Don't count your chickens before they hatch.

Mimi is only interested in a playful snack

Eleven out of twelve fertile Bresse Gauloise eggs hatched but the fertility was only 67%. So I can't sell any yet L'll have to check the fertility again in a week or two.

When people buy hatching eggs they have high expectations. Often unrealistic expectations.

There are just so many factors that can affect how many chicks you get from a given number of eggs. This is especially the case  when the eggs are sent by post.  Rough handling of the package, big changes in temperature and changes in atmospheric pressure when they go by air can have serious effects on fertility and hatching. So I have to ensure that the eggs are as near 100% fertile when they leave here in polystyrene boxes by express mail.