Why Did My Chicken Lay an Egg Without a Shell?

If you've been keeping chickens for a while, then going out to the coop and retrieving eggs from the nest boxes is routine—until you pick up an egg that isn't hard. Looking closely, you realize this egg appears not to have a shell. Surprise! Your chicken really did lay an egg without a shell. You may worry that something is wrong with your hen, or that you've done something wrong in caring for her. Don't panic! It might not be a big problem; let's take a look at what is happening.

What is an egg without a shell?

That shell-less egg may look normal, and it might have the proper egg shape. But what's holding it all together? The answer is the pair of membranes that usually reside under the shell.¹ If you ever cook hard-boiled eggs, you're probably familiar with peeling away these membranes along with the shell. With shell-less eggs, the rest of the egg's normal components are present; the membrane is what's holding it all together. (It's also possible to find eggs with either very thin or incomplete shells.)

Why does it happen?

There are a few reasons why a chicken might lay an egg without a shell:

• It just happens sometimes. If this is a single occurrence, you may not be able to figure out why it happened. There's not always an explanation for it when it occurs rarely.
• Low calcium. Eggshells contain calcium carbonate—the same compound that makes up materials like seashells and chalk. To produce proper eggshells, a hen needs to have a sufficient amount of calcium in her body. If she doesn't, this can lead to trouble when forming eggshells.
• The hen is young. It's not at all uncommon for pullets that are just beginning to lay eggs to produce a couple of eggs without the shell.
• The hen is old. Older hens may start to produce these types of eggs as part of the natural aging process.²
• Stress. If an event that your hens perceive as frightening occurs during the egg-producing process, it can temporarily disrupt the final product.
• Physical ailment. There could be a health issue with your hen that is causing the shell-less eggs.

What can you do?

There are several things you can try to help your chicken produce eggs with shells:

• Keep an eye on your hen if she is otherwise healthy and the issue doesn't reoccur. There may not be any additional action required.
• Switch chicken feed. Growing chicks are often fed a “chick starter" feed specially formulated for youngsters, instead of the “layer" feed given to mature hens that are producing eggs. Part of the difference between these two products is the calcium content. The laying feed contains more calcium to help the hens produce eggshells. Be sure to switch your young hens to layer feed when they're ready to start producing eggs—usually around 18 weeks of age (although they don't reach full laying potential until they are about 25 weeks old).
• Consider putting your hens on a free-choice oyster shell supplement regimen.³ This will provide considerably more calcium than their feed alone and may even help them produce stronger eggshells in general.⁴
• Ensure your hens are getting enough vitamin D. This is needed to help their bodies utilize the calcium.
• Try to keep your hens as stress-free as possible. Keep them safe from heat, predators, “scary" noises like loud children or barking dogs, etc.
• Stay on top of your hen's health. Provide them with veterinary care as needed, fresh water, protection from heat and cold, etc.

A chicken that lays an egg without a shell can be surprising, but it often indicates something else is amiss. With a little know-how, you can help your hens stay healthy, happy, and producing eggs with that all-important shell.

2. Armitage, Neil. Cluckin.net. “Why are my chickens laying soft or thin-shelled eggs?" 18 October 2019, https://cluckin.net/why-are-my-chickens-laying-soft-or-thin-shelled-eggs.html

3. Roberts, Jason. Know Your Chickens. “Feeding Oyster Shell to Backyard Chickens," 25 April 2020 https://www.knowyourchickens.com/oyster-shells-for-chickens/

4. Mormino, Kathy Shea. Hobby Farms. “Use Oyster Shells to Give Your Chickens Stronger Eggshells," 4 December 2018, https://www.hobbyfarms.com/oyster-shells-chickens-hens-stronger-eggshells/