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3 Reasons for Feeding Chickens Oyster Shells

Have you been curious to whether or not you should be feeding your chickens oyster shells? There are many important parts to a hens diet and oyster shell is definitely one of them!

Chickens Eating Oyster Shell

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For as long as I can remember, I have fed my chickens oyster shell. My grandpa who I consider an expert on raising chickens always fed his chickens oyster shell. So whatever he does I do, and it has seemed to work out perfect!

But if you’re new to raising chickens or maybe even a long time chicken owner, you may still be wondering why your chickens need oyster shell.

Why You Need Oyster Shells for Your Chickens

Feeding your chickens oyster shell is pretty important. There are other things you need to feed your chickens such as layer feed for healthy egg production and fresh herbs for health.

But always providing oyster shell for chickens to eat as they want will ensure that your hens are healthy and have a good amount of calcium. 

Below I’ll go over the three most important benefits. 

1.) Oyster Shell Produces Hard Eggshells

Nobody wants an egg that breaks in the nesting box or that simply falls apart when you handle it.

So to ensure that your hen is able to lay eggs with strong shells, she needs a diet high in calcium.

Broken Eggs Shells

Eggshells are about 95% calcium, so you can see how important calcium is for strong eggshells.

2.) It Helps Hens Stay Strong and Healthy 

When laying hens do not receive enough calcium their body begins taking it from their bones. This can then lead to weak and brittle boned chickens.

3.) Oyster Shell Will Help With Continued Egg Production

If you’ve noticed that your hens are not laying there are a few reasons to why, but one of them may be that she needs additional calcium.

Signs of calcium deficiency in hens include:

  1. Hens laying thin shelled eggs
  2. Hens laying soft shelled eggs
  3. Eggs with no shell
  4. Slow egg production.

When to Begin Providing Hens With Supplemental Calcium

First off, only laying hens need additional calcium, roosters do not.

In fact, too much calcium can be harmful to chickens that don’t use up the extra calcium to produce eggs.

The time to start providing additional calcium is around 18 weeks or once you notice that your hens have started laying.

Depending on the feed that your chickens eat, they may already get enough calcium.

Most layer feeds already have a sufficient amount of calcium.

But if your chickens are free ranging or also eating chicken scratch, they may not be getting enough calcium in their diet.

How to Feed Oyster Shell

Put ground oyster shell in it’s own feeder, providing your hens the free choice to eat it when they want.

You do not want to mix it in their feed because then chickens that do not need it will end up eating it as well.

Hens will instinctively know that they need more calcium and will eat the oyster shell as they need it.

You should be able to find ground oyster shell at your local feed store no problem, but if not they even sell oyster shell on Amazon.

Oyster shell should last quite a long time so don’t be worried by the price. But it tends to be really cheap at the feed store if you can find it.

The last large bag I bought has lasted 25 hens over 4 months.

In Addition

Grit along with oyster shell is needed in your chickens diet. They are two completely separate things and each serves their own purpose.

Oyster shell is specifically for hens that are laying to provide them with the extra calcium needed.

Poultry grit is to help all chickens put their food into a usable form.

Chickens don’t have teeth so the grit is what helps to break down their food. After a chicken eats the grit it settles in their gizzard and stays there to grind food.

More Ways for Hens to Get More Calcium

You may have heard of people feeding eggshells back to their hens. I have heard both negative and positives about doing so.

One negative belief is that hens will then try to eat their own eggs.

A positive is that you’re being resourceful and still providing a good source of calcium.

For many years eggshells have been fed back to their hens to eat and so I don’t see it as a problem. I believe that practices that have been around a long time tend to be pretty smart.

If you decide to feed the eggs shells back to your hens then just make sure that you first dry them out and crush them up.

Don’t just throw an egg on the ground and let them eat it. You don’t want them to enjoy the taste of the egg white and yolk, just the shell alone. 

Here is also a list of some great calcium rich vegetables that you can feed your hens as well:

  1. Broccoli
  2. Brussels Sprouts
  3. Butternut Squash
  4. Cabbage
  5. Celery
  6. Chard
  7. Collards
  8. Dandelion Greens
  9. Green Beans
  10. Kale
  11. Red Clover

Learn more in my YouTube video below!

For more posts on raising healthy, happy chickens check out:

The Benefits of Having a Light in Your Chicken Coop

How to Keep Your Chickens Cool in the Summer Heat

3 Benefits of Using Diatomaceous Earth for Chickens

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Chickens Eating Oyster Shell


  1. Thank you! Oyster shells can work wonders so if you are not yet feeding them to your hens you should try it out 🙂

  2. Please help. My hens are 18 weeks old. They don’t free run. I’ve always fed them the crushed layer feed and haven’t switched to pellets yet. I just introduced them to oyster shell but they don’t take any interest. They’re not laying yet and I also couldn’t find the shell in crushed form. Does it take like a week for them to eat it or is it because it’s not crushed?

    1. Hi Melody 🙂 Hens don’t need that extra calcium until they have started laying. And being that you said they are only 18 weeks old I’m assuming they are not laying yet or maybe barley have started. They will instinctively know when they need the extra nutrients, so don’t worry that they aren’t eating it. Right now with them being so young the layer feed is providing them with all the nutrients they need. Hope this helps! Let me know if I can help out more 🙂

  3. I wonder if I can use freshwater clam shell as a diy substitute for oyster. I live next to a river with a thriving clam population and see plenty of shells littered on the bottom of the river. A simple mortar/pestle to pulverize them would be easy enough to create.

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