Do we eat fertilized or unfertilized eggs?

Do we eat fertilized or unfertilized eggs? 

Whatever they may come with, eggs have long been a staple in more kitchens than one around the globe. But how much do we actually know about the eggs we eat every day?

Some may see it as a trivial question, but the difference between whether the eggs we eat can produce a live chick or not has deeper implications than many people realize. Those who already know this know that fertilized eggs were mostly about village chickens or free-range hens.

In fact, the process of a hen's egg being fertilized is a bit more complex than assuming that any egg laid by any hen can eventually hatch into a chick.

A Misunderstanding of the Fertility Cycle

While it is assumed by many that a hen lays eggs that can successfully hatch into chicks as long as a rooster has mated with the hen. However, that's a naive assumption.

It goes beyond the act of mating. When they do mate with a rooster, however, hens do not lay fertilized eggs (as many other birds do), but only fertilized eggs, unless a rooster is around. As there are no affection or romantic bonds between the rooster and hen, the relationship will be a matter of convenience. The rooster's main purpose in life is to mate in order to keep the flock going.

Mating involves the rooster jumping on the hen's back and reproducing. The sperm that he releases while doing so does not directly result in fertilization of the egg. Instead, the sperm waits in a specialized area near the hen's uterus.

This is where things get interesting the hen does not always accept the sperm of every rooster. If she finds the rooster unappealing, the hen will expel the sperm just after mating. This is instinctual behavior, because hens are choosy about their mate.

Eggs are fertlized in not occurring instantly

Even if the hen is accepting of the rooster, the egg produced in the immediate aftermath of his coital passion may go unfertilized. It took time for the egg to go through various stages of development. It takes about 25 hours for an egg to form inside the hen's body.

Consequently, eggs that are laid on the first or second day after mating will be less likely to be fertilized. The third day after mating is a more likely time for fertilization. That timing is critical and happens to be what decides if the eggs that a hen lays can become a chick.

Sperm Storage and Longevity

The most interesting aspect of hens and how they lay fertilized eggs is the way they store sperm. The sperm from different roosters is stored in specialized cells in hen's reproductive tracts. That means even mating with a rooster one time could result in her laying fertilized eggs for the next 10 to 14 days.

This is a remarkable characteristic of the hen's reproductive system, enabling her to produce fertilized eggs while having little interaction with the rooster. Since the rooster may no longer be present in the environment, hens are able to keep laying eggs that can still be fertilized.

Egg Production and the Role of Infertility

Hens can hold onto rooster sperm for sometime and must be fertilized to lay eggs However, that doesn't mean that every chicken is fertile. Some roosters may not produce viable sperm, which means that any hens that mate with them will not lay fertilized eggs either.

It is important to understand this aspect of infertility, which shows how not every egg a hen lays is capable of becoming a chick. A rooster's fertility is key to whether hens in a specific flock will produce an egg that can become a chick.

This idea is somewhat akin to the reproductive cycles of humans, interestingly enough. As not all human males can reproduce, not all roosters have fertile sperm. Particularly, this similarity highlights the complexity of reproduction in both humans and animals.