Miniature Crested Duck Hatching?

[Horse Rider12]

Hello,
I am planning on breeding my two crested females soon, but I heard that the chicks can have severe problems inside the egg, and even die. Can anyone give me info on this, any at all, to do with crested breeding? Is it a different outcome if I breed a crested with a call duck?
Thank you!

 

[Tim]

Crests are a mutation causes a lethal allele combination. Two crested ducks mated together cause quarter of the embryos to die in the shell before hatching.

The offspring of a crested-crested mating will have some ducks without crests as well.

If you mate a crested duck with crest-less drake, some of the offspring will still have crests and this is the preferred way to breed crested birds since you will avoid the lethal allele combination that causes the dead-in-shell embryos.

I hope this helps.

Tim