oyster shells for chickens

10 Surprising Benefits of Feeding Oyster Shells for Chickens

The Complete Guide on Feeding Oyster Shells for Chickens

If you’re a poultry keeper, you know how important it is to keep your chickens healthy and happy. One of the key factors in maintaining your flock’s well-being is providing them with a balanced and nutritious diet.

And when it comes to laying hens, there’s one nutrient that’s especially important: calcium.

Calcium is essential for strong eggshells and healthy bones, and it’s especially crucial during the laying period when hens are producing eggs.

If your chickens don’t get enough calcium, they may start laying thin-shelled or soft-shelled eggs, or even develop serious health issues.

One natural and effective way to ensure that your chickens get enough calcium is to feed them oyster shells. Oyster shells are a rich source of calcium carbonate, which can help promote strong eggshells and prevent calcium deficiency in your flock.

In this article, we’ll explore the amazing benefits of oyster shells for chickens and provide expert tips on how to feed them to your feathered friends.

oster shells for chickens

What Are Oyster Shells

Oyster shells, as the name suggests, are the hard, protective coverings of oysters. They’re composed primarily of calcium carbonate, which makes up around 95% of the shell’s total weight.

Oyster shells are similar in composition to other types of calcium supplements, such as limestone or eggshells, but they’re often preferred by poultry keepers due to their natural origin and high bioavailability.

Oyster shells are typically sold in crushed or powdered form, and can be easily mixed with your chickens’ regular feed. They’re also available in whole form, but these may need to be crushed or ground up before feeding.

It’s important to note that not all oyster shells are created equal. Some oyster shells may contain high levels of heavy metals or other contaminants, which can be harmful to your chickens.

To ensure that you’re feeding your flock safe and high-quality oyster shells, it’s important to purchase them from a reputable supplier.

Oyster shell is simply the ground up shells of oysters, as the name implies.

Commercial oyster shells for chickens may occasionally contain other types of shell, but most of the time it’s just plain old oyster.

Oyster shell, also known as soluble grit, is high in calcium.  Many feed companies will tell you that commercial feed is sufficient to meet the needs of your chickens.

While this is probably true if you are raising broiler chickens, it is probably not something you want to risk finding out on your own if you are raising laying hens.

Some layer feeds simply don’t contain enough calcium for your hens, and you’ll have to wait and see how your individual birds react to find out for sure.  Why risk it?  Feed oyster shells for chickens.

An egg contains 94-97 percent calcium carbonate, which must all be extracted from the bodies of your chickens.

If you have chickens that lay frequently, such as every day or every other day, they will require more oyster shell than those that lay only a couple of times per week.

Why Do Chickens Need Oyster Shells?

oyster shells for chickens

Calcium plays a critical role in many aspects of chicken health, including egg production, bone strength, and muscle function. In laying hens, calcium is especially important for the formation of strong eggshells.

Without enough calcium, hens may lay eggs with thin or soft shells, which can lead to breakage, deformities, or even internal egg laying (also known as egg binding).

In addition to egg production, calcium is also important for maintaining strong bones and muscle function in chickens. Calcium deficiency can lead to a range of health issues, including weak bones, muscle spasms, and even seizures.

Over time, chronic calcium deficiency can also increase the risk of serious health problems like osteoporosis or fatty liver disease.

Fortunately, feeding your chickens oyster shells can help prevent calcium deficiency and promote overall health.

Oyster shells are a highly bioavailable source of calcium carbonate, which means that they’re easily absorbed and utilized by your chickens’ bodies.

While most chickens will benefit from eating oyster shell, not all will.  For instance, hens that aren’t laying yet probably don’t need to be fed oyster shell.

In a single year, a hen will deposit twenty times as much calcium into her eggs as is present in her bones.

That’s a lot of calcium!

Having said that, laying hens will gain from the following:

  • Calcium supplementation lowers the chance of egg cracking
  • Decreased possibility of bone damage
  • Blood vessel strength is increased
  • Improves and protects the immune systems of your chickens
  • Strengthens the heart and blood vessels

Diet has a significant impact on egg production, just like it does for other egg-producing species, including mammals.

