Eggshell mottling, does it affect incubation results?

Eggshell quality is a critical factor in poultry farming, influencing both hatchability and egg safety. While candling eggs is commonly used to detect the presence of an embryo, it also serves as a valuable tool for identifying shell abnormalities. One such abnormality, known as eggshell mottling, appears as small translucent spots on the shell. The degree of mottling varies, ranging from a few scattered spots to nearly complete coverage of the eggshell. Understanding its causes, effects on incubation, and management strategies can help poultry farmers improve egg quality and hatch rates.

A visual representation of eggshell mottling severity, ranging from Category 1 (highly mottled) to Category 4 (minimal mottling).

Eggshells are primarily composed of calcium carbonate crystals (calcite), which are arranged in columns. The spaces between these columns contain pores that allow for gas exchange. The structure and strength of these calcite columns rely on a protein matrix. When a hen experiences stress, disease, or nutritional deficiencies, it can disrupt the formation of this matrix, causing the columns to become disorganized. As a result, moisture accumulates in the gaps between the columns, creating translucent spots once the egg dries after laying.

Factors contributing to eggshell mottling include:

• Hen stress due to environmental changes, overcrowding, or transportation.

• Diseases affecting eggshell formation, such as infectious bronchitis.

• Nutritional imbalances, particularly deficiencies in calcium, phosphorus, or vitamin D.

• Aging flocks, as older hens may lay eggs with weaker shells.

A study conducted by Pas Reform examined the impact of eggshell mottling on incubation outcomes. Researchers tracked 1,313 fertile eggs from three different flocks of the same breed and age, recording parameters such as egg weight loss, shell mottling, and color. Hatch rates were also analyzed, and unhatched eggs underwent a break-out analysis to determine the cause.

Key findings from the study:

• Eggs with severe mottling exhibited greater weight loss during incubation.

• Heavily mottled eggs had lower hatchability rates compared to eggs with minimal mottling.

• Variation in individual egg weight loss was higher in eggs with extensive mottling, affecting incubation consistency.

These findings indicate that eggshell mottling negatively influences incubation success. Further research is needed to explore how different breeds and flock ages are affected.

To minimize the occurrence of eggshell mottling and improve hatchability rates, poultry farmers should consider the following best practices:

1. Regular Egg Quality Checks:
   
   
   • Include eggshell mottling assessments in routine quality checks.
   • Use a candling table or flashlight to evaluate eggshell transparency and identify mottled eggs.
2. Optimize Hen Health and Nutrition:
   
   
   • Provide a balanced diet rich in calcium, phosphorus, and vitamin D to support strong eggshell formation.
   • Monitor for diseases affecting eggshell integrity and implement biosecurity measures.
   • Reduce stress factors by maintaining stable housing conditions, proper ventilation, and optimal stocking densities.
3. Monitor Weight Loss in Mottled Eggs:
   
   
   • For batches with heavy mottling, track egg weight loss at day 18 of incubation.
   • Ensure weight loss remains within the optimal range to support successful hatching.

Eggshell mottling is a significant concern for poultry farmers, as it can affect both egg strength and hatchability. By incorporating eggshell mottling assessments into quality control protocols and addressing the underlying causes, farmers can enhance egg production and improve overall incubation success. Ongoing research and monitoring are essential to developing better strategies for managing this common yet often overlooked eggshell abnormality.