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Calcium, a Key Factor for Egg Shell Quality

Egg shell quality is a major concern for farmers and the poultry sector. A mere crackle on its shell is enough to downgrade an egg. Solidity is therefore a crucial condition for marketing an egg as a finished product. What precautions can be taken to avoid too many crushed or cracked eggs in a flock? How to make eggshells stronger?

Downgraded eggs account for 3.5 to 12% of all produced eggs. This rate increases drastically between 60 and 70 weeks of laying period: it can reach up to 20% at the end of a laying cycle. Still, egg shells are usually surprisingly sturdy: a shell that is less 0.3 mm thick can withstand more than 3 kg! This resistance is the result of the egg structure and the power resulting from the combined properties of its compounds:  the phosphorus and especially the calcium (more than 90%). The shell is formed in hens' uterus by the precipitation of calcium carbonate on a membrane. To make the eggshell, hens mainly use their available dietary calcium. If this mineral is not available in sufficient supplies as the shell is forming, hens need to sustain this formation process by drawing upon their own bone reserves, the medullary bone.

What factors can influence the quality of the egg shell?

The older the hen, the weaker the eggshell. While egg size increases as hen age, their egg shell tend to thin out and become lighter over time. Dietary calcium intakes should be supplied in sufficient amounts so hens do not have to pull too much calcium out from their reserves. How can this result be achieved? Providing hens with coarse particles of calcium causes the ingested calcium to stay longer in their gizzard.  As a consequence hens are able make a continuous use of this calcium throughout the day thereby sparing their medullary bone reserves.

A reasoned flock organisation as well as judicious scheduling of feeding times and lighting programs, can also highly contribute to the solidity of the eggshell.

What are the consequences of a fragile egg shell?

Excessively drawing upon hens' medullary bone reserves results in weakening both hens and eggs.  Besides a fragile shell, a weaker egg shell can lead to to higher risks of bone fractures, osteoporosis. As a consequence, hens may also stop laying eggs and even die.
As far as breeder flocks are concerned, the main goal is to have your hens lay eggs whose shells are intact. Indeed, a fractured or broken egg that has already been fertilised will not lead to chick birth.
At the consumer level, crackled or microscopic crackles on eggshells can cause foodborne infections such as salmonellosis. These can be a looming threat to consumer safety.

A gradual intake of calcium for a solid shell

The goal of getting a solid eggshell should be prepared far ahead of the laying period. The proportion of calcium in diets should be gradually increased over time, following a very tight schedule. During lay, part of calcium intakes should be provided in the form of coarse particles. Therefore these calcium supplies will be available in due time as hens begin to form their eggshell.

To ensure a quality shell throughout the laying period, the TECHNA Group experts can provide you with customized ranges of nutritional solutions. They will be able to guide you on the methods and conditions allowing for optimal calcium intakes. For more information, please contact our experts!

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