When it comes to the effects of nutritional deficits, a chicken is especially sensitive. She needs plenty of calcium to produce a robust egg shell.

How to feed Oyster Shells to chickens

Feeding oyster shells to your chickens is easy and straightforward. Here are some tips to get you started:

  1. Offer oyster shells free-choice: The easiest way to give oyster shells for chickens is to put them in a separate container and let them eat them whenever they want. This lets your chickens control how much food they eat based on their own needs.
  2. Mix with feed: You can also mix crushed oyster shells right into the food your chickens already eat. This is a good idea if you have chickens that are picky eaters or if you don’t want some chickens to get more or less than their fair share.
  3. Provide adequate water: So they can digest their food and supplements well, chickens need a lot of clean, fresh water. Make sure that your flock always has access to clean water.
  4. Monitor intake: You should watch how much oyster shells your chickens eat to make sure they get enough but not too much. Too much calcium in the diet can cause health problems like kidney stones or gout, so it’s important to find a good balance.
See also  10 Amazing Ways to Prevent and Avoid Egg Bound Chickens

In general, most laying hens will require around 1/4 to 1/2 cup of oyster shells per week, depending on their size and age.

It’s always a good idea to consult with a poultry expert or veterinarian if you have any concerns about your flock’s health or nutrition.

What Are Some Alternatives to Store Bought Oyster Shells?

There are many other options for high-calcium foods that you can feed your laying hens if you don’t want to buy commercial oyster shell.

1.Cooked, Ground Up Egg Shells

It may sound macabre, but recycling eggshells by feeding them back to chickens is a great way to reduce waste and give your girls a healthy dose of calcium.

You don’t want your chickens to develop the bad habit of thinking that eggshells are food and eating them, so avoid giving them full egg shells.

Some people are concerned that feeding egg shells to chickens could result in bacterial infections.

You shouldn’t have to worry about bacteria infecting your chickens if you cook your shells down before grinding them into a powder.

In order to prevent your chickens from trying to eat the shells, you should cook them first.

The calcium content of chicken eggs may not be as high as you’d like it to be if your chickens are eating a diet low in calcium.

In order to get your hens back into fighting shape, you may need to feed them the egg shells of other birds.

Eggshells do not contain the same fast-release source of calcium as oyster shells, which is another minor issue with feeding eggshells to chickens as an alternative to oyster shells.

They’re still helpful, and they’re a good source of calcium—you just have to feed them more frequently if you want to get the most out of this way.

2.  Limestone that has been crushed

This form of calcium is widely used in commercial laying feeds, but it is also available for individual purchase.

Feeding dolomitic limestone, which contains more magnesium and can inhibit calcium absorption, requires caution.

3.  Calcium-Rich Feeds

Some layer feeds contain enough calcium for your chickens.

To specifically address this requirement, there are commercial feeds that are higher in calcium.

However, it is advised to avoid feeding this type of food to a flock of chickens that consists of both laying and non-laying chickens in order to avoid excess calcium.

Look for a layer feed with at least 16% protein and more calcium.

When your hens reach about 18 weeks of age or when the first egg is laid, whichever comes first, you can start feeding them these.

Don’t give layer feed to chickens that don’t need it, though.

4.  Home-made Oyster Shells for Chickens Feed

If you want to save money, you can buy bags of ground oyster shells from feed stores, but you might also want to try making your own oyster shell supplement.

In most cases, this is not practical; purchasing oysters solely to create oyster shell feed is not worthwhile.

However, if you have access to a large quantity of free oyster shells, this is a great way to reduce your overall feed bill.

If you’re curious about what happens to used oyster shells, you should inquire at a nearby restaurant.

They typically just discard them.

You might be able to get out of this at no additional cost to you if they’re willing to save them for you.

Start by baking the shells for about 10 minutes at 250 degrees Fahrenheit to prepare the feed for your chickens.

