Thin eggshells are a common problem in backyard chicken flocks and can be caused by heat stress, poor nutrition, age, disease, or genetics. While an occasional weak shell isn’t usually a cause for concern, frequent thin-shelled eggs may signal that your hens need dietary or management changes. Here’s what causes thin eggshells and how to help your flock produce stronger eggs.

Key Takeaways

• Thin eggshells are commonly caused by heat stress, poor nutrition, calcium or vitamin D3 deficiencies, disease, genetics, or aging hens.
• Thin eggshells and shell-less eggs are different. Thin-shelled eggs have a fragile calcium shell, while shell-less eggs are enclosed only by a protective membrane.
• A balanced layer feed and free-choice oyster shell help hens get the calcium they need to produce strong egg shells.
• Hot weather can contribute to thin eggshells by reducing feed intake and increasing stress, which limits calcium available for shell formation.
• Persistent thin eggshells may indicate an underlying health problem. If multiple hens are affected or the issue continues despite proper nutrition, consult a poultry veterinarian.

Eggs with No Shell vs. Thin Eggshells: What’s the Difference?

Eggs laid with a thin shell are often confused with eggs laid with no shell. Eggs that have been laid without an eggshell are encased in the membrane (the clear layer of shell that protects the egg from bacteria and other harmful pathogens). Eggs laid without shells are usually messy to clean and fall apart when you try to pick them up.

Thin eggshells are eggs with an actual calcium shell. But unlike a “normal” egg, the shell is very weak. You might also notice that if you tap one finger gently on a thin-shelled egg, it leaves a permanent indent.

What Makes Strong Eggshells?

To get a better understanding of what causes thin eggshells, let’s take a closer look at what it takes to make a good-quality eggshell. Eggshells consist of five ingredients: calcium carbonate, magnesium carbonate, calcium phosphate, and soluble and insoluble proteins. While the other ingredients play a part in shell health, calcium carbonate makes up ninety-five percent of the shell’s structure.

Hens need to consume two grams of calcium carbonate for each egg that is laid. Without an adequate supply of this nutrient, a hen’s body cannot develop a good quality shell. To ensure your flock is receiving enough calcium carbonate in their diet, offer free choice of oyster shell alongside layer feed.

What Causes Thin Eggshells?

The six most common causes of thin shell eggs are summer heat, poor nutrition, lack of calcium, genetics, disease, and old age. Narrowing down the cause can be a bit tricky, so let’s take a closer look at each of these causes.

Summer Heat

Sudden heat waves are the leading cause of hens laying thin eggshells. The heat causes stress on a chicken, causing her body to send eggs down the reproductive tract faster than normal. This results in a thinner-than-normal eggshell.

During heat waves, laying hens consume less feed than normal. While this is perfectly normal, less feed intake means a decrease in calcium absorption.

Poor Nutrition

If your flock of healthy young layers are laying eggs with weak shells, it might be time to take a closer look at their diet. Chickens forced to forage for all their dietary needs or flocks fed high amounts of treats or consuming non-layer feed can quickly begin to show signs of a lack of calcium in their diet.

The lack of calcium is not only bad for egg production, but it can also cause other serious health conditions, including rickets and cage layer fatigue.

Lack of Calcium or Vitamin D3 in the Diet

Lack of calcium in the diet is a common problem in backyard layers. Without a supplemental calcium source, such as oyster shell, laying hens can quickly become depleted of calcium. But calcium isn’t the only nutrient needed for healthy eggshells.

Vitamin D3 and phosphorus help a chicken’s body to absorb calcium and produce healthy eggs. These ingredients should be found in a complete layer ration. Recommended amounts: Vitamin D3 800 ICU/lb minimum. Phosphorus (P) 0.45% minimum.

Poor Genetics

Just like humans, every chicken has its own genetic makeup. Some chickens have good genes, while others do not. Chickens with poor genetics can be prone to a serious health concern called “calcium metabolism disorder.” This condition causes a hen’s body to not absorb calcium correctly, resulting in weak eggshells and other health problems.

Note: Avoid breeding chickens suffering from calcium metabolism disorder, as it can be hereditary.

A Sign of Disease

Thin eggshells are often one of the first signs that something may not be right in your flock. Especially if the condition is affecting more than one member in the flock. Internal parasites, coccidiosis, egg laying disorders, and other diseases can weaken eggshells.

If you notice one or more of your flock consistently laying thin eggshells, contact your local poultry vet to help you narrow down the cause.

Old Age

As a hen ages, her reproductive system will begin to show wear and tear. Older hens who have past their egg-laying prime will often lay eggs with weakened eggshells. While this can be a sign that something isn’t right in the reproductive tract, many times it is just her reproductive system showing its age.

How to Prevent Thin Eggshells

Preventing weak eggshells isn’t always possible, but these tips can help cut down on the number of poor-quality eggs.

1. Feed laying hens a good-quality layer food with a good amount of calcium, phosphorus, and vitamin D3 for strong shells.
2. Limit treats to ten percent of your flock’s daily diet.
3. Allow unlimited access to free-choice oyster shell to ensure hens are receiving enough calcium.
4. Avoid breeding layers prone to laying thin eggshells.
5. Watch your flock daily and be sure to note any strange behaviors. If hens appear eggbound or sick, contact your local poultry vet right away.
6. Provide shade and access to fresh, cool water during hot spells to help chickens stay cool and feeling their best. Allow plenty of ventilation in the coop to keep your flock cooler and feed consumption up.

Should You Feed Eggshells Back to Chickens?

Feeding recycled eggshells to your laying hens may sound like a great way to save money and reduce waste, but it can cause more harm than good. Although their eggshells are usually a good source of calcium, if your hens’ bodies are depleted of calcium, their eggshells will be too.

When hens are laying thin eggshells, switch their calcium source to oyster shell to ensure your flock is receiving enough calcium to keep them and their eggs healthy.

Frequently Asked Questions

Why are my chickens laying thin eggshells?

Lack of calcium or vitamin D3 is the most common cause of weak or rubbery shell eggs.

How do you fix thin eggshells?

Feeding hens a good-quality layer feed is the best way to fix and prevent thin eggshells. Other tips include reducing stress and limiting treats.

Does the age of the chicken matter?

Yes, a chicken’s age should be considered when dealing with thin or rubbery eggshells. The older the hen is, the more likely she is to lay thin-shelled eggs.

Can too many treats cause chickens to lay thin-shelled eggs?

Yes. Consuming too many grains, fruits, and vegetables can cause chickens to lay eggs with a poor-quality shell. The more treats a chicken consumes, the less layer feed she will eat, resulting in an improper diet and thin eggshells.

Can hot weather cause thin eggshells?

When temperatures soar and humidity rises, it isn’t uncommon for a chicken to lay a few eggs with weak shells. Ensuring your flock has access at all times to fresh, cool water and ensuring good airflow and shade in the coop and run can help reduce stress and the chances of soft-shelled eggs.

Final Thoughts

Thin eggshells are often a sign that your hens need a little extra attention, whether that’s better nutrition, relief from heat stress, or a closer look at their overall health. By feeding a balanced layer diet, offering free-choice oyster shell, and monitoring your flock for signs of illness, you can help reduce thin-shelled eggs and keep your hens producing strong, healthy eggs.

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