Question about feeding eggshells to chickens?

[DaveOmak]

All the recycled egg shells are roasted at 275 F. to kill any pathogens that may be present... don't want to continually re infect the birds...

 

[RonP]

I keep a small can in the bottom of my stove.

I place all used shells there.

When I next use my stove, the shells dry and "cook".

No extra energy wasted.

 

[aart]

I just rinse them well under running water to any albumen off then let them air dry, crush them and mix with oyster shell all goes in a separate container always topped off.

 

[CrazyTalk]

There is a whole lot of Ca in grass (and vegetable scraps), and at least free range chickens have produced good shells long before the commercialization of oyster shells.

Before the commercialization of oyster shells, chickens were laying 30-50 eggs a year. They're now bred to lay 300+. Their calcium needs are drastically higher.


Nothing done with chickens 100 years ago is relevant today - they're not the same birds.

 

[Chris09]

There is a whole lot of Ca in grass (and vegetable scraps), and at least free range chickens have produced good shells long before the commercialization of oyster shells.

Grass as in the typical backyard grass has very little nutritional value and the Calcium (Ca) is quite low.
Now you might want to also keep in mind that chickens are not herbivores and do a poor job extracting some nutrients from tough fibrous plants.

Commercial oyster shells have been around for a very long time. The use as a Calcium supplement in poultry is mostly by the backyard raiser. Commercial feed Mfg. use Calcium Carbonate (CaCO3) which is mined from the earth.

 

[Chris09]

If I understand correctly, both eggshells and oyster shells are the same form of calcium, which is calcium carbonate (CaCO3).

So there should not be significant difference in absorption.

Yes and No.

Not all Calcium Carbonate (CaCO3) are the same, you have to take in consideration the particle size of the Calcium Carbonate. Small particle size does not absorbed as well as a larger particle size making for a less dense weak eggshell.

* Eggshells - Small particle size and poor absorption making for poor eggshell quality .
* Fine Limestone - Small to Medium particle size making for a little better quality eggshell.
* Oyster Shells - Medium particle size and have a better absorption than eggshells and fine limestone.
* Large Limestone - Large particle size, good for eggshells density because of the large Calcium particle size.

Calcium Carbonate used for livestock/poultry is a mixture of both medium and large particle size and is very good for eggshell quality.

 

[ChickenCanoe]

The larger pieces of oyster shell acts as a soluble grit in the gizzard, staying there longer, slowly dissolving, as opposed to being passed quickly.

Semantics. There's no such thing as soluble grit. Grit is insoluble for the very reason that it doesn't dissolve in the digestive tract and stays in the gizzard to aid in grinding feedstuffs. That must be in the form of granite, flint or some other insoluble stone.

Oyster shell serves a totally different purpose. Large particle oyster shell does stay in the upper digestive tract longer so it comes in contact with calcium absorption sites in the small intestine at night when the egg is normally in the shell gland.
Useful as grit it is not, because by the time it reaches the gizzard, the acidity of the digestive tract turns it into mush.

...

1) Is it okay to feed just their eggshells, or do I also need to add oyster shell to the mix?

2) On that note, will they every need an oyster shell supplement? I guess I was wondering if eventually the "cycle" of calcium would get weak and they would need calcium from an outside source. These eggshells will have lots of calcium since they've been eating oyster shell, but if they only eat eggshells, will each egg have less calcium in it since it's being cycled through the chicken? Does that make sense?

I may be off base and over-worrying, but I figured I'd find out for sure instead of doing something totally wrong and stupid.

Thanks.

It's ok to feed. I just make sure they can't make the connection from feed eggshells to their own eggs.

It's calcium so can still aid in overall Ca intake but as small particle, isn't necessarily any more beneficial as the small particle type in layer feed.

http://www.nutrecocanada.com/docs/s...-formation-and-eggshell-quality-in-layers.pdf

A lot depends on what you are feeding them to start with. Are they getting "layer feed"? or something else? Layer feed has a generous amount of calcium, and is designed to be a complete feed. If they get that, in theory, they don't need oyster or egg shells. Though, it's not a bad idea to provide either item free choice. If they are not getting layer feed as their primary feed (making up at least 90% of their diet) they will definitely need the calcium supplement. Over the full egg laying cycle, you may find that your chooks egg shells are not as strong as they were when they first started laying. That's why chickens naturally take a break from egg laying, to build their calcium reserves. By providing calcium on the side, no matter what the source, you're allowing your girls to self regulate.

