Earlier this week, we thought we had a broody hen already occupying our most popular nest box in a largest flock. Splotchy had set up camp and was sending out her broody sounding warnings anytime another hen came around. She is the only EasterEgger hen in the flock and lays a nice blue egg, and she is also the hen who sneaked hatching three fuzzballs late last summer. She’s relatively young – just coming into lay last spring, so we thought she’s just going to be one of those broody-every-time-you-blink kind of hens. Since we are in no short supply of chickens right now and anything she might hatch would be a real barnyard mix, we were not real interested in letting her continue.
Shortly after the discovery, we could hear a very loud egg song coming from the coop. Mama Mo mentioned to Papa Mo that Splotchy was already broody for this season, to which he inquired if that was her making all the noise (he rarely hears the egg song since he’s typically left for work when the hens get moving for the day). We discussed since she was broody she shouldn’t be laying and went about our work repairing another chicken hutch.
Later in the afternoon, Mama Mo noticed she was out of the nest box and used that opportunity to collect any eggs before Splotchy had the chance to hatch anything. Surprise! There was a gigantic blue egg in the box! No wonder she was camped out in there for so long and making so much noise! Not surprisingly, it was a double-yolk egg that most likely resulted mainly from upset to the coop arrangement for that folk.
This mostly young flock was overwintered in a storage-building-turned-barn, and we are trying to finish it out as a permanent coop. Unfortunately, many of the young pullets have already started laying for the first time, and we are scrambling (no pun intended) to get nest boxes and such prepared for them, resulting in lots of confusion and disruption to regular laying right now.
Now, we tell this story to explain about double-yolk eggs. Many people think they are cool and some even brag that their hen lays double-yolk eggs all the time. We feel that, not only from the hen’s perspective (have you heard them yelling when laying those giant eggs??) but from a healthy chicken perspective, it could possibly not be such a good thing. And here is why: it means the hen’s reproductive tract could be stressed &/or injured.
An egg is produced when ovum/yolk is released into the oviduct to go through the cycle of forming the egg that is laid. About an hour+/- after an egg is laid, another mature yolk is released to start its cycle which takes approximately 25 hours to complete. The entire egg production cycle is a finely tuned process that can occasionally experience a “glitch”. If there is a glitch in the cycle, multiple things can result, such as more than one yolk being released causing a double-yolk egg to develop. This particular glitch in the egg production cycle is typically the result of hormonal change or imbalance as young hens are beginning to lay eggs or as an older hen’s typical egg production cycle slows down. It can also be hereditary, and some cultures in other countries breed for this trait.
The double-yolk phenomenon is typically harmless and produces perfectly edible eggs, but it does usually mean an extra-large egg which increases the risk of egg binding, vent prolapse (part of the oviduct protrudes from the vent) , or peritonitis (infection caused by yolks falling out of the reproductive tract). All of these can lead to death through injury &/or infection.
If your hen consistently produces abnormally large double-yolk eggs, she should be watched closely for any complications that could result from stressing or injuring the reproductive tract. Some hens that produce double-yolk eggs do so with normal size eggs (we suspect these are the hereditary cases) and are at far less risk of developing any complications.
Here are multiple articles discussing double-yolk eggs, egg production, and other associated problems:
- The Happy Chicken Coop: Double Yolk Eggs: Causes, Safety and Other Egg Laying Anomalies, June 14, 2017
- Better Hens & Gardens: What Causes Double Yolks?
- Fresh Eggs Daily: What Causes a Double-Yolk Chicken Egg?, Sept 20, 2013
- Countryside Daily: What Causes Double Yolk Eggs and Other Odd Eggs?, April 4, 2017
- How Stuff Works: Why are people superstitious about double-yolked eggs?
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