the hen during the laying period is a key element in maintaining overall hen health and unlocking its genetic potential.

Tips about the factors that affect eggshell quality

With this article, Zucami’s technical team intends to present TIPS that will help our customers to understand the different factors that affect egg shell quality.

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