As a backyard chicken-keeper, it is not uncommon to find irregular eggs. Do not worry unnecessarily about the occasional strange-looking egg; take a picture of it, discuss it at the water cooler next day and get a good chuckle out of it. They happen, and the vast majority of the time they do not indicate any cause for concern.
Before we get to all the pretty, funky and bizarre egg pictures, it’s important to understand how a hen’s reproductive system is supposed to work when firing on all cylinders.
Here's the deal with a hen's reproductive system: a female chick's ovary contains all of the ova it will ever have when it's hatched. The ovary begins to convert ova to egg yolks when she is mature. With the right lighting conditions exists, hormones stimulate ova to develop into yolks. Yolks are released from the ovary into the oviduct when they reach the right size and travel down the oviduct to acquire their whites, membranes, color (if any) and shell. An egg requires approximately 25 hours to complete the addition of the
egg white, the shell membranes, and the shell. Soon after an egg is laid, the process starts again.
A hen's reproductive system consists of an ovary and oviduct (a long tube with several parts that have different jobs).1
The following is an actual hen's reproductive tract.1 I have labeled the functions that occur at different junctures along the way. If fertilization is to occur, it happens in the infundibulum, which is the area immediately to the right of the ovary (the black line is running through it in this photo). The infundibulum is a muscle that essentially engulfs the ovum (yolk) when it is released. The sperm waits in the infundibulum and has a narrow, 15-18 minute window of opportunity in which to fertilze the ova there.
FERTILE AND INFERTILE EGGS
INFERTILE EGGS: Infertile eggs are ones that have not been inseminated by a rooster, and as such, will never hatch chicks. All eggs contain a concentration of cells on the yolk called the blastodisk, which is identified by its light color and irregular shape. When fertilized, the blastodisk becomes known as a blastoderm.
FERTILE EGGS: When an egg is fertilized by a rooster, the blastodisk becomes known as the blastoderm, which is the first stage of embryo development. The blastoderm is also known as the germinal disc. When incubated under particular temperatures and humidity levels for 21 days, these cells will develop into a chick. The blastoderm is characterized by its bullseye appearance of regular, concentric circles.
EGG IRREGULARITIES
DOUBLE YOLKS:Commonly occur in new layers when the yolk release is mistimed and two yolks travel down the oviduct together. Some hens are genetically predisposed to laying double-yolked eggs.
Can a double yolked egg hatch? The short answer is: very rarely. While extraordinarily uncommon, miraculously it can happen, watch twins hatch here!
NO YOLK: Also known as rooster eggs, wind eggs, dwarf eggs, rooster eggs or fart eggs (I just report the news, folks, I don't invent it.). Commonly occur with new layers when reproductive system isn’t quite synchronized yet.
Eggs without yolks can occur in older layers when a piece of tissue from the reproductive tract frees itself, fooling the hen’s reproductive glands into treating it like a yolk, creating an egg out of it. The little piece of tissue is visible in this photo:
NO SHELL OR THIN SHELL: I call soft-shelled eggs ‘rubber eggs” as the membrane is soft and pliable. These eggs are commonly produced by new layers, caused by either an immature shell gland or a glitch in the reproductive system when the
shell was not properly added in the shell gland. Can be caused by stress or poor nutrition. To find them occasionally is no cause for concern, to find them regularly can indicate a calcium, phosphorous or vitamin D deficiency.
ODD SHELL SHAPE OR TEXTURE: (Includes too large, too small, flat-sided, 'body-checked' eggs) I
affectionately refer to these as 'mutant eggs.'
In new layers, an immature shell gland can cause odd shell shape and is most often of no concern. In senior layers, oddly shaped eggs can result from stress or, if they are a regular occurrence, a defective shell gland. Misshapen eggs can also be caused by infectious bronchitis or egg drop syndrome, both of which are cause for alarm.
Shells with wrinkles or ‘checks’ in the shell are known as ‘body check’ eggs. These eggs have been damaged while in the shell gland from stress or pressure put upon them. These eggs are repaired in the shell gland, resulting in checks/wrinkles. Some of the eggs that follow fall into several of these categories.
ROUGH-SHELLED OR PIMPLED : Egg shells can have different textures causes by a range of things from excess calcium intake (pimpled eggs) to double-ovulation, disease, defective shell gland or rapid changes in lighting conditions (sandpaper eggs). As long as these types of eggs are found infrequently, there is no cause for concern.
