eli5 how are chickens or chicks all hatched at once?


So chickens, they lay 1 maybe 2 eggs a day. Every day. But then they hatch out 10 or so babies all pretty much at once. Or at least in the same day. So how does that timer work? Do they just go into over drive and lay them all at once? How come the first egg laid doesn’t hatch long before the last egg? How does that genetic timer work so they are all “born” around the same time?

In: 4

I’m sure wild chickens do have chick’s hatching all the time and not synced up.

In the hatchery, they put all the eggs in the incubator at the same time and that’s how they get so many to hatch all at once.

A hen doesn’t start really sitting on her clutch until she’s laid (or stolen!) a nest full of eggs. Once she’s satisfied with the amount of future offspring she will sit on them for 23.5 hours a day, leaving only to eat and dust bathe, for 21 days, when they will hatch if they were fertilized. The development of the embryo starts when she warms them up, not when the egg is laid.

It’s consistent heat that makes the baby chick in the egg start to develop. The hen lays a couple of eggs first before it commits to sitting on the eggs until the chicks hatch. Once the hen starts sitting on the eggs to apply consistent heat, it seldom leaves the eggs or the eggs will go cold and the developing baby chick inside will die.

Now, you can collect and hatch the eggs yourself using any heat source but you need to be careful — the temperature must not be too high or too low. It must be the same as the hen’s when it’s sitting on the eggs. Too low and the baby chicks will not start developing, too high and it will “cook” the eggs. The eggs too must not be more than a week old or they may not develop at all, worse, you’ll end up with stinky eggs. The fresher the eggs, the higher the chance of hatching.

Store-bought eggs will not probably hatch as they may be unfertilized. Hens without the help of roosters will lay unfertilized eggs.