This can be done on a baking sheet. The mold and other pathogens on the shell will be killed in the baking process, and the shells will be easier to crack and work with.

Put the shells in a bag after baking them. To break the shells up into smaller pieces, smash the bag with a hammer or even drive over it with your car.

This won’t take very long at all. The shells can then be ground up in a blender or food processor to create a powdery supplement. That’s all there is to it!

5.  Table Scraps

Increasing your hen’s calcium intake is as simple as feeding her a few of these common household foods.

All of your chickens, not just the layers, will benefit from scraps, making for a more balanced, easily digestible treat.

Here are some foods that are high in calcium:

  • Spinach
  • Sardines and Salmon
  • Swiss Chard
  • Mustard greens
  • Kale
  • Garlic
  • Yogurt
  • Dandelion Greens
  • Red clover
  • Brussels sprouts
  • Broccoli
  • Cooked Beans
  • Cheese
  • Milk
  • Shellfish
  • Basil
  • Rhubarb
  • Cabbage
  • Summer Squash
  • Orange Juice

6.  Vitamin Supplements

This won’t necessarily give your chickens any more calcium and shouldn’t be used as a replacement for supplemental calcium.

However, giving your chickens more vitamin A, E, and D can increase their calcium absorption compared to feeding them calcium alone.

These supplements, which are available in powder form, should be mixed into their daily water intake.

You don’t need to worry about providing separate watering systems for roosters or young chickens because they won’t harm non-laying birds.

7.  Sea Shells

Incorporating seashells into egg production has some tangible benefits.

The most important advantages of using seashells are:

  • Reduced egg breakage
  • Chicken deaths have decreased.
  • A slow release time and low solubility
  • Low levels of heavy metals
  • Enhanced weathered edges
  • Sterilized and heated
  • Pays off itself

Solubility of Sea Shells

It is recommended that the calcium in poultry feed be released slowly over time in the intestines. Calcium absorption by the chicken depends on the particle size.

Ingredients high in calcium that are both poorly soluble and have a large particle size will spend more time in the gizzard, increasing the amount of calcium the chicken is able to absorb.

See also  5 Important Things You Didn't Know on What do Baby Chickens Eat?

In comparison to ground material, the eggshell strength of chickens that were fed a mined marine calcium source as a hen-size particle was found to be significantly higher.

When tested against oyster shells, coarse limestone, finely ground limestone and sea shells,  the latter were found to be more acid-resistant over the former two.

This means fewer issues with bone health and less reliance on calcium mobilization from bone in laying hens.

In a 17-week feeding trial, hens given either a limestone-based supplement or seashells produced 26% more eggs with fewer breakages and lower mortality rates than hens given a placebo.

Over the course of 17 weeks, mortality for hens fed the limestone supplement was 12.4%, while it was only 2.6% for hens fed seashells.

When compared to the supplemented group, which had a 1.7% hatch rate, the limestone group’s 2.1% rate was significantly higher.

Lesser Heavy Metal Levels

Heavy metals, such as lead, cadmium, and others, can accumulate in oysters because they absorb their surroundings, and oysters harvested from polluted waters are especially at risk.

Chickens are less likely to be poisoned by eating seashells from natural sources like the Caspian Sea because they contain lower levels of these metals.

Smoother Edges

In addition, seashells found in their natural deposits typically have rounded, weathered edges that make them easier to digest and less likely to cause internal damage to the chicken.

Safe and Heat-Treated

The risk of salmonella and E. coli contamination in poultry is reduced because seashells are heat-treated and sterilized to ensure the product is free of contamination, whereas oyster shells are typically not.

oyster shells for chickens

Advantages and Disadvantages of Feeding Oyster Shells for Chickens


Advantages of Oyster Shells for Chickens

A sufficient supply of calcium is essential for hens to continue laying eggs, preserve bone health, and produce eggs of high quality and resilience.

As a result, oyster shells, in addition to mined limestone, are commonly used as a feed supplement for laying hens to prevent the mobilization of calcium from the bones.

For what purpose are oyster shells so popular? Calcium content in commercially available oyster shells averages around 38%; however, the amount of calcium available to the hen depends heavily on particle size.

