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Double Yolk Eggs: Causes, Safety and Other Egg Laying Anomalies

Double Yolk Eggs

The ‘egg factory’ situated in the hen is an intricate mechanism that usually functions exceedingly well for the first couple of years before gradually slowing down in the mature hen.

Occasionally there are hiccups in the ‘factory’, and it can produce double yolk eggs and many other egg abnormalities.

The odds of a double-yolk egg are around 1 in 1000.

First, we will do a quick review of the hens’ reproductive tract to remind ourselves of the anatomy involved and to marvel at how it produces an egg daily – usually without a hitch!

Then we will look at egg-laying anomalies such as double yolks, wind eggs, and no-shell eggs.

Hen’s Egg Laying Anatomy

It seems simplistic to describe the reproductive tract as a tube, but that is basically what it looks like.

Although born with two ovaries, the right shrivels, leaving only the left ovary to produce eggs over the hen’s lifetime. The ovary is packed full of ‘egg seeds’ (yolks) – more than enough for the hen’s laying period.

The egg grows within the ovary and, when ready, slips down into the first part of the tube called the infundibulum – it looks a bit like a trumpet.

The journey continues down the tube with varying amounts of time spent in special areas that add things like the chalazae (which holds the yolk in place) and, of course, the shell, which is applied in the uterus.

Once the shell is applied, the egg continues the short distance to the cloaca where it first sees the light of day when the hen lays the egg.

All this happens in a period of around twenty-five to twenty-seven hours.

Another yolk will be released from the ovary between thirty to seventy minutes after laying that egg.

‘Hiccups’ can occur at any point in the process, and some hens are more prone to problems than others.

Let’s look at one of the ‘best’ hiccups that can occur: the double yolker!

Double Yolk Eggs

Double yolks are fairly uncommon.

Around one in one thousand eggs will be a double yolk.

Triple yolks are exceedingly rare, but not unknown!

Double Yolk Egg

What happens is that a yolk is released and then another is released within a couple of hours.

These two yolks get encased in one shell.

Needless to say, this is a large egg that can cause problems like egg binding.

Fortunately, most hens seem to lay these monster eggs without mishaps.

The issue can be hereditary, but it is most common in production pullets just coming into lay, and occasionally older layers coming to the end of their cycle.

The younger pullets coming into lay suffer from hormone change and imbalance, which can cause the double yolk phenomenon.

Once they have settled into their routine laying pattern, double yolks should disappear and replace regular eggs.

If you were to buy your eggs from the supermarket here in the US, you would never see a double yolk egg – they are considered ‘imperfections’ by the industry.

In the UK, it is possible to find them in the supermarket.

If you were wondering it is possible to hatch out a double yolk egg, the answer is usually not, although it has happened.

If they do hatch, one chick usually succumbs since oxygen inside the shell is limited, and the stronger chick will survive.

There are rare instances of both chicks hatching, but no follow-up information on how they thrive.

Now that we’ve covered double yolkers let’s look closely at other egg anomalies.

Another way to prevent early double yolks from young hens is to “not push the issue.”

Meaning, don’t do anything to rush them into laying eggs, like adding a ceramic egg or overfeeding, thinking you are promoting new egg production.

Let their egg factories mature naturally, and enjoy the eggs when your girls are ready to give them to you.

Other Egg Defects

Lash Eggs

Lash eggs are not eggs…not wholly, at least.

Lash eggs are egg-shaped puss balls filled with other elements that may include egg particles.

These cheese-like egg-shaped gobs are formed within the reproductive tract of a hen that is ill.

Typically, a severe infection (either viral or bacterial) in the hen’s oviduct causes inflammation (Salpingitis).

If you see a lash egg, you must immediately save your hen.

It’s best to consult a veterinarian so the cause can be diagnosed and treated accordingly.

The infection that’s causing the lash eggs can be treated with antibiotics or surgery, depending upon the cause of the infection and the severity.

Sometimes, you may need to treat your entire flock, especially when the problem is contagious.

Lash eggs are pretty yucky, but keep an eye out for them and act quickly. You may save your entire flock.

Egg within an Egg

Imagine you crack open your egg to reveal…another egg! These are fairly rare events, fortunately.

No one quite knows why this happens – the completed egg suddenly changes direction and reverses back to the uterus, receiving an albumin coating plus another shell.

Occasionally, the reversed egg will bump into the next egg on the ‘conveyor belt,’ and another shell will be laid over both eggs!

Needless to say, the egg will be large, so the hen is not to be envied trying to lay that egg.

Although strange, the egg within is safe to eat.

Wind or ‘Fart’ Eggs

These are also known as fairy or witch eggs because of their size.

Tiny Eggs

In times gone by they would have been known as rooster eggs which were an evil manifestations.

People believed these eggs were laid by the rooster, and if the egg was allowed to hatch, the creature issuing from it was called a cockatrice.

A cockatrice could turn people to stone if they looked upon it, so the egg had to be thrown over the roof of the house without touching the house to prevent the birth of such a creature!