X2
If they're all laying, a layer feed should make up most of their feed but a supplement on the side isn't a bad idea for those hens that feel the need.

If I understand correctly, both eggshells and oyster shells are the same form of calcium, which is calcium carbonate (CaCO3).

So there should not be significant difference in absorption.

But since the chickens will also require calcium for their bones and other bodily functions, their calcium will be steadily depleted if their only calcium is their own recycled shells.

The layer feed should certainly have calcium in it, as gardener said.

In any case, it isn't a going to quickly turn into a crisis that you can't find the oyster shells...so clean and crush your eggshells and use them as you suggested. If you notice their new eggs have thinning shells, then you will know that you need to provide supplemental calcium.

Good points, but if they're getting calcium, the source doesn't really matter unless it's dolomitic limestone which contains too much magnesium.
Ca is Ca and won't deplete if recycled by the hen.

There are studies (a search here should find them quickly) that have shown that the reason oyster shell works so well is it stays in the upper digestive tract (where the most calcium absorption sites exist) longer than other calcium supplements.

I agree, your shells aren't going to turn thin overnight. And I was not stating fact, simply my observations. I think it took about 2 weeks before I noticed the thin shells when I only fed back egg shells.

The calcium absorption sites are in the small intestine but you're right in that the large particle size gets there slower. That usually puts it there at night when the birds are sleeping and the egg is likely in the shell gland.

There is a whole lot of Ca in grass (and vegetable scraps), and at least free range chickens have produced good shells long before the commercialization of oyster shells.

Very little.
Someone on here once said that free range chickens get a significant amount of Ca from exoskeletons of bugs. That's not a significant source either.

All the recycled egg shells are roasted at 275 F. to kill any pathogens that may be present... don't want to continually re infect the birds...

I don't worry about the pathogens. Your eggs shouldn't have any of significance to begin with. If I do give shells, I make sure they don't resemble eggs. I usually just compost them for the garden.

I keep a small can in the bottom of my stove.

I place all used shells there.

When I next use my stove, the shells dry and "cook".

No extra energy wasted.

That's a good strategy.

Before the commercialization of oyster shells, chickens were laying 30-50 eggs a year. They're now bred to lay 300+. Their calcium needs are drastically higher.


Nothing done with chickens 100 years ago is relevant today - they're not the same birds.

X2
Good point. These aren't your grandpa's chickens.

Grass as in the typical backyard grass has very little nutritional value and the Calcium (Ca) is quite low.
Now you might want to also keep in mind that chickens are not herbivores and do a poor job extracting some nutrients from tough fibrous plants.

Commercial oyster shells have been around for a very long time. The use as a Calcium supplement in poultry is mostly by the backyard raiser. Commercial feed Mfg. use Calcium Carbonate (CaCO3) which is mined from the earth.

Good points as well.
I'm a bit concerned from an ecological point of view because oyster shell also needs to be recycled into oceanic oyster beds so oysters can build shell.

 

[RonP]

Semantics. There's no such thing as soluble grit. Grit is insoluble for the very reason that it doesn't dissolve in the digestive tract and stays in the gizzard to aid in grinding feedstuffs. That must be in the form of granite, flint or some other insoluble stone.

I'm not sure where you got your info, but this site seems to agree with my statement.

http://poultrykeeper.com/general-chickens/types-of-poultry-grit

As does this packaging.

 

[Chris09]

It depends on who you talk too, were there located and what they raise.
There are two types of grit, one being the common granite grit which is a insoluble grit the other being oyster shells sometimes called oyster grit or soluble grit.

Most breeders of poultry and pigeons outside the U.S. and some breeder of game fowl and pigeons inside the U.S. use the term insoluble and soluble grit and
I may have been the first to use both terms on this site.

Oyster shells is considered a insoluble grit because it does aid in some digestion and does not stay in the digestive system long so there is less of a chance of it clogging the digestive system like a insoluble grit could.

 

[Chris09]

If one look outside the typical poultry world and more into other forms of poultry there are a ton of types of grits and grit mixes.
Now the pigeon world has grit down to a fine science and more and more chicken breeders are using pigeon grit because it's so much better than the typical granite grit. Here is one grit mix that's for pigeons in the breeding season.

Redstone, Granite, Charcoal, Oyster Shells, Sea Shells, Anise Oil, Zinc Oxide, Manganese Oxide, Ferrous Carbonate, Copper Oxide, Iron Oxide, Calcium Iodate, Cobalt Carbonate etc.