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Calcium, a Key Factor for Egg Shell Quality Logo Feedia

Egg shell quality is a major concern for farmers in the poultry sector. Any crack in an egg’s shell is enough to downgrade an egg. Shell solidity is therefore a crucial factor for producing marketable eggs as a finished product. What precautions can be taken to avoid too many crushed or cracked eggs in a flock? How do you 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. However, egg shells are usually surprisingly sturdy: a shell that is less than 0.3 mm thick can withstand more than 3 kg! This strength is the result of the egg structure and resistance created from the combined properties of its compounds: phosphorus and especially calcium of which  90% of the eggshell is composed. The shell is formed in the hen's 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 will sustain this formation process by drawing upon their own bone reserves from the medullary bones.

What factors can influence the quality of the egg shell?

The older the hen, the weaker the eggshell. Commonly, egg size increases as hens age, their egg shells 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 continuous use of this calcium throughout the day thereby sparing their medullary bone reserves.
Good flock organisation as well as judicious scheduling of feeding times and lighting programs, can also contribute to the solidity of the eggshell.

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What are the consequences of a fragile egg shell?

Excessively drawing upon hens' medullary bone reserves results in weakening both the hens and the eggs. Besides a fragile shell, using bone calcium reserves produces a weaker egg shell can lead 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 fertilized will not lead to a healthy chick at hatch.
At the consumer level, cracked or microscopic cracks on eggshells can allow entry of foodborne infections into the egg such as salmonella. These can be a looming threat to consumer safety.

A gradual intake of calcium for a solid shell

The goal of producing a solid eggshell throughout the entire flock should be prepared far ahead of the laying period. The proportion of calcium in diets should be gradually increased over time, following a very strict schedule. During lay, part of the calcium intake should be provided in the form of coarse particles. Therefore, the calcium supply 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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Feedia embodies Techna's range of advice and solutions in breeding techniques and precision nutrition, serving the performance of production organisations, feed manufacturers and their breeder customers.