What Causes Double Yolk Eggs & Other Odd Eggs?

Egg Facts Help Determine if Odd Eggs are Just That or a Sign of Something Worse

double yolk eggs

As spring chicks start to grow up and lay eggs, odds are you may find a double yolk egg in your egg collecting basket. To be clear, double yolk eggs are just that. When you crack a single-shelled egg open, you won’t find a fully formed egg inside of an egg, instead, you’ll find two yolks inside.

It’s funny because so many of us live our lives buying eggs from the grocery store. There all the eggs are uniformly sized, perfectly colored and have no oddities. But, this is a distorted reality and not the way chickens really lay eggs. (Commercially, odd eggs are used in food where they can’t be seen such as baking and cake mixes.) In reality, there can be lots of odd eggs laid by a hen over the course of her lifetime. Most of them are edible and perfectly fine to eat. Think about it, hens can lay a thousand or more eggs in their productive years. The mathematical odds of something being perfect every time are low, if not impossible.

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So what causes a double yolk egg? To understand that, it’s necessary to review how a hen lays an egg. Hens are born with all the eggs they will ever be able to lay already inside them. (This is the same with female humans too.) The yolks are contained in the chicken’s left ovary, which is her only working ovary. Once the hen is of laying age, individual yolks will mature and be released into the oviduct. It takes a hen 26 hours or so to form and lay an egg. Then about an hour after laying, another mature yolk will be released and start going through the egg formation process.

Double yolk eggs or in rare cases, triple yolk eggs, are formed when the hen releases two or more yolks at once. They move through the reproductive tract and are encased by a single shell.

double-yolk-egg

Why do chickens lay double yolk eggs?

You may wonder how you know if your hen laid a double yolk egg. Most times those eggs will be much bigger than a standard size egg; double and even triple the size. Ouch! This isn’t always the case, though, as I’ve had hens lay double yolk eggs that looked exactly the same size as a standard egg. But that’s rare.

Double yolk eggs are more likely to happen as chickens begin their laying cycle. At that point, a hen’s body is starting to get into a rhythm, and as with any rhythm, it can be hard to pick up the beat every time. Double yolk eggs can also happen at the end of hen’s laying cycle as things are winding down causing that rhythm to be thrown off beat.

Double yolk eggs are not lash eggs, which are a sick chicken symptom and not really an egg at all. You may find that double yolk eggs can mimic chickens laying soft eggs. In reality, the same amount of calcium goes into a double yolk egg shell as goes into a standard size shell. So, you may find your double yolk egg shells a little softer than normal.

Soft eggs are not always a sign of sickness, although a hen regularly laying soft shelled eggs should be monitored as this can be a sign of infectious bronchitis and oviduct issues such as salpingitis. But, most likely a soft egg is caused because of warm weather or because your hen needs more calcium in her diet. For warm weather, just make sure your hens have adequate places to get out of the direct sunlight such as under trees, shrubs or decks and have plenty of accessible fresh water. For inadequate calcium, it’s a good idea to feed your chicken’s egg shells back to them. You can clean them and then crush them up into small pieces and offer them free choice in a bowl or treat container. You should always make sure to feed a well-balanced layer feed to your flock and you can add supplements such as herbs from your garden and Seabuck 7 to help with consistent egg laying.

Statistically speaking, double yolk eggs happen in about one in every thousand eggs. They are more common in hybrid and large breed chickens and can be hereditary. (In some countries, hens that lay double yolk eggs are prized and bred to lay them.) Although they are not a sign of illness, double yolk eggs can cause problems for the laying hen. Consistent laying of extra large eggs can lead to egg binding, where the chicken cannot pass the egg and it’s stuck inside or prolapse where part of the oviduct is sticking out of the chicken’s vent on the outside of her body.

Ultimately, a double yolk egg or other odd eggs, happen during the productive years of a laying hen and they’re nothing to worry about. We shouldn’t expect a hen to lay a perfect egg every time she lays. But, if you get a lot of odd eggs consistently from one hen or from many flock members then it may be a clue that something is wrong.

Have you found a double yolk egg, or even triple yolk egg, in your nest boxes? Let us know in the comments below.

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Comments
  • yes I get double yoke ,sometimes 3or4 in a row but goes in spells. The Gold Buff lays them .

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  • I get at least one double yolk egg in every dozen of white jumbo eggs i buy from Big Y supermarket…………………………..

