why don't eggs sold in supermarkets hatch into chicks?

As others have said the eggs have not been fertilized.

Secondly, a fertilized egg must be incubated at about 93 days for 21 days to produce a chick, so even if the eggs had been fertilized the refrigeration prevents the development of a chick.

NB It is not because of pasteurization. The eggs are not pasteurized, at least, not in the U.S. -- there are now pasteurized eggs on the market but that is, I believe, a single brand out of all the brands of egg sold (and it's only recently been introduced to the market).

The rooster must be present for an egg to be fertilized. Most eggs that you buy at the supermarket are from hens that are raised without a rooster being present. Roosters are not necessary at egg farms where eggs are produced for consumption. Eggs for incubation are grown at special farms called breeder farms where roosters are present with the hens.

Because they aren't fertilized. They keep the Roosters out of the hen house.

Plus they're too cold. The hen has to sit on them.

BTW, Common Sense: Pasteurization is when you heat stuff up to kill bacteria. I think you got the milk and egg departments mixed up. Funny though.

They have not been fertilized. A fertilized egg has a red speck in the yolk. But in general, eggs sold at stores should not have been fertilized.

They aren't fertilized. Eggs have to be fertilized by a male before they can become chicks.

Because they are mainly battery eggs ,they have not been selected for hatching, only eating.This is sad but true,There is a possibility of the free range eggs hatching if they are kept in the right conditions /heat levels etc.The best way to hatch eggs is to have your own hens /free rangers that are healthy and happy.All those hens and chicks that are murdered by the breeders are a sad case of Human Greed. The breeding laws are being changed in 2012.Its to late everyone should campaign for this to come into immediate effect.We must rescue these creatures that live in such terrible conditions.

It's possible...

http://news.bbc.co.uk/1/hi/england/suffolk/6643407...

the eggs are not fertilized and it is too cold

They are not fertilized eggs.

99.9% of hens at the ranch have never been close to a rooster.

then the eggs are refrigerated,,, killing any development.