Grit is just bits of rock they use to grind up their food in the gizzard. The stuff you buy is granite which works really well because it is so hard and it is cheap. They just screen the waste from a granite quarry to get the right size, package that, and sell it. But chickens can use any rock as grit. Softer rock just doesn’t last as long. Grit eventually gets ground up in their gizzard and eventually passes on through their system as fine sand. Decent sized chunks of granite might last a month but softer rock will not last as long.
Chickens will get grit from the soil if they have access to the ground. If your flock forages much on the ground they will find their own. Probably doesn’t help you much with small chicks.
There are a lot of ways you can get grit for young chicks besides buying something labeled as grit.
You can buy a coarse sand like construction sand. Don’t use the real fine sugar sand like play sand. That stuff is so fine it will go right through their system.
You can go to a gravel driveway or gravel road and get some of the smaller stuff. For young chicks, use pretty small pieces. For adults, they can use anything the size of a pea or smaller. If your roads are salted, you might want to rinse this first. Too much salt is bad for them too.
You can just use sand, maybe from a sand bar in a river or stream or a beach. If it is a salt-water beach you might want to rinse it, again to get rid of the salt.
Take some dirt from your property and give them some. I purposely take dirt from my run where the older flock has pooped. This will introduce anything that lives in the ground or that the older flock has to them while they are young and in the brooder. They’ll be exposed to this later anyway. I’d prefer that exposure come while they are in the brooder and I can better observe them and better control their environment.
To me, this does three things. It gets grit in their system. It gets any probiotics the older flock has into their system. And it exposes them to any bad things, like Coccidiosis, the older birds have. For some things like Coccidiosis they can develop immunities better when they are very young and, as I said, they are eventually going to be exposed anyway. Coccidiosis can usually be controlled by keeping the brooder pretty dry. I think they will be healthier if they are not raised in a sterile environment and are later dumped into a non-sterile environment.
People do all sorts of things concerning grit. If all they eat is commercial chick or chicken feed, they don’t even need grit. Commercial feed has already been ground up, even crumbles and pellets. I personally like to get their system set up for it, but a lot of people never give them grit in the brooder and do fine as long as they don’t feed them treats like green stuff or grains, just the commercial chick feed.
