If you are a poultry keeper, you understand the importance of calcium to chickens.

Without sufficient calcium, chickens will not lay eggs with strong eggshells and might develop brittle bones.

Perhaps the most reliable source of calcium for chickens is oyster shells. To many people, these humble shells are just remnants of seafood feasts. But to your flock, they are a gold mine, more like a calcium mine.

But when should you give chicken oyster shells?

Well, that’s where we come in. In this post, we will discuss the nutritional benefits of oyster shells and how they might affect the productivity of your flock.

So, keep reading to uncover the incredible rewards these shells offer.

Is Oyster Shells Safe for Chickens?

Yes! Crushed oyster shells offer chicken owners a reliable way to provide their flock with sufficient calcium.

Like humans, backyard chickens need a well-balanced and nutritious diet to thrive. One vital component of a chicken’s diet is calcium. It’s an essential mineral crucial for the formation and maintenance of strong bones.

Calcium also plays an important role in nerve function and muscle contractions.

Why Should You Give Chickens Oyster Shells?

Most chicken owners believe commercial chicken feeds provide their flock with enough calcium, but that’s not always the case.

Some feeds contain negligible amounts of calcium; not sufficient to meet the birds’ needs. That’s where oyster shells come in.

An oyster shell contains high levels of calcium carbonate. This is a variant of calcium, easily absorbed by the chicken’s digestive tract/system.

You can supplement your chicken feed with oyster shells to ensure your birds receive enough calcium to support their health and well-being.

On that note, let’s highlight the various benefits of oyster shells to chickens.

1. Production of Strong Eggshells

Have you ever held an egg with a soft or rubber-like shell?

That happens because the hen didn’t receive enough calcium needed to form a strong eggshell.

Here’s something you didn’t know:

The eggshells comprise a significant amount of calcium carbonate, which ranges from 90 to 95%. This essential mineral is behind the formation of strong and sturdy eggshells.

Surprisingly, a hen can deposit 20 times the amount of calcium found in her bones into her eggshells within a year.

If you ask us, that’s an astonishing amount of calcium. So, if you want your layers to produce eggs with robust and durable eggshells, they need a consistent supply of calcium.

What better way to provide your laying hens with calcium than oyster shells? Sure, they might get this essential mineral from their layer feed. But that’s if the feed is the only food they can access.

However, if your chickens are free-range or you feed them with kitchen scraps, supply them with additional calcium.

Without the supplemental calcium, eggshell quality will suffer. As a result, they will produce eggs with thin shells. Sometimes, the eggshells might develop some deformities or break inside the hen.

And that’s just the tip of the iceberg.

Besides egg formation, hens need calcium for the muscle contractions required to push the eggs out.

Without enough calcium, the muscle will not have enough energy to expel the eggs. Because of this, the egg might get stuck somewhere in the reproductive system.

This might lead to a fatal condition known as egg-binding or dystocia.

2. Promote Strong and Healthy Bones

Promote Strong and Healthy Bones
Image Credit: wyldsonshomestead

In chickens, calcium promotes the development and maintenance of strong bones. The mineral supports the structural integrity of their skeletal system and mobility.

Additionally, sufficient calcium levels maintain healthy bone density and reduce the risk of fractures and skeletal deformities in chickens.

Interestingly, the bones also serve as storage for calcium in the body. However, the demanding process of egg development consumes a significant amount of calcium.

If the hen’s diet lacks calcium, she will take it from her bones to aid muscle contraction and egg formation.

If the hen draws more than 2,000mg of calcium, the structural foundation of her bones might be compromised.  As a result, the bones will become brittle and highly susceptible to breakages and conditions, such as avian osteoporosis.

Luckily, oyster shells offer an affordable and effective way to provide your flock with extra calcium. This way, you can support optimal bone health, prevent joint injury and reduce the risk of fractures in your chicken.

3. Other Benefits of Oyster Shells to Chickens

In addition to the benefits above, the calcium and other minerals in oyster shells will help your birds in the following ways:

  • Supports proper nerve transmission
  • Boost the chicken’s immune system
  • Improve metabolic process
  • Strengthen blood vessels
  • Maintain cardiovascular functioning

Signs That You Should Give Your Chicken Oyster Shells

Signs That You Should Give Your Chicken Oyster Shells
Image Credit: crimp_hill_chickens

How do you know your birds need oyster shells?

If you don’t provide your chickens with oyster shells, they might display a few signs that point to calcium deficiency, including:

  • Egg Binding– Egg binding occurs when your hen is unable to push an egg from her body because of weak contraction caused by low calcium levels.
  • Reduced Egg Production–Chickens often re-locate available calcium toward the eggshell formation. Therefore, a lack of enough calcium in the body could result in reduced laying frequency.
  • Behavioral Changes–Does your chicken consistently peck her feathers? Or show signs of aggression toward other members of the flock? Chances are, you have a calcium deficiency problem in your hand.
  • Increased Egg Breakage–Squishy, soft, or light eggshells are a sign to supplement your chicken’s diet with calcium.
  • Abnormal Egg Formation – Insufficient calcium supply in the hen’s body could also lead to irregularities in the eggs’ shape and eggshell structure.
  • Weakness and Mobility Issues–Birds require calcium for proper bone and muscle functioning. But if a hen shows weakness or difficulty in moving, it could be a sign she needs more calcium.
  • Bone Damage–Oftentimes, your chicken might suffer from a bone injury or broken bone because of a shortage of calcium in the body. Calcium deficiency forces hens to extract reserve calcium from their bones, impairing skeletal integrity.
  • Lameness–Low calcium levels also make chickens susceptible to stiff legs, which lead to lameness.

Do All Chickens Need Oyster Shells?

