For many people, the process of egg-laying can seem a little complicated. Where do eggs come from and if they have such a hard shell, how do they get fertilized? Those are just a couple of questions that many people have.
Well, you don’t need to wonder anymore! Here we’ll tell you all there is to know about how do chickens lay eggs. We’ll also see how they get fertilized, and answer any FAQs you may have. Read on to find out more!
How To Chickens Lay Eggs
Chickens lay eggs in a four-part process. The first is the creation of the egg yolk, then the white albumen is formed before a shell develops on the egg. Finally, a bloom is added, and the egg is laid. Here we’ll go through those four stages while answering some questions you’ll probably have.
1. The Yolk
Deep into their ovary, a hen develops a large number of yolks at any given time. And yes, this is the same yellow yolk that you still see when cracking the egg. It’s from this yolk that a baby chick would develop if the egg was fertilized and incubated.
Once a yolk has matured, then it will be passed through to the chicken’s oviduct. From here, it will have a continuous journey until it’s eventually laid. At this point, there are no egg whites surrounding the egg and no shell.
It’s at this point that a chicken egg would become fertilized. If they mate, a rooster’s sperm will travel from her vent all the way up her oviduct before eventually getting to the point where a yolk is released.
Sperm can survive in the oviduct for around four to five days after mating. Whether sperm is present or not, after around half an hour, the yolk will move down the oviduct where the next stage of the process begins.
2. The Albumen
As it moves further down the oviduct, the egg yolk will start to get its first layers of thick egg whites. This is called the albumen and is secreted from the oviduct onto the egg. This will gradually build up over the course of around three hours.
The intended purpose of the albumen is to provide food for the growing chick until it’s ready to hatch out of the egg. This albumen is a protein that supports the rapid development of a chick but is also what makes eggs so nutritious for humans.
As the albumen is secreted, the eggs slowly spin inside the oviduct. This helps to develop its formation and shape, getting it ready for its shell casing.
3. The Shell
Now we have all of the contents of an egg, how is the shell formed? Well before that, a membrane is added to the egg to protect its insides and allow for a shell to form on the outside. The process of membrane formation takes around an hour.
After this, the egg is primed for the shell which is formed by calcium carbonate. This is an inorganic salt that hens carry in their bloodstream. Humans have calcium in their blood too, except we use it for bone growth and repair!
These calcium minerals are of course tiny, but when millions of them are added to an egg, a hard shell can begin to develop. Around two grams of calcium carbonate will be added to the membrane over the course of about 20 hours.
It’s an incredible feat of human nature, especially considering that some hens can produce nearly one egg every day. If you have a prolific egg layer, this is why they need a lot of calcium added to your diet.
4. The Bloom and Laying
The last part of the process is the bloom. This is a protective outer layer that the hen adds to the eggs, consisting mainly of proteins. The reason for this coating is to protect the inside of the egg from any bacteria on the outside of the shell.
This is especially important as chickens only have one hole for mating, egg laying, pooping, and urinating. Therefore, the egg needs to pass through the cloaca, which is the same opening that their poop passes through.
It’s this protective bloom layer that means freshly laid eggs don’t need to be refrigerated. A light bloom is barely perceptible to humans as it’s an incredibly thin clear layer. However, if you touch an egg immediately after being hatched, it may feel a bit sticky as the bloom has yet to dry.
Does Fertilization Matter?
One of the biggest questions that people have is does fertilization matter in the process of egg-laying. The answer is absolutely not. Just as a human woman will release an egg once per month whether sperm is present or not, a hen will release her yolk even if sperm isn’t present.
Due to this, you don’t need a rooster if you want hens to lay eggs. Even without the potential for mating, a hen will lay eggs at the same rate as they always do. The only reason to have a rooster is for the protection of your flock or if you want to breed chickens.
Fertilization also doesn’t matter when it comes to us humans eating eggs. To turn into chicks, a fertilized egg will need to be incubated and kept at high temperatures for 21 days straight. Without that, no chick will form.
Due to this, a fertilized egg, when kept at room temperature or below, will not develop into an embryo. As a consumer, you’ll have no idea whether you’re eating a fertilized egg or not. While fertilization isn’t important, there are a few factors that can affect egg production.
The main one is if a hen goes broody and wants to sit on her eggs in order to hatch them. If she does, she will go into motherhood mode and won’t lay another egg until she stops being broody which, if uninterrupted, will last for 21 days. However, many prolific egg layers have their broodiness bred out of them.
There are other factors that can affect egg laying too. Some hens reduce or stop egg production in the winter, and they can stop making eggs if they become unwell. Also, as a hen gets older, her egg production will gradually slow down before eventually stopping.
What Happens Next?
What happens to an egg once it is laid if you don’t collect them? The answer to this depends on whether or not you have a broody hen. If you do, then she will sit in her nest for 21 days, barely leaving for food or water.
But what happens to unhatched eggs, and what happens if your hen isn’t broody? In this case, your hen will simply see her job as being done and abandon the nest. Sadly, she can do this before all of her chicks have hatched if some are a little late to the party!
Another slightly disturbing thing that can happen is that a hen (or other hens) may eat the eggs. While this feels wrong, many animals do it in nature as eggs are a great source of protein.
Of course, if you want to eat the eggs then you should collect them soon after they have been laid and store them at room temperature or in the fridge for longer-term storage.
If you want to breed your chickens, you can go down the natural route and let your hen lay on them. However, you’ll have much higher hatch rates if you collect the eggs and place them in an incubator.
How Often Do Chickens Lay Eggs?
Now you know how chickens lay eggs, how often do they do it? Well, the answer to this question can vary wildly. As mentioned above, some chickens are able to make nearly one egg per day, which is incredible given the process they need to go through.
Chickens that can make over 300 eggs per year are almost always hybrids. This means they have been bred from two parents of different breeds to make a perfect layer. Prolific egg-laying hybrids include the ISA Brown and the Golden Comet.
Heritage breeds that aren’t hybrids usually have a lower level of production, with the good layers giving you around 200 eggs per year or around four per week. While these are the production levels of the best layers, some other breeds are on the other end of the spectrum.
Some chickens may only produce one egg per week, and can also stop laying in the colder months. So as you can see, there is a huge range here, which means you need to choose your chickens carefully if you want a great egg layer.
Hopefully, now you know all about the wonderful process by which chickens lay eggs. It’s an impressive series of stages that remains a mystery to many people. From the ovary to the cloaca, a small yolk turns to a hard-shelled egg in around 24 hours.