Edited by Jennifer Bryant · Poultry breeder, Animal Science graduate, and Poultry Nerds Podcast co-host.
Chickens that eat grains or forage need grit, while laying hens may also need oyster shell as a calcium supplement. Grit helps chickens grind their food, and oyster shell helps laying hens make strong eggshells.
New chicken keepers mix these two up all the time. They both come in a bag, they both look like little rocks, and they sit on the same feed-store shelf. But they are not the same thing.
Grit: Chicken Teeth
Chickens don't have teeth. Instead, they have a strong, muscly pouch called a gizzard. Chickens swallow tiny stones, and the gizzard uses them to grind up food.
Grit is simply small, hard stones sized for chickens. It stays in the gizzard and does the chewing.
Who needs it? Any chicken that eats more than store-bought feed. That includes birds that eat grass, weeds, scratch grains, bugs, or kitchen scraps.
Chickens that eat only pellets or crumbles don't really need grit, because feed breaks down easily on its own. Free-range chickens often find little stones in the dirt. Still, a dish of grit is cheap and handy, especially for birds kept in a run or in winter when the ground is frozen.
Baby chicks need grit too if they eat anything besides chick starter. Look for "chick grit," which is smaller.
Oyster Shell: The Eggshell Builder
Oyster shell is crushed shells from the sea. It's mostly calcium. A hen uses a lot of calcium to build an eggshell almost every day.
Layer feed already has extra calcium. But some hens need a little more, especially busy layers. Thin or soft shells can be a sign a hen could use more calcium, but they can have other causes too.
Who needs it? Laying hens.
Who doesn't? Chicks, young birds, and roosters. Extra calcium isn't good for birds that aren't laying.
How to Offer Them
Put grit and oyster shell in two separate small dishes. Don't mix them into the feed. Hens are surprisingly good at eating what they need, when they need it.
If you have roosters or young birds in the flock, separate dishes let the laying hens help themselves while the others mostly ignore it.
Quick Cheat Sheet
Grit = teeth. For grinding food.
Oyster shell = calcium. For eggshells.
Each one gets its own dish.
Neither one replaces good chicken feed.
Starting a laying flock from scratch? Find breeders offering hatching eggs and chicks at Hatching Egg Directory.