FLAT-SIDED: Can occur in new layers due to stress or disease. The egg is kept too long in the shell gland, resulting in a flat side with wrinkles. Can also occur when a mis-timed, second egg proceeds down the oviduct, bumping into and resting alongside the first egg.
UNUSUALLY LARGE: Eggs of unusually large size ordinarily contain double yolks, and the hen's reproductive system accommodates for the anomaly by working overtime to generate these monstrosities.
The average extra-large egg weighs 64 grams and a jumbo egg weighs 71 grams. The two largest eggs I've ever had were 90 and 95 grams.
ABOUT SHELL COLORING: All egg shells start out as white eggs. Colored eggs have their pigment added to the shell a little later in the formation process.
BROWN EGGSHELLS contain the pigment protoporphyrin, ( a by-product of hemoglobin) which is found only on the surface of the shell. Brown pigment is applied in formation of the last layer of the egg, the bloom or cuticle. The brown pigment can be rubbed off easily and does not color the inside of the shell.
BLUE AND GREEN EGGSHELLS are produced by the pigment oocyanin, (a by-product of bile formation). The color is applied early in the shell's formation and penetrates the entire shell. The blue coloring cannot be rubbed off.
White egg shells have no pigment at all. Uneven, striped, spotted or speckled shell coloring results from the uneven distribution of pigment as the egg passes through the oviduct.
EGG WITHIN AN EGG: This extraordinarily rare situation occurs when an egg that is almost ready to be laid reverses engines into the reproductive tract, meeting up with another egg-in-progress. It gets another layer of white/albumen and a new layer of shell before being laid. The cause is not known.
BLOOD SPOT: When a little blood from the ovary joins the yolk down the reproductive tract, a blood spot will be seen in the egg. This usually occurs in older hens that have a genetic predisposition to them or that have a vitamin A deficiency. While it can occur randomly in any egg, less than one percent of all eggs will contain a blood spot.
The preceding information is provided as a general guideline to understanding some egg irregularities and some of the more common causes of them. It is not intended as an exhaustive review of the subject. If you have some concern that your hen may be ill or consistently produces irregular eggs, you should consult an avian vet or perform in-depth research based upon your individual circumstances.
1Anatomical illustrations and photo reproduced for educational purposes, courtesy of Jacquie Jacob, Tony Pescatore and Austin Cantor, University of Kentucky College of Agriculture. Copyright 2011. Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, M. Scott Smith, Director, Land Grant Programs, University of Kentucky College of Agriculture, Lexington,and Kentucky State University, Frankfort. Copyright 2011 for materials developed by University of Kentucky Cooperative Extension. This publication may be reproduced in portions or its entirety for educational and nonprofit purposes only. Permitted users shall give credit to the author(s)
and include this copyright notice. Publications are also available on the World Wide Web at www.ca.uky.edu. Issued 02-2011
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I agree completely, Sara! My pleasure.
Thanks Pam. :)
Donna, congratulations, your name has been drawn as the winner of a Happy Hen Treats prize package! Please email me with your mailing address: Kathy@The-Chicken-Chick.com
I got my first chickens in July and first eggs in December but there's always the issue of decreased daylight and its impact on egg-laying. You may want to read a little more about it to see if supplemental lighting is something you want to do or not. http://www.the-chicken-chick.com/2011/09/supplemental-light-in-coop-why-how.html
My pleasure, thank you!
I'm sure they do, Alex. It's pretty good incentive to get to work. LOL Good luck!
Thank you Britny. :)
Thanks Janet and good luck!
Thanks for stopping by tonight Charity!
Yay! Ive seen this page before but didnt know this was where to comment! Lots of great info, Ive learned a LOT here!! Thanks! Charity
Great article...as always! :) Thanks for the info! brit868@yahoo.com
this is a very good article -- i would love to win the treats
My chickens haven't started laying yet, but I can't wait!! They absolutely love themselves some meal worms.
Loved the article, will re-post! Thanks for the tips!
They'll get there before you know it! Thank you. :)
Thank you Mary. It certainly doesn't cover all the freakish egg possibilities, but it does cover the most common. I hope your peeps enjoy it too. :)
Thank you Lisa!
My pleasure, Sharon. Thank you for stopping by to read it!
This is so interesting. Thank you for posting!
This is such an amazing blog, so informative and fun!!! thank you!
