What's the difference between grit and oyster shell?

[IamRainey]

I give my chickens both. Plus crushed eggshells. But the grit and the oyster shell particles are about the same size. They appear to have the same density. I know the grit is essential to grind down the other food they eat but wouldn't the oyster shells do the same thing? Certainly the shell is not dissolving in their crops very fast...

And where does the grit go? I don't see it in their poo. Does it dissolve? Or do they grind it down to nothing? Does it provide its own nutritional minerals?

I do it. I just don't understand it.

 

[Edwiges]

I might be wrong but i think oyster shell is just that, grit has more minerals in it

 

[ChickenCanoe]

Grit and oyster shell are two completely different things.
Grit is insoluble sharp stones.
Oyster shell is soluble calcium carbonate.
Once OS hits the proventriculus (first stomach), the digestive juices make it mushy, thereby rendering it ineffective in the gizzard for grinding foodstuffs.
Grit on the other hand is made up of something like granite or flint. It takes a long time for it to dissolve but eventually, the acidic environment and constant grinding dissolve it.
I get annoyed when I hear people use the misnomer 'oyster shell grit', because they are two different things. That phrase causes people to think they are somehow related.
Grit needs to be sized appropriately for the age/size of the bird to be effective, in that it needs to lodge in the gizzard and not pass right through.

 

[IamRainey]

Thanks for that explanation.

As I said, I provide both but I'm happier understanding why.

 

[ChickenCanoe]

I thought I'd add that most birds need grit.
Oyster shell is only for extremely productive birds building enough shells that require more calcium than the 4% in layer feed or for those feeding something other than layer to laying hens.

 

[Ptera]

I've read that only birds who swallow their food/seeds whole (chickens, pigeons, etc.) need grit. Songbirds that remove the hulls from their seeds first (chickadees, sparrows, cardinals, canaries, etc.) don't require it.

 

[Ptera]

I've read that only birds who swallow their food/seeds whole (chickens, pigeons, etc.) need grit. Songbirds that remove the hulls from their seeds first (chickadees, sparrows, cardinals, canaries, etc.) don't require it.

They almost all need calcium, though.

 

[ChickenCanoe]

All birds need calcium but most don't need that much calcium.

 

[rosemarythyme]

And where does the grit go? I don't see it in their poo.

Actually it does show up in their poop every so often. You'll generally not notice it because by the time they pass it, it's been worn down to a fraction of the original size.

 

[ChickenCanoe]

X2
Usually when I butcher a rooster, there is a significant amount of grit in the gizzard contents.