Grit for chickens

What does everyone use for grit in the winter?
Do you buy that limestone rock or granite grit? Do you feed it with or without oyster shell?
I wonder how long the rocks they picked up in the summer and Fall last in their gizzards?
I recently ran out of grit, basically fine gravel I picked up beside the road for them and was wondering how long they are good without new grit?
Also what size of grit is the best for full grown layers? I feed about half layer pellets and half whole spring wheat so I know they need lots of grit to grind up those whole grains but how much?
Looking forward to hearing what everyone else offers their birds!

I've had my chickens go a month in winter without supplemental grit, and all my feed is homemade so pretty coarse stuff. I do give them a bucket of grit every so often, I think they get better feed conversion the more grit they have, but I could be making that up. Doesn't have to be granite, coarse sand works too. But oyster isn't strong enough to make really good grit I think on its own. And I don't give the ducks any oyster in winter when they aren't laying anyway, so I especially think they need some extra grit.

I provide mine with hard grit all winter as well as oyster shell. I just buy a bag of it at the store. I like the coursest stuff they carry for the mature birds, have you seen the size of the rocks they eat when free ranging?!
I just dump a pile of it in each pen every once in a while through the winter and let them pick and scratch through it.

Miry, I am glad that you brought this up. I don't have much information to give about grit, but have some comments. I would like some questions answered too. Yes. How long does grit stay in the body to grind up stuff. That is premium in my mind what I would like to know. A month, Country Thyme said with his, but yes, would the conversion to something more digestible be done sooner if given grit earlier.

When I buy grit I get it from Surecrop in the big bag that weighs so much I can barely pick it up. How can a bag so small weigh so much, smiling. Ya. It is what they call #2 grit, there is finer grit, but I don't bother with it. The floors in my coop are dirt and little rocks I think. Yes. I have seen the size of some of the rocks the chickens gobble up when outside and it has shocked me.

If you are buying grit for adults, I would suggest #2.

We see the ravens on the side of the roads in masses. Eating something. I am pretty sure that they are eating the road grit. There is so much sand and rock spread on our roads to keep them beautiful, that these birds have a hay day eating gravel from the sides of the road. What else would they be gobbling up.

Speaking of that. I need to get out there and spread some grit around, seem to forget about these things until it is brought up. The runs for my chickens are pretty devoid of snow, as we shovel, but the ground is frozen, and I can bet my bottom dollar that the grit that they would love to be eating is just a teaser, imbedded in the frozen ground . Yes, good reminder, gotta go and spread some grit!! Have a wonderful day, CynthiaM.

I feed the purchased grit #2 like CynthiaM for my adults, they have a large dish of it summer and winter. I also have a dish of the finer grit in with any young birds that I might be raising. As well I always have a huge bucket of oyster shells available to all my layers for the calcium.

XOX Monika

I also keep free access to granite grit (layer size for the adults) and calcium all the time. It is surprising how much they use, and when they do run out and I refill the little bin they seem interested and start to eat it right away. I couldn't get the regular oyster shell last time at the feed store but I got soluble calcium which is I guess the same idea.

I believe #1 grit is recommended for chicks #2 grit for adult chickens and #3 for turkeys. I use mostly #2 granite grit, have never tried limestone. I mix my grit and oystershell together (50:50 or a bit more oystershell) and have it available at all times in the coop winter and summer.

I like #3 for my full grown birds, but it is tough to find here.

Thanks for the replies guys!
I have never seen mine actually eating the gravel/ rocks outside so have no idea what size they pick up on their own.
I read one time that if the rocks are too big in their gizzzard they wont so have enough room for the food so will need to eat all the time or lose weight????
I put quite a mix of sizes in and see the bigger ones are still there so hopefully they know what size they need!
But then I wonder about the bantams, do they need a smaller sized rock?