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What Causes Soft Shelled Chicken Eggs?

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Soft-shelled or "rubber" eggs can be caused by a lack of calcium, too much spinach or a bit more uncommonly a disease. Learn the causes and how to prevent them.

The longer you raise chickens, the more chance that eventually you'll collect some odd-looking eggs on occasion. Most times, they are nothing to worry about - just a glitch in production. 

One of the more common 'glitches' is a soft-shelled or "rubber" egg. Which is to say, basically an egg laid without a shell or with a very soft shell.

You might notice a piece of membrane in the nesting box or on the ground or floor of the chicken coop. You might  notice a broken egg. Both of there are signs that you might have a hen laying soft-shelled eggs. 

What is a Soft-Shelled Egg?

Soft-shelled eggs often look and feel like water balloons, with the yolk and white covered only by a membrane, not the hard shell, but sometimes there is a shell that is just extremely thin and you can easily crack just by pressing your finger into it.

A hen needs calcium not only to form the shell around each egg she lays, but also to produce the contractions that help her to lay that egg.

And a diet that consists of good-quality layer feed plus free-choice crushed eggshell or oyster shell normally is sufficient to ensure nice hard shells.

But sometimes that's not enough. Sometimes a hen's body doesn't absorb the calcium she's getting in her diet correctly or there could be a more serious underlying issue.

So what causes soft-shelled chicken eggs?

What Causes  Soft-Shelled Chicken Eggs?


  • Young layers often lay soft-shelled eggs when they are first getting started. This should stop once their reproductive systems mature and fully develop.
  • Stress can cause a hen to lay her egg prematurely without the shell. Being chased by children, or harassed by dogs or other predators can be the cause of great stress and fright.
  • Older hens often lay thin-shelled eggs since the same amount of shell must encompass a much larger amount of yolk/white than when she was younger (eggs generally get larger as a hen ages).

  • Calcium deficiency can result in soft-shelled eggs, so be sure you provide the added calcium supplement in the form of egg- or oyster shell always fed in a separate container from the feed, so each hen can eat as much or as little as she needs.
  • A Vitamin D deficiency can also result in eggs with soft shells, so allowing your chickens time outdoors in the sunlight year round is important.
  • Far less common, soft-shelled eggs can be a symptom of such diseases as Newcastle disease or infectious bronchitis. If you are regularly seeing soft-shelled eggs, a vet should be consulted if you have ruled out all other causes.

How Do I Prevent Soft-Shelled Eggs?


  • Crushed eggshell or oyster shell should always be made available to your flock on a free-choice basis, not mixed into their feed. This way each hen can eat as much or as little as she needs.  Different hens absorb calcium differently, and depending on how good a layer she is, one hen may just need more than another.

  • Avoid overfeeding spinach, as well as beet greens, chards and citrus fruits, all of which which can interfere with calcium absorption. If soft-shelled eggs are a problem, try cutting those treats out completely.
  • Be sure that your chickens are spending at least part of each day outside. They need Vitamin D for the calcium they eat to be absorbed properly, so a run with a solid roof really isn't optimal for chickens.  They should be in the sunlight for the majority of the day if possible.

  • Add some herbs and other greens rich in calcium to their diet. Some good choices include: alfalfa, burdock root, chamomile, chickweed, clover, dandelion greens, horsetail, lambs quarter, mustard greens, nettle, parsley, peppermint, raspberry leaf, rose hips and watercress.
  • In severe cases, some liquid calcium can be added to your flock's water as an added calcium boost.

The Problem with Soft Shelled Eggs

Soft-shelled eggs aren't a problem merely because your hens aren't laying eggs that you can eat, but because a hen laying soft-shelled eggs may more easily become egg bound or suffer peritonitis. 

Two conditions you definitely want to avoid if at all possible. So taking steps to harden those eggshells is imperative! 

Take a Peek at my 'Rubber" Duck Egg  Video

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For more egg oddities, read HERE.

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