In actuality a wind egg is usually produced by young pullets coming into lay and having hormonal adjustments. They can have a teeny yolk, but many are yolkless.

Older hens can also lay fart eggs – usually if they have suffered some disturbance in their routine (new flock mates, change of feed etc).

These eggs are harmless and normal service will be resumed as soon as the hen pulls it all together!

Bumpy Shells

Bumpy, irregularly surfaced, or gritty surfaced shells that feel like sandpaper are caused by uneven distribution of calcium across the shell.

There can be a few causes of this harmless appearance, the incidence being higher in hens that lay early in their lives.

  • Defective shell gland – not much can be done to correct this, it is an internal problem of the hen although it may sort itself out over time in new layers.
  • Water shortage – can occur in summer when the drinkers run dry, or more commonly in winter when the drinkers freeze over limiting access to water.
  • Sudden lighting changes – any change in the lighting for the hens needs to be done gradually.
  • Disease – Infectious Bronchitis or Infectious Larngo-Tracheitis can cause this too. Although the virus causes primarily respiratory problems, it can cause infections in the reproductive tract also.

These eggs are fine to eat – if you suspect infection in your hens, err on the side of caution and toss them.

Soft Shells and No Shells

The shell in these eggs can be super thin, leading to a parchment look to the shell, or the egg is laid with only the outer membrane and no shell at all!
Egg Without Shell
Younger hens can produce them while they are coming into regular lay. It should settle down when her hormones are balanced out.

Older hens, especially good production layers are more prone to soft or shell-less eggs. The cause is not really known.

However, several factors can influence the problem:

  • Hot days – hens tend to reduce food intake when it’s hot thereby reducing the amount of calcium they take in. The problem usually resolves when cooler weather arrives.
  • Poor diet – a diet lacking calcium, vitamin D and/or protein will increase the likelihood of shell problems. Always feed a fully balanced diet to your hens.
  • Old age – happens to us all and things don’t work as they should! No known cure.
  • Obesity – corpulent hens do not lay as well as their more svelte sisters and suffer from more egg laying problems also.
  • Calcium absorption problem – a genetic problem with no known cure at this time. The calcium that a hen eats cannot be absorbed by her body leading to egg problems and bone trouble also.
  • Inflammation of the oviduct – also known as salpingitis. This is a very serious problem caused by a viral or bacterial infection. The only effective treatment is antibiotics, and some birds may respond well to the antibiotics, others will succumb to the infection. These affected hens sometimes lay what is known as a ‘lash’ egg. It is not an egg but an encased ball of pus and tissue that have passed through the oviduct.

Blood and Meat Spots

Blood spots occur inside the shell. When you crack an egg the yolk can be lightly blood tinged.

This is nothing to panic about.

A small blood vessel around the yolk burst and leaked out a minute amount of blood. This may not be attractive, but the egg is fine to eat. I use them in baking all the time.

Meat spots are brown and usually very tiny.

It is a particle of the hen’s reproductive tract which has detached and become incorporated in the egg as it passes by.

Again, these are safe to eat as long as it is cooked.

Double Yolk Eggs: Summary

The hen’s reproductive system is in constant motion – from releasing the yolk to building and laying the egg.

The cycle is repeated daily, so occasionally, there is a malfunction.

We have discussed several different ‘oddities’ in eggs today, especially double yolk eggs.

Although some of the more unusual eggs can be caused by disease, that is usually the exception rather than the norm.

As hens generally live longer than their ancestors, some problems associated with ‘old age and extended laying years are poorly researched.

Traditionally old hens went into the pot as soon as production dropped.

This is still true for ‘industrial’ hens, but our backyard ladies are living well into their dotage now.

If you are concerned about the frequency of odd occurrences in your flock, do a mental checklist to try to eliminate some possible causes.

Was the weather very hot over the last few days?

Were the hens deprived of water because the water froze in the drinker?

Has there been a stressful event for them?

Did I change their food?

How young/old are they?

If you can rule out all of the environmental factors that might contribute to a problem, then it’s time to start looking carefully at the hens.

Is there sneezing or coughing among them?

Does any particular hen look unwell?

Can you pinpoint the one who lays the oddities?

If you can find the hen who lays the problem egg, check her for any signs of illness or disease.

If you are concerned about her health, you can isolate her for a few days and see what happens.

If you suspect something like salpingitis or infectious bronchitis, you should take her to the vet for a check-over.

The vast majority of the oddities we have talked about are not unusual and can occur at any time, especially if your hens are stressed.

The chances of her having a serious problem are small and uncommon, although infection and genetic issues can arise.

So, the next time you get an ‘oddity’, you can use this article to help you understand what’s going on!

Let us know in the comments below about any egg oddities you’ve experienced…

Read Egg Bound Chicken: All You Need To Know

29 thoughts on “Double Yolk Eggs: Causes, Safety and Other Egg Laying Anomalies

    1. I have found that when my hens go broody, there are always a couple of others that ‘get sympathetic’ and stop laying too! Are you able to separate the broodies from the main flock? Also check for secret stashes.