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  • When you refer to soft shells do you mean thin shells or rubbery shells? I have had both kinds.

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  • One of my chickens is laying eggs the size of a marble, what’s up with that??

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  • The only double yolk that I have ever had was from my geese, not my hens.

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  • I have a flock of mostly barred rock hens that are just now starting to lay and I have got a couple of double yolk eggs. They were almost the size that the hens will end up laying as they mature.

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  • My saggitas are laying a lot of double yokers …. They are new layers. It’s a special treat !

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  • My Ameraucanas just started laying eggs at almost 5 months of age. I found 1 double-yolk egg one day, and another double-yolk egg the next day! I’m not sure who layed them, or if it was the same hen. Regardless, it was a nice surprise since I’ve never had Ameraucanas before 🙂

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  • I bought my eggs in a German grocery store. The entire dozen was double yoked. It kinda freaked me out.

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  • I have 23 new layers and have had many many double yolks, but even more fascinating is I just had one of my girls lay a fully formed egg INSIDE another fully formed egg! Two full shells, two yolks and two whites! The outside egg was 3″end to end and 6″ around. I have pictures but can’t upload them here. I do have them on my Facebook page for A Few Acres Farm.

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  • One of my hen laying double yoke eggs except one small sized softer egg on oneday

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  • I have a 5 yr old Americana that laid double yolks in every egg she laid, at least 3 every week her first year of laying. Year 2 and her fellow Americanas took off and did not lay. Year 3 and 4 she started laying again, double yolkers. Now in year 5, she sat in a nest for 4 months, laying no eggs. Had gotten a fertile egg from a friend thinking I could slip it under her and let her hatch it out.. and she left the nest! 2 months later she started laying again, but now single yolk jumbo eggs!

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  • I usually buy my eggs at a certain supermarket. I usually buy 3 dozen every other week, but lately I have gotten dozens with double yolks. Having been brought up on a farm, I am fully aware that not all eggs are double yolk. Do you suppose that the chicken farmers are giving steroids to chickens? Are they dangerous to be consumed in such large quantities? Please let me know. Thank you.

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  • We had a very strange egg. It was HUGE! We cracked it open, out came a egg yolk and egg white and a complete egg, shell and all. How often does this really happen. Got a video of us opening this egg, thank goodness.

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  • I had a hen hatch out twins one time. It took me a while to figure out how she had more chicks than eggs 🙂

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  • I got Plymouth barred Rock hens and lots are laying jumbo eggs, double yorkers and for their first month of laying their eggs were tiny and still double yolks in them. Was unbelievable that such a tiny egg could hold 2 yolks. Then a hen laid a huge jumbo and yup it was a triple yolkier

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  • every time I start a new batch of hens,you will first get pullet eggs then usually a double yoker or two before they get into a rhythm.

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  • We bought 2 Dozen cage free eggs from Costco. So far the first 11 have all been double yoke!

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  • Casey K.

    One of my Black Copper Marans lays 3.5oz double yolked eggs about every 2 weeks and she’ll lay them 3 or 4 days in a row sometimes.

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  • Recently I have purchased six brown colour, large size double yolk eggs from a local poultry product seller. This is very commonly found in my local market.

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  • Sherry S.

    I have a Red Sex Link hen that lays a triple about every two week. Many of the other times she will lay a double yolk. This has always been a rare find in my flocks in the past.

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  • I have had doubles here and there, also marble sized eggs and an egg with no yoke at all. chickens are entertaining!!

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  • Our backyard flock consists of (15) Heritage Rhode Island Red hens to (1) rooster. The flock is free range and feed all natural feed & wall water. I don’t know if this helps form double yolk eggs, but we also feed them vegitables & fruit. The hens lay double yolk eggs just about every month or so. Double yolk eggs are definitly larger in size. Our customers enjoy the random surprise of getting double yolkers and keep coming back for more. They comment that it bring back memories of the old days.

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  • One of my customers had a 4 yolk egg. How can I send you a picture of it?

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    • Steph M.

      Hi Ramona! We got your picture. Wow, that’s amazing. We are going to feature it in our next e-edition. Watch the site for that next week. ~Steph

      Reply
  • Yes! I have gotten a lot of double yolks (Bonus) through the years! No big deal, they are usually about the size of one and a half eggs, so you can tell them apart!

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