Oyster shells with larger particle sizes (2-4 mm) have been shown to decrease calcium mobilization from the bones and increase egg quality and production.

Disadvantages of Oyster Shells for Chickens

Oyster shell is often more expensive than limestone, and many smaller feed mills do not have the resources to or simply do not choose to include coarse calcium in their chickens’ diets.

The cost of feed accounts for roughly 60%- 70% of the total price of producing eggs. Both egg producers and consumers would benefit from a switch to a cheaper source of calcium with the same physical properties.

What Are the Signs That Chickens Need More Calcium?

If you’re new to raising chickens, you might assume that the feed you purchase from the pet store will suffice.

This is usually the case, but if you’ve observed any of the following issues with your chickens, you may want to consider giving them some extra calcium.

Bone damage:

Have you had a hen suffer a broken bone or a joint injury in the last few weeks? If so, a calcium deficiency may be to blame.

A hen will take calcium from her bones if she doesn’t have enough calcium to build an egg shell. She may develop osteoporosis as a result and have difficulty getting up and down.

Problems in Behaviour:

Pecking and increased activity are two signs of calcium deficiency in chickens. Some of your flock members may suffer serious harm or even perish as a result of this.

Soft egg shells:

If the shells of your chickens’ eggs are soft, squishy, or missing altogether, it’s time to add calcium. A calcium-rich diet is necessary for a hen to produce eggs with a tough shell.


Chickens that appear to have stiff legs or who are lame may not be suffering from bone damage brought on by a lack of calcium. Even in non-laying chickens, these early symptoms may be indicative of calcium deficiency.

Reduced egg production or hens that don’t start laying:

Has the laying age of your hens passed? Or did they stop laying altogether (or slow down)? If so, a calcium deficiency may be to blame.

Ideal Frequency of Feeding Oyster Shells for Chickens?

oyster shells for chickens

Give your laying hens free access to oyster shell by placing it in a bowl or a separate feeder.  While you can add oyster shell to the feed, you run the risk of giving chickens who don’t need oyster shell too much calcium.

The best approach is to let the birds control their own calcium intake.  Place an oyster shell in a bowl next to the chicken feed. Your hens will determine how much and when to eat.

When it runs out, just fill it back up. A typical hen will consume about 100 grams of feed containing 4% total calcium per day.  Throughout the year, regardless of the season or the weather, you should consistently feed oyster shell.

When your hens are molting, broody, or resting over the winter, you shouldn’t stop giving them oyster shell.  It will help to strengthen their bones and allow them to lay more eggs later in the season.

A chicken’s digestive system can process food in 90 minutes.  The calcium will quickly enter your hen’s bloodstream while she is awake and eating.

An egg is produced by a hen in about 25 hours (there is some variation here among breeds).  In order to ensure that her body is always prepared to produce a hard shell, she should have consistent access to calcium.

What Is the Nutritional Value of Oyster Shells for Chickens?


The calcium in oyster shell is exactly what your chickens need to produce healthy eggs.  Low calcium levels in hens increase the risk of soft or no shell eggs and bone fractures, especially in the feet and legs.

As was previously stated, egg shells are composed almost entirely of calcium carbonate.  A hen’s feed must provide nearly all of the calcium required to create a healthy egg shell.

To get the two grams of calcium required to make one egg shell, she should consume about four grams of calcium per day.  The larger your hen, the more calcium she will need.

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When your chickens eat oyster shell, their bodies separate into calcium and carbonate components in the hen’s intestine.  They will then enter the bloodstream and travel to the shell gland, with any excess being stored in the bird’s bones.

Hens actually have special bones called medullary bones that store calcium, which helps to make them stronger and more stable.

Should You Feed Oyster Shells for Chickens That Aren’t Laying Yet?

The following types of chicken are safe to feed oyster shell to:

  • Chicks
  • Pullets that haven’t started laying eggs
  • Older chickens that have stopped laying eggs
  • Roosters

Keep your oyster shell separate if you are raising a mixed flock of birds so that the birds that require it can access it.