  1. We have a Leghorn that will lay jumbo eggs every third lay. My husband and I were flabbergasted! They are indeed double Yolkers and largest weighed 97 grams. The eggs are delicious and we feel it’s a treat to get one, but it’s a wonder how our Leghorn passed such a jumbo egg!!

  2. My chicks are about a year and a half old and during their time since they started laying, I have retrieved a “fart” egg, a double yolk, a bumpy egg and a shell-less egg. They are free range on our 10 acres and all 3 chickens seem very healthy, and eat a good diet of laying feed, some scratch, all sorts of fruits and veggies and mealworms – and of course, fresh water daily. Their FAVORITE treat is blueberries. Always seems so strange when anything out of the ordinary is found, but as long as they seem happy, healthy and alert, I won’t freak out. They don’t seem stressed at all and enjoy their daily routines – making the rounds ALL around the property. Not sure who is laying what, but the entire neighborhood knows when they’ve laid! 🙂

  3. We have had a small number (6/8) hens over the years. At present we have six, – 2 Loman browns, 2 Scottish blue bells, and 2 white leghorns, all been laying for 4 months, all was well.
    However about 6 weeks ago the leghorns started laying eggs with very very pale yolks, just off white why? All hens have same food are freerange and are a wee bit flighty. What might be the cause.

    1. Have you recently changed their feed George? The color of the yolk is almost entirely made up from their diet…

  4. FYI – I have an isa brown that regularly lays eggs weighing over 100g and quite often they are double yolkers. She is not any bigger than the other Isa brown I have.

  5. I have 48 hens, and this year alone I’ve gotten 14 double yolkers, incl the friends I’ve given a few eggs to. An octogenarian friend got his first ever!

  6. Thank you for an excellent timely article. My two, a BS*xL and a BPR are laying daily. They are 1.5 yrs old. Last week the temperature went dramatically up and I got a monster egg. BSL laid it and her eggs usually weigh 65-70 grams, this one was 120 grams. I was worried but nothing seems to have changed and she keeps laying normally.

  7. I have two isa browns my first ever, the larger one seems like she is laying a reasonable size egg but her friend who is smaller doesn’t seem to be laying. What could be the cause? plus we are getting double yokers a lot they are small yolks though. they are both about 24 weeks.

    1. Hi Jenny,
      They are both so young I wouldn’t worry too much. Give them until 30 weeks old to get into the swing of things!

      1. Hi Lisa,
        The rooster won’t be causing them not to lay eggs. What are you feeding them and do they have access to 12+ hours of daylight?

  8. I have 4 Rhode Island Reds and 5 Black Barred. I have 1 that quite often lays a shell less egg, and another that lays a very large egg. Also many of the eggs have very watery whites. They free range in a large yard and I feed them layer feed, calcium supplement and appropriate table scraps. They are in their 2nd year and seem healthy and content. Any thoughts about the watery whites?

  9. We have 4 hens. All less than a year old and they just recently started laying. One of the hens lays a double yolk egg every day.

  10. We live in the US & we just got a carton of eggs last week for our local family dollar. So far EVERY single egg has been a double Yolker. Only 3 left in the carton, we’ll see if all of them end up being. So much for 1 & 1,000 lol

    1. That happened to me last year – 8 out of 12 was a double! I’ve always heard it was lucky to find one, but no lottery wins for me. Good eating, though.:)

    2. Brookshires extra large eggs, found 3 double yolk. Scrambled them for the dog. I know they are okay to eat but will pass.

  11. I have been buying locally produced eggs from a cage free farm…no antibiotics, but not organic. The past three dozens have had double yolks in all of them. I love them, but I am just concerned if they are all safe to eat. They are the tastiest eggs and I love the extra yolk.

  12. We just bought two dozen eggs at our local coop and ALL two dozen were double yolkers! Whatvwould cause this??

  13. Double yolk eggs are sold in the US! I just finished using up a dozen jumbo size eggs that had 5 double yolkers. This is quite common around Easter. I buy the jumbos all the time and have had as many as 8 double yolkers in a dozen. I’m sure this is because they are feeding the hens extra hormones to ensure an adequate supply of eggs for the Easter bunny.

  14. Hi my 4 month old White Leghorn laid a double egg yolk egg this morning, I’m just wondering is that ok because she’s still young

  15. Planning to add housing for a flock? Follow these important considerations before building or buying a chicken coop model for your birds.

  16. once i got a double yolk! me and my great aunt we were baking and we found it so we just used one less egg.

  17. Flocks of hens tend to be all of roughly the same age, in this case, ones that have only just started laying.

    1. Have a flock of 9 Sapphire Gems….”Stormy” has been laying daily for a week now and she’s just shy of 4 months old! Her eggs are small (biggest 2 inches) but 3 of them had double yolks! I’d never seen double yolks in such tiny eggs! They were quite a treat to eat, absolutely delicious!

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