poultrykeeper logo

Poultry Grit

mixed poultry grit

In this article, you will learn about the purposes of the two different types of poultry grit and how you can feed these together as mixed poultry grit. I also have a suggestion for a chicken grit feeder and will leave you with some tips on making a chicken grit from crushed eggshells at home. 

There are two types of poultry grit: Insoluble grit, which is flint or granite, used in the gizzard to grind down food mechanically, and soluble grit, a calcium supplement to help laying-hens produce strong eggshells. Soluble grit is usually derived from limestone or crushed oyster or cockle shells.

Chickens will pick up anything that is grit-sized whilst foraging, so it’s essential to make sure there is nothing dangerous left lying around that may harm them. Fencing/netting staples and small offcuts of poultry fence wire are good examples. Swans are notorious for getting poisoned when they mistakenly pick up lead pellets, that anglers use on fishing lines.

Insoluble poultry grit

Flint or granite grit

“As rare as hen’s teeth” is a saying that most of us have heard. Well, the closest thing you can get to hen’s teeth is insoluble grit, derived from flint or granite that our chickens will store and use to grind down food in their gizzard mechanically.

Flint Grit

Unless poultry is fed exclusively on formulated layers feeds (which dissolve quickly and don’t need grinding down), then we must provide access to insoluble poultry grit for our hens to be able to digest their food fully.

Pasture fed chickens will often pick up enough natural grit themselves, although not all types of ground contain the right sort of grit, so it’s always a good idea to provide a chicken grit feeder just in case. They will help themselves with what they need. Confined chickens cannot find their grit, so they will need it to be fed to them as part of their diet.

Insoluble grit, as the name suggests, does not get digested. It is stored in the gizzard but will eventually pass through and get replaced.

Grit size

Poultry grit has to be a suitable size for the size of the bird. Grit that is too small will pass straight through the bird and will not help the bird at all, so it is worth checking that the grit you are buying is for the correct size bird.

You can buy poultry grit suitable for chicks, growers, layers and turkeys. It is better to feed a grit that is slightly too big than too small. I have included some links to suppliers below.

Soluble poultry grit

Limestone or oyster shell grit

The second type of grit you can buy for chickens is known as soluble grit. Soluble grit is limestone or crushed seashells, such as oyster and cockle shells. It is mostly made up of calcium and comes in relatively large pieces compared to insoluble grit.


Chickens need calcium for bone formation; however, eggshells consist of calcium carbonate, so laying hens need calcium to lay eggs. A hen will need to supply nearly 2.5 grams of calcium for every egg she produces.

Although generally speaking, complete layers feeds contain sufficient calcium for the average hen, if you provide them with greens and other treats, their ‘complete’ diet is diluted, causing an unbalance. Hybrid laying hens and ex-battery hens who lay large numbers of eggs may also need extra calcium in their diet.

If sufficient calcium isn’t available, a hen will start to use calcium from her bones. If this continues, the sternum and rib cage can become deformed, and bones become weak to the point where she may break them. Commercially, this is called cage layer fatigue.

Oystershell grit in a hand
Oyster shell grit, used as a calcium supplement.

It is essential to balance a hen’s diet correctly (see feeding chickens for more details) and provide free access to a chicken grit feeder containing soluble grit if she should need additional calcium.

Chicken grit feeders

Some poultry keepers will add a handful of grit in with their bird’s feed, but it is usually better to give grit to birds in a specially made hopper on an ad-lib basis. If mixed with feed, birds will usually flick it out to get to their food, and you will suffer from more waste in this way.

Grit Hopper
I have even used plant pots burried in the ground for flint grit.

There are several types of chicken grit feeder available. Any container could be used, plastic or metal, and it could be mounted in the house or run, it doesn’t matter, the chickens will find it when they need it.

Chicken Grit Feeder

This chicken grit feeder has segments inside that allows you to separate different types of grit if you wish.

Chicken grit feeder
Topping up oyster shell in one of my old galvanised chicken grit feeders

It doesn’t matter if poultry grit gets wet from the rain (providing the container can drain freely), but it is better to have it in a covered grit feeder so that your birds don’t leave droppings in there for you to clear away!

Crushed eggshells as soluble grit

Since eggshells are mainly made up of calcium carbonate, it is also possible to grind up eggshells, bake them, and feed them back to your chickens as an alternative calcium supplement, rather than purchasing oyster shell grit.

Crushed Eggshells

Crush the eggshells, then bake them in the oven for 5 to 10 minutes until they are crisp.

By baking them, you are killing off any harmful bacteria, and when they are dry, they can be stored for use later.

Never feed broken eggshells to your chickens without first crushing and baking them because this could encourage your hens to start egg-eating, which once it starts, is a difficult vice to cure

Mixed poultry grit

The two types of poultry grit above are available separately in bags of various sizes, and you can mix them in a chicken grit feeder. Still, mixed poultry grit is also available in packs of different sizes, and I find one bag is more straightforward to store than two.

Jondo Mixed
Poultry Grit

Probably one of the most popular brands of mixed poultry grit in the UK comes from JONDO.

John J. Doe & Son is a third-generation family business that has been making grit at their site, 6 miles west of Lincoln, since 1942.

A 25Kg bag may seem like a lot, but keep in mind that grit is heavy, so this is a good size for most small backyard flocks.

Carrying Jondo Poultry Grit

If you feed mixed grit, then, from time to time, check that there is enough of both types available. Sometimes hens need more of one than another, and you will need to top up the one that’s missing, or re-fresh the grit hopper with more mixed poultry grit.

I hope this article on poultry grit was useful, feel free to leave me a comment below with any additional information or questions you may have.

Related Posts:

Feeding Chickens
Keeping Chickens
Feeding Chickens

Domesticated chickens, especially modern hybrids, are fantastic egg layers; however, this performance increases nutritional demands, so how we feed our

Read More »
Feeding Chickens

Domesticated chickens, especially modern hybrids, are fantastic egg layers; however, this performance increases nutritional demands, so how we feed our

Read More »

On this page:

You might also enjoy:

Feeding Chickens
Keeping Chickens
Feeding Chickens

Domesticated chickens, especially modern hybrids, are fantastic egg layers; however, this performance increases nutritional demands, so how we feed our

Read More »