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Animal Health

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Livestock Production
Thursday, February 28, 2008 12:43:43 PM
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Maintaining egg shell quality
Dr. Lokesh Gupta



Poor egg shell quality is a hidden cost to the egg producer. About 10 percent of eggs produced in hen houses are estimated to be uncollectible or break before intended use. An initial 2-5 percent may be lost as the shells may be cracked or broken to the extent that they are not suitable for collection. Another 3-8 percent is lost during collection, processing, packing and transportation to retailers. At Rs1.50 (US$0.04) per egg, a 5 percent loss could be as much as Rs 2.7 million (US$68,044) per year for 100 thousand layer house.


Shell quality


For commercial layer and breeding operations, shell quality means shell thickness and the strength to withstand trauma to reduce cracked eggs, and an increased number of saleable eggs.


Egg shell quality can be measured by seven factors:

    • Egg size and visual shell defects
    • Specific gravity
    • Shell colour
    • Shell breaking strength
    • Percentage shell (shell weight x100 / egg weight)
    • Shell thickness
    • Ultrastructure of the shell

Shell quality defects


There are several types of egg shell defects, some of which may be obvious while others may require careful observation to notice. Defects can be influenced by a layer's age, and whether it's suffered any form of disturbance before laying the egg. Shell defects include,

    • Misshaped eggs
    • Coated shells
    • Rough shelled eggs
    • Soft and weak shelled eggs
    • Cracked eggs
    • Dirty and glazed shells
    • Body checks

Factors influencing shell quality


Numerous factors affect the functional quality of the egg shell mostly prior to the egg is laid. The shell's thickness, for example, is determined by the amount of time it spends in the shell gland (uterus).


Diseases like infectious bronchitis (IB), Newcastle disease (ND), bird flu, and egg drop syndrome (EDS) affect the toughness and colour of the shell.


Large eggs are more prone to cracks; therefore the egg size must be well managed through nutritional and lighting management.


Shell thickness usually declines as the hen ages. Genes can also influence eggs, but a producer should not take it for granted as good genes can lose its balance and be upset by environmental stresses, which can damage or even kill the cells that form the egg shell. 


How to improve shell quality


Diet is an important part that determines egg shell quality, with half the battle already won if a producer is feeding his/her hens with the correct diet formulation. Vitamin C, sodium bicarbonate, aluminosilicates, minerals and calcium are all important ingredients poultry feed should have, especially for the layers. Each of the mentioned nutrients should also be at an appropriate level too.


Farming management, is also important to shell quality.


For more of the article, please click here


Article made possible through the contribution of AviTech.

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