Building a good shell
Many egg producers currently produce around 360 eggs per hen housed. Genetic companies are currently breeding for more and more eggs per hen. The production cycles will be prolonged extremely, and this means that the critical period for 2nd grade eggs and broken eggs will be much longer.
Building the shell
Building a good shell is like building a good house with solid fundaments. These fundaments correspond with the albumen and the surrounding membranes. The better the albumen and membrane quality, the better the calcification process. It is the time available during the calcification process which determines the thickness of the palisade layer and therefor the major part of the thickness of the shell. However, like while constructing a house, it would not be solid if no defined structure and no cement would be used. The same is true for the eggshell. The organic matrix links all the crystals to each other making it a solid structure.
Albumen quality is mainly defined and expressed in Haugh Units. This parameter is based on the height of the thick albumen surrounding the yolk in relation to the egg weight. The higher this value, the better the quality. This albumen quality is a good indicator for the freshness of an egg and for the health of a flock. Albumen quality commonly declines with age of the bird. High quality albumen results in a direct improvement of the calcification process. This results in less broken eggs.
Egg shell quality decreases with age
Many factors have been found to affect eggshell quality, such as disease, nutritional status of the flock, heat stress and age. The decline in eggshell quality when the laying hens are getting older may in part be attributed to reduced intestinal calcium uptake as well as to increased egg size. The shell of a hen's egg consists up to 90-95% of calcium carbonate which is embedded in a protein matrix which determines the strength of the egg. Today’s commercial laying hens lay an egg almost daily and therefore require about 4-5 grams of calcium per day. The eggshell is made essentially from lime, which is made available either from the daily feed supplied or from the bones, especially the medullary bone marrow. The rate at which calcium is removed from the...
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