This is the perfect, perfect post for all those egg questions...and the photos sure make it easier to understand. I will for sure be passing this post on to my peeps.
My pleasure Diane, thanks for stopping in to read it!
Thank you Karen, I appreciate that.
Thank you Patty!
Thanks Cheri! Me too. ☺
Thanks! It'll be in a nest box before you know it!
We got them in april, they are 6 weeks old, I am assuming the eggs are coming in november,lol. We can't wait for them! We are enjoying our little ladies so much!
I cannot WAIT until mine start laying....I just gotta hang in there...LOVE THE INFO!!!
Love the egg info!!! Love Grit...... Cheri @ Angel Hill Farm
Thank you Marilyn!
Hi Alex! Thank you. ☺
Kimberley, did you just call me cheep? LOL! Thanks for stopping over to read my blog post on Grit Magazine's website!
Did you just get them this month, Amy? Collecting your first egg is very exciting but the truth is, it never gets old!
Thank you Dolly and you're in!
Good for you, Linda! Be sure to share pictures on Facebook with us when they do!
Hi Karen and thank you for stopping by to read along today!
Thanks Dolly, you got it!
Flavia, did they tell you that? :o
Kara, I've never had an egg within an egg either. Crazy, isn't it?
Thanks Alison and you're entered!
You bet Michele, thank you!
My pleasure, Shantel!
You'll always remember your first egg, Felicia. Keep that camera handy!
Welcome to chicken-keeping Susan. It's a BLAST!
Funny, Sandy. I hope it helps to shed some light on a few things for them! :)
I'm sure they do, Deborah. What's not to love about Happy Hen Treats? :)
Good luck Alicia!
Thank you Buffy! Will do. Good luck!
My pleasure, Leslie. Thank you!
Thanks so much, Elizabeth. I appreciate that. :) Great tip on preserving "windys." ;)
Thank you Renee!
Interesting reading.
Very informative and interesting article!
Thanks Stacy! If you ever get twin embryos, let me know!
Thanks so much, Debbie! It's nice to have you joining me in my chicken adventures!
You jinxed her!
Excellent Article, very informative and great photos. Thanks for sharing..
So eggciting, Robin! Did you take a picture?
I got a double yolker today !!
I had a hen that consistently laid a double-yolk, until i bragged about it. No more doubles.
I loved reading all about how an egg is formed and all the other articles you posted. This is my second year to have my four hens and I am loving them so much. I sell the extra eggs to purchase feed for them and my customer's love the fresh eggs. I follow you on facebook and also your blog and would love to have those treats for my hens.....they are so spoiled!!!! Thanks for the giveaway.....Debbie........dellerd@msn.com
Thanks for this article! I had no idea what an actual production line egg laying is...fascinating.
What a great post this has answered many of my chicken" I wonder " question about Eggs..I've always wondered if a double yoke egg could actually develop two chicks!! Amazing and very informative..:>
Great article, thanks ! We've had a few of these odd eggs so far... I always refer back to your site when I have a question ! Please enter me in the treat giveaway ! Thanks ! rlb_13@hotmail.com
Great info, Chicken Chick, as always you have done your homework, making sure to share accurate information. That's just one of the many reasons I am a one of your fans!!...I have several "windy's" ("windy" my granny's name for the yolk-less eggs) that I have collected from my hens over the years...I wash them, which removes the bloom, and just lay them up in a sunny window to let them "dry up"...then add them to my collection...lol...Plese enter my name in the giveaway. Thanks!!!
Thank you for such a wealth of information! And I love the pictures of the eggs...this makes me excited for my girls to get old enough to lay! :)
I love the beauty and variety of eggs. I think the biggest joy of having chickens is having a variety of eggs. Thank you for the useful information!
Great article! Thanks for putting it all together-so educational! Please enter me in the Happy Hen (chicken crack) giveaway! :-)
Would love to win some Happy hen treats for our ladies :)
We wanna win our hennies some Happy hen treats please! They literally eat them out of our hands!
I have to show some of my friends this blog because they don't understand how you get a chick out of an egg and all that fertility stuff! Lol! Thanks: )
It's an anatomy lesson and science all rolled into one! Great info for newbies like me!
I can't wait for my first egg. So exciting.
I can’t wait to get our first egg! So much to learn, thanks for the article!
Thanks for all the information! Very informative!