This will stop overfeeding the birds who don’t need oyster shell. Small amounts of extra calcium won’t hurt these chickens, but too much can be harmful.

Potential calcium overdose effects include the following:

  • Failure of the kidneys
  • Calcium absorption problems over time (as a result of an overloaded system)
  • Leg abnormalities
  • Metabolic problems
  • Having trouble absorbing phosphorus and vitamin D
  • Egg Binding
  • Joint issues

Chickens should not be given oyster shell until they are at least 18 weeks old. Only hens who are laying eggs should use oyster shells.

Keep in mind that your hens will only eat as much calcium as they need, but if you add calcium to their food before they’re ready for it, it can cause serious kidney damage.

Oyster Shells for Chickens vs. Grit: What’s the Difference?

Many farmers mistakenly believe that grit and oyster shell are the same thing and will have the same effects on their backyard flocks of chickens.

Both are important to the health of your birds, but they serve different purposes. Without either, serious health problems could develop in your flock, reducing productivity and quality of life.

What You Need to Know About Grit for Chickens

osyter shells and grit for chickens

Grit aids in the digestion of food for your chickens.

Chickens need a way to break down their food into smaller, more manageable pieces because they lack teeth.  This is made possible by their grit.

The gizzard receives the grit that your chickens eat. It remains there for some time, waiting for the chicken’s digestive system to wear it down to the point where it can be safely passed through.

It aids in the reduction of food to a paste while it is present.  Your chicken’s digestive system will then take in all the water and nutrients it requires before eliminating it.

Grit helps transform food into something that is more easily digested and utilized by the body of your chicken.

Chickens will have a difficult time digesting food if they don’t have access to grit, either in supplement form or in their natural environment.

The feed store sells grit. It’s essentially just broken granite or flint. It has no expiration date and is reasonably priced.

Grit should be given the freedom to choose. Free-ranging chickens can provide all the grit they require, but it all depends on the type of soil you have and how much space you give them.

Oyster Shells

Because oyster shell is frequently referred to as soluble grit, people frequently confuse it with grit.

It is easily digested and stored in the hen’s body, where it is used to strengthen the egg shell and improve the hen’s overall health. Grit cannot dissolve in the gut, but oyster shell can.

The primary goal of this supplement is to increase the calcium intake of your laying hens, though it may also aid in digestion.

The conclusion? The two serve very different (yet equally important) roles in the health and well-being of your chickens, even though you must feed them both oyster shell and grit.

The Importance of Oyster Shells for Chickens

If you’re thinking, “Yeah, yeah, enough already. We understand. You are correct that your chickens require more calcium.

They do!

However, the truth is that a lack of calcium has an impact on you as well as your chickens.  You undoubtedly keep laying hens because you want to eat (or sell) the eggs.

The best way to stop bacteria from entering an egg is through its shell.  A disease-carrying egg shell is much less likely to survive pressure from the outside world.

You probably shouldn’t be considering that while eating breakfast.

Instead, think about putting down a pan of oyster shell the next time you’re in your chicken coop. It will be greatly appreciated by your chickens.


Final Thoughts

In conclusion, oyster shells are a good supplement to think about for the health and well-being of your flock.

By giving your chickens a calcium source, you can help make sure that their eggs are formed right and that they are less likely to get sick.

When giving oyster shells to your chickens, it’s important to keep an eye on how much they eat and give them plenty of clean water.

You can give them oyster shells as a free-choice supplement or mix them into their regular feed. If you have any questions or concerns about your flock’s health or nutrition, talk to a poultry expert or veterinarian.

In addition to oyster shells, your chickens need a balanced and varied diet with lots of protein, vitamins, and minerals.

Your chickens will be happier, healthier, and more productive if they eat well, move around often, and live in a good place.

We hope that this article has helped you learn more about how important oyster shells are for chickens.

If you take good care of your flock and give them the right supplements, you can help make sure they do well and keep giving you tasty, healthy eggs for years to come.





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