How Many Eggs is a Chicken Born With?

Many people know that a woman is born with a finite number of eggs when she is born, but does this same principle apply to chickens?

A chicken is born with tens of thousands of ova, or potential eggs, when she is born. As soon as the chicken hatches from her egg, no new ova or yolks will be produced; whatever number of ova she has at that point is the most she will ever have.  Most of these undeveloped yolks will never develop into eggs.

Keep reading to find out how the number of eggs a chicken is born with translates to number of eggs laid.

It Starts While in the Egg

All the nutrients needed to provide for the growth of an embryo are inside the egg once it’s laid. These nutrients include:

• Vitamin A. This vitamin is essential for a hen, especially if she will be laying fertile eggs. Vitamin A aids in good hatchability and increases the capacity of chicks to live and continue to develop once hatched.
• Vitamin D and Calcium. Vitamin D is needed for the assimilation of calcium. Calcium is a major ingredient in egg shells and when there is a deficiency in calcium, egg shells become weak and thin. Developing embryos take calcium from the shell for development of their bones. A deficiency in Vitamin D will lead to an increase in embryo deaths and rickets in chicks that hatch.
• Vitamin E. Vitamin E improves fertility in hens and roosters, while also improving the ability of fertilized eggs to hatch.
• Riboflavin. Also called Vitamin B2, riboflavin is necessary for preventing embryonic death and birth defects in chicks.

While all these nutrients aide in the development of embryos into a chick, they are also very healthy for humans which is why eggs are so nutritious. When a hen is fed a balanced diet and supplemented with vitamins and minerals as needed, she will pass along those nutrients through her eggs.

Since chickens are prey animals, they have a reproductive design that increase their odds of survival.  One of those traits is developing their offspring external to their body in the form of eggs that remain in a nest and can be hatched either by the hen who laid the eggs, another hen, or another bird entirely, like a duck.  

While an embryo is developing inside the egg, she will grow tens of thousands of ova, or yolks. Once the chick begins to hatch out of the shell, the creation of the ova will cease and the number of yolks at that moment be the most the chicken will ever have.

The Most Productive Years of Egg Laying

A chicken will lay the highest rate of eggs in the first 2 years of her life. After 2 years, a hen’s egg production starts to gradually decline.

Even though a young female chicken, or pullet, is born with tens of thousands of potential eggs, most of these yolks will never develop to the point of ovulation.

A chicken’s yolks are stored in her left ovary and range in size of a pinhead to nearly full size yolks. As a pullet begins to lay eggs, the yolks start developing one at a time until they are fully developed and ready be released into the oviduct. This post has a section devoted to explaining the process of a yolk being released and how it becomes an egg.

Smaller breed pullets start laying eggs about 18 to 22 weeks of age, with larger breeds taking as long as 24 to 26 weeks of age. Two of my Barred Plymouth Rocks started laying at exactly 24 weeks, with the remaining chickens laying over the course of the next 2 weeks.

In general, the following breeds will start laying at these age intervals and lay the indicated number of eggs per year:

Egg production is dependent on many factors, which is why the ranges for each breed can vary so much. Examples of factors that can affect egg production include:

• Hot weather
• Issues with nesting boxes
• Poor nutrition

Egg Laying Slows Down with Age

Fertility in chickens starts to decline after about two years, at which point hens will lay fewer eggs than they did before (some punny people like to refer to this as “henopause”).

If an older hen is inseminated, she can still lay fertile eggs that can hatch; however, the rate of viable embryos will decline. Older hens are more likely to have embryos not make it past the first few days of incubation or for those that do, the chicks have an increased chance of failing to emerge from the shell.

This is why most breeders won’t use hens older than two years of age.

Hens that are kept as pets can lay eggs for up to 12 years. Albeit, the number of eggs will be dramatically decreased from their pullet days, with maybe one egg laid per week.

When factory chickens have a decline in egg production at around 2 years, they are considered to be spent and will be culled (or selectively killed) and a new batch of chickens will go through the same process.

From the tens of thousands of yolks that a chicken is born with, only a few hundred of them will ever develop into eggs. By taking care of your flock, you will be able to increase their egg production and raise happy and healthy chickens.