Always love reading your blog...would love to be entered to win some Mealworms....my girls (and boys) LOVE them....its been a while since I've gotten any so some of the "newbies" will get a first taste of heaven lol
I've had just about all of these, except the egg within an egg. I think it's interesting how different all the eggs can be!
very interesting and my hens feel like they need some treats, so please enter us in the giveaway !
Love all of the information in this article. Please enter me in your giveaway. I thank you!
Great article, very informative!
Thanks for this info, new to raising chickens so will be some good info when my hens do start to lay, which should be soon!
Love this informational post. Please enter me in your giveaway also and thanks!
My chickens will be laying eggs in November, this was very informative!
I recently had a really long egg with a double yolk, and because my chickens are young we get funky eggs all the time. Thanks, you cheep
Hi Chicken Chick. Very informative.
Thanks Makenna, great timing! :)
Thank you Marilyn!
Be sure to take a photo of it, Julia! And if you're feeling ambitious, blow it out so you can save it forever (the shell anyway!). DIY instructions are on my blog here: http://www.the-chicken-chick.com/2011/10/egg-blowing-101-and-how-to-decorate.html
Great post! I can't wait to get my first egg!
I loved this posting..
Great blog post Kathy. Good information-especially because I just got my first fart egg today from one of my new layers! Now I am not the worried about it.
Thanks so much, Robin!
Thank you, Melissa. ☺
Thank you Amanda!
Thank you, Marie! Happy to share. :)
Thank you, Audrey. The good news is, you don't have to remember everything, you can always refer back to my blog posts to refresh your recollection. Keep your camera handy for that first egg!
Knowing just a fraction of the things that can go wrong in the process of making an egg, I find it remarkable that 'normal' eggs are produced with such regularity.
Thank you Gavin! It's so nice to have one of my long-time BYC peeps along for the chicken-keeping journey with me. :)
Thanks Holly! Give my best to Cheep-Cheep! ;)
Bernadette, you DID?! I hope you took a photo of it! That particular weird egg totally fascinates me. I've never had one.
Stick with me, Pupp, I'll bring you up to speed with your lovely wife. ;)
Thank you, Donna!
This was such an information piece--I will stop worrying about those occasional egg 'oddities' I can't explain. Your photography is amazing--very clear to follow along with your explanations and insight. Thank you SO much.
Very informative. We have chickens (lots of them) and my wife knows a lot. I just pick up the information here and there. Picked up a lot today :)
Very interesting, I actually had an egg within an egg a few months ago, it was the weirdest thing ever! Thanks for the info!
Awesome page! A lot of great information!
Love all your posts, both here and on fb...... Gavin.
It's always good to be reminded of the possibilities our girls leave for us to find .. And to know why these oddities probably happened.
I think I learn something new every time I read your blogs/post/articles! Thank you for taking time to share your chicken knowledge with us! I hope I retain everything I've learned when my ladies start laying eggs in the next month or 2!!
Fascinating article! I have studied a lot about hens and eggs but I sure learned some new things here. You have some great photos too! Thanks :)
Thank you, Heather. :)
Thanks Christine!
Thanks Elisha! Nice to have you following along!
My pleasure Esther. Keep your camera handy because it won't be long before yours are laying too!
Your blog is always so informative. I have really enjoyed reading this post!
thanks for the post! so informative and interesting, and thanks to grit for sharing your blog! Melissa~
I love your blog! So informative . Thanks you!
Now I know what to expect when my chickies start laying! Thanks for a great overview :-)
Great information... thank you so very much! Love your blog too.... always enjoy learning more about my chickens :) Thanks!!!!!!!!
Thank you for posting this article! Very informative and it's always great when there are pictures to go along with descriptions, makes identification so much easier!
Thank you Kathy! I love your blog. What a wonderful article. I love how you described the whole egg process, the beautiful pictures, and the illustrated pictures. I'm going to share it with all of my friends. Have a blessed day.
Congratulations on your new baby chicks Nicole!
That's great to hear, Nikki. Thanks for following my blog, it's nice to have you along for the adventures!
Thank you Joann!
love the pics, you always have some great info, love it "Got Eggs!!!" have a wonderful day.
I had turned to this article when our hen had put out a pimpled egg. Super informative and I made sure to bookmark it so I can keep coming back whenever I have a question!
Very informative. My pet hen, Penny, just hatched out four chicks this week. I, as well as they are learning something new everyday. Thanks for this post on the egg cycle.