Egg shell benefits from calcium source

Using the feed material calcium pidolate in layer feed reduces the number of downgraded eggs and is proven to improve bone strength, research from the French National Centre of Veterinary and Animal Studies (CNEVA) has revealed.

Registered as PIDOLin PCa, calcium pidolate is derived partly from limestone, which contains supplementary amounts of the amino acids argenine and proline – both key components of collagen, which makes up 95% of the eggshell’s membrane.

How it works

While other sources of calcium are absorbed between 10-30%, depending on the pH of the gut, the calcium from PIDOLin PCa is absorbed in the gut at a constant 95%, because it isn’t pH dependent.

“Pidolic acid is a precursor of amino acids in intestinal cells. These amino acids (argenine and proline) are fundamental in the binding process of calcium. Argenine accounts for 28% of calcium binding protein. More presence of that binder results in better absorption and transfer of calcium in the blood and the uterus where the egg shell is produced,” said Xavier Roulleau, manager of Terafeed, the French company which developed the calcium pidolate molecule.

Although a balanced nutritious diet will provide the bird with calcium, as the bird gets older the hen is unable to mobilise enough for shell development and to fully replenish the calcium it has mobilised from the bone. This means it is left with a calcium deficit.

“Producing an egg drains calcium reserves from the bone, so later in the laying cycle shell quality gets poorer. By using PIDOLin PCa, the bird is able to put more calcium into reserve,” he told Poultry World on a fact-finding trip to France.


The feed material could also aid broiler production, as it is proven to strengthen bones and accelerate growth.

“The more calcium animals have in the blood, the less they lose from the bone. By using PIDOLin PCa when the birds are young, you can stimulate skeletal development and limit osteoporosis as the birds get older,” Mr Roulleau said.


Tests revealed that when the product was used on pullets for the first 12 days, they obtained better weights and a 10% increase in bone density at 21 days old.

Bigger bones result in a larger bone marrow and therefore the birds are able to mobilise more calcium for development and egg production.


Studies from CNEVA revealed that using PIDOLin PCa later on in the production cycle could reduce the amount of downgraded eggs by 30% within 10 weeks.

“Eggshell isn’t just a layer of calcite. It’s a complicated structure,” explained Greg Dunn, managing director of importing agent Agrosom UK.

“Shell strength is related to the density of the piers (or nucleation sites) attaching shell to membrane. When the bird is young, these are closely packed and the calcite bridges are strong. But when the bird gets older, the membrane quality suffers, the nucleation sites are more sparse, eggshell colour becomes noticeably whiter, and microcracks and losses increase.”

While most would think the smaller the egg the weaker it becomes, in fact larger eggs are more fragile.

“Every egg has got 2g of shell weight, whether it’s large or small. Therefore as the egg size gets bigger, it becomes more vulnerable to breakages,” explained Mr Colin Gravatt of Humphrey Feeds.

“Every time the egg weight goes up by one gram, the bird has to eat between 2.25-2.50 more grams of food, so it’s a lot of food for no more money, especially if those eggs are getting broken.”

CASE STUDY: Pampr’oeuf packing and production centre, Pamproux, Western France

Paul Agblo, manager at Pampr’oeuf, has been using PIDOLin PCa in his birds’ rations for eight years. He uses the product in the chicks’ feed for the first eight days to enhance early bone development. Trial results showed that birds which had received the product as part of their diet were notably taller than control groups.

“I noticed the drinkers in the shed of birds that were being fed with PIDOLin PCa were 2cm higher than the control group at the same age,” explained Mr Agblo, adding that the treated birds weighed the same as the smaller control group.

Mr Agblo gives the pullets one week’s treatment immediately before forcing them into lay at 18 weeks and then, depending on breed, automatically restarts treatment between 45 and 55 weeks. Results showed that downgraded eggs were reduced by 30-40%.

“I also noticed an improvement in egg colour,” Mr Agblo said.

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