How do eggs get their colour?

[Lucylou]

Just out of interest I've often wondered what determines the colour of an egg (shell ) & in particular how it is that one of my chooks lays eggs that are different colours, sometimes they're light pinky/beige others varying shades to quite brown.
When I had more chooks I thought the lighter ones were laid by a different hen but now I only have 3, I can easily identify whose laid this one (my Campine lays white, my big black bird lays large brown, so that only leaves one other laying the 3rd!)
Sometimes these eggs are slightly speckled at one end.

Any ideas knowledgeable ones?

 

[dinosaw]

I can't give a really detailed explanation Lucylou but basically the colour comes from pigments deposited on the shell during formation, the pigment itself is dependent on the genetics of the chicken which is why different breeds lay different colours.

 

[Lucylou]

Oh, interesting. So my chook who lays these assorted colours is probably a hybrid then & not the purebred she was sold as !! lol ! Her genetics are obviously a bit mixed up!

 

[chrismahon]

As far as I know Lucylou they all do that. The white speckles are usual and we get them on and off with lots of our birds. The only breed I know that doesn't lay white eggs with colour added as a coat is a Cream Legbar that lays blue eggs the same colour all through (and which are the same colour as its lobes). But there was a discussion a while back and it sounds like the green/blue Cream Legbar egg layer adds a green coating over their blue egg? I wouldn't say your hen is a hybrid at all Lucylou, just a bit varied as many of ours are.