No! Oyster shell supplement is essential for only laying hens. Layers use as much as 4 times the amount of calcium non-layers require.

Roosters, young pullets (not laying), baby chicks, and older hens (who stopped laying) can get sufficient calcium from their normal diet.

But there’s one thing you should note:

Only give laying chicken oyster shells when they display signs of calcium deficiency. If you give them too much calcium, they might develop a host of health issues, including:

  • Kidney damage and even failure
  • Leg abnormalities
  • Joint issues
  • Increased susceptibility to injuries
  • Metabolic problems
  • Depression
  • Inability to absorb calcium

Excess calcium in the hen’s diet could also lead to the formation of eggs with rough ends or speckles and reduced feed consumption.

How Much Oyster Shells Do Chickens Need?

How Much Oyster Shells Do Chickens Need?
Image Credit: cuddle.coop
Age of Chickens Amount of Oyster Shells Frequency of Feeding
Baby Chicks Not needed N/A
Pullets Start by offering small amounts Once a week
Laying Hens ¼ to ½ cup per bird per week Free choice
Roosters/ Cockerels Optional As need

The amount of oyster shells required by laying chickens will also depend on their calcium needs. The table below will elaborate better.

Stage Starter Development Pre-Laying Laying
Age 1 -4 weeks 5 – 10 weeks 11- 15 weeks 16-18 weeks
Required Calcium 0.9% of the diet 0.95% of the diet 0.86% of the diet 2.2 to 4.5% of the diet

Overall, laying hens requires 4 to 5g of calcium per day. As for pullets, they require a daily calcium intake of 2 to 3g daily.

Anything above these values is considered excess and could prove detrimental to your flock’s health.

But remember, the calcium requirement for your chicken could vary depending on factors like breed, age, and health conditions.

It also helps to consult a poultry nutritionist to ensure you provide your birds with accurate calcium supplementation.

How Do You Give Chickens Oyster Shells?

While it’s tempting to mix oyster shells with chicken feed from the food store, experts recommend against it. Otherwise, you might give your chicken too much calcium, which might lead to issues like kidney failure.

Keep in mind, chickens have different calcium needs depending on age, egg production, and health condition. For instance, baby chickens and roosters require no additional calcium because they can get it from their feed.

Therefore, it’s wise to place the oyster shells in a separate bowl or a divided feeder if you have one. Chickens that need calcium will instinctively consume as much as their bodies need. Those that don’t need this mineral might even not touch the oyster shells.

And don’t refill the dish or feeder when it’s empty.

Can Oyster Shells Be Used as Chicken Grit?

Chickens might not have teeth, but they have a super crusher or mechanical stomach: the gizzard. This part of the chicken digestive system is responsible for grinding down food and making it easily digestible.

But it can only complete its function effectively with the help of grit. Grit comprises small bits of stone, flint, granite, or gravel that birds swallow during foraging. These materials break down food into small chunks whenever the gizzard squeezes and contracts.

Oyster shells make great soluble grit like limestone and crushed cockle or mussels shells. Unlike insoluble grit, this chicken grit dissolves in the chicken’s digestive system.

As a result, it aids in digestion while providing the bird with calcium carbonate essential for bone development and egg formation.

Alternative To Oyster Shells

Alternative To Oyster Shells
Image Credit: newportchicks

Are you wondering if there are alternative options for store-bought oyster shells?

You are in luck because this section discusses several alternative high-calcium choices. Let’s check them out!

1. Crushed Eggshells

If you don’t want commercial oyster shells, you can make your own by recycling old eggshells. While it might seem cruel to feed chickens their own eggshells, it’s perfectly fine.

Since eggshells are made of calcium carbonate, they can serve as an excellent source of calcium for your birds.

Nevertheless, don’t feed your flock complete eggshells. Otherwise, they may develop a taste for their eggs, a habit that is extremely hard to break.

The best way to feed your chickens eggshells is to crush them. Next, place the grounded eggshells on a baking sheet and bake to kill any bacteria and pathogens on the surface. Baking also makes the eggshell recognizable.

The only downside with eggshells is that they are not a fast-release source of calcium, unlike oyster shells. So, you want to mix these to meet your chickens’ calcium needs.

2. Ground Limestone

Limestone is a well-recognized source of calcium carbonate. You can purchase ground limestone from your local feed store and add it to your chicken’s feed to increase calcium levels.

But be wary of the type of limestone you buy. Some, like dolomitic limestone, contain high magnesium levels. This mineral usually prevents the absorption of calcium in the bird’s body.

3. Kitchen Scraps

Some table scraps can help meet your flock’s calcium needs, including:

4. Calcium Supplements

Chicken feed stores sell commercial calcium supplements for chickens. These supplements come as pellets or powders and you can add them to your flock’s feed. Alternatively, you can offer the chickens the pellets in a separate dish.

5. High-Calcium Feeds

On the other hand, you can opt for high-calcium chicken feeds. These commercial feeds have sufficient calcium to satisfy your chicken’s dietary needs.

However, these feeds are best given to layers, not roosters or chicks. Too much calcium for non-laying chickens can prove detrimental.

Closing Remarks

Oyster shells offer chickens several benefits. For example, they serve as an excellent source of calcium. That means they promote egg formation and maintain healthy bones.

Unlike roosters, chicks, and pullets, laying hens (around 18-20 weeks) requires significant amounts of calcium. As such, they can benefit more from consuming oyster shells.

The same applies to chickens that show signs of calcium deficiency, like lameness, broken bones, and reduced egg production.

So, why not try oyster shells today? It’s just a small investment with numerous advantages. Also, your chicken will thank you with better eggshell quality and good health.

Do you have any questions? Tell us in the comment section!

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