Grit

[ChickenCanoe]

My chicken have utility sand in their coop an run, will this be the same as grit?? Also, can I give them ground up egg shells in place of oyster shell?

Sand isn't likely to be of sufficient particle size to help.

Both egg shells and oyster shell are calcium carbonate. You can use egg shells but it is the large particle size of oyster shell keeping it in the digestive tract longer that provides its primary benefit.


For the OP, at 8 weeks your birds are ready for adult grit.
#1 size (chick grit) is about 1/16" and only helpful for the first 3 weeks.
#2 size is about 3/16" and for up to 7 or 8 weeks of age.
#3 (adult grit) is about 5/16".
There is a #4 grit at 3/8" is for turkeys over 8 weeks.

Even if only feeding chicken feed, offering the appropriate size grit helps develop the gizzard and thereby improves the chickens' digestive tract's ability to uptake nutrients from feed.

 

[ChickenCanoe]

Sand or any grit that isn't large enough to lodge in the gizzard will have minimal benefit aiding digestion.
It is when sharp insoluble stones remain in the gizzard till the acidic environment and constant grinding eventually wear them down and are passed where the benefit comes from.
I usually keep a cage cup of grit side by side with a cup of oyster shell for confined adults. For free ranging birds, I put a pile on the ground just outside the coop door or by a feeder.
I sprinkle a little chick grit on chicks feed the first few days and then I give them one of those quart size chick feeders full of grit.
It does wonders. I've seen firsthand that chicks of the same age, breed, line and parentage, some raised with grit, some without. When butchered, the grit fed birds' gizzards were twice the size of the others.

 

[GC-Raptor]

My local TSC only carries Chick Grit and Poultry Grit.
I only fed my Chicks Start & Grow feed for 8 weeks.
They stayed in my house till 5 weeks.
I then put them in the coop and offered them Chick Grit in a separate container.
Around 7-8 weeks I mixed Poultry Grit in with the Chick Grit about 50-50, till I used up the 5# bag of Chick Grit.
If they are eating whole grains, mealworms, bugs, grass, weeds. They need Grit.

CG

 

[chickengeorgeto]

... I’m confused about how/when to include grit in [chicks] diet.

There should never be any confusion about when to include grit in a chicks diet.
First the word "DIET" is inappropriate because we are not talking about a food item here but rather a necessary extension of a chicks body. A body extension BTW that serves as chicken teeth. Now if your chickens were taking a bottle or else gumming strained peas to death like a toddler does then insoluble grit might not be necessary but necessary and preferred are two different sides of the same coin. Of all the things that you can buy to go into your chickens faces, insoluble grit is perhaps the least expensive but it will provide the greatest benefits.