[nicky d]

Just a wee question,  if you had an Rhode Island Red x Cream Legbar what coloured egg do you think the hen would lay?     Nickyxx

[Sassy]

Usually it would be a blue egg as this gene is strongest but it doesn't work every time.

[nicky d]

Thanks sassy for that    nickyx

[cluckingnuts]

Khaki coloured.

[Sassy]

Khaki coloured.

Yes that's true. I have a Cotswold legbar (Idon't know the relationship, if any, with a cream legbar) and she lays a khaki coloured egg.

[themagicaltoad1]

I might be wrong about this but I'm sure I read somewhere that whatever the cock was would dictate the colour of the egg, so a cream legbar cock and a RIR hen would produce blue eggs, but if it was the other way round they would be brown.

[nicky d]

I might be wrong about this but I'm sure I read somewhere that whatever the cock was would dictate the colour of the egg, so a cream legbar cock and a RIR hen would produce blue eggs, but if it was the other way round they would be brown.

hmmm well i defintaley know that the cock is the rode island red and the hen the cream legbar   nickyx

[joyfull]

I also thought they took the egg colour from the cockerel (but often with a slight variance IE blue can often turn out green, putty or khaki

[cluckingnuts]

Blue (O) eggs are dominant to white (o+). Brown is a combination of protoporphyrines that lay a pigment on the eggs.

[jhub]

If blue is dominant could it not have a recessive gene for white or does it only work that way in humans?

[Casey76]

If only it was as simple as dominant and recessive 

You can have incomplete dominance (or partial penetration) also - but I don't think that applies to egg colour, that will depend on homozygocity / heterogenicity.

E.g. if you have a homozygous blue egg layer (O/O) mated to a homozygous white egg layer (o/o) you have two possible outcomes...

O/o and o/O (which is basically the same), and O being dominant to o(+) you will end up with pullets that all lay blue eggs (as they will all be heterozygous)... however, they may be paler blue eggs than homozygous layers... and that's where it starts to get complicated!.

If you have two heterozygous (O/o x O/o) layers ther are three outcomes...

O/O (blue eggs)
O/o or o/O (blue eggs)
o/o (white eggs)

The shell colour of both blue (and white) eggs goes all the way though... (the shells are blue on the inside too).  Brown eggs are really white eggs with varying depth of pigment layered on top of the white shell during the time in the oviduct.  If you have a blue egg layer crossed with a brown egg layer, you will end up with basically a blue egg with varying shades of brown layered on top, which gives varying colours of blue/green/khaki/putty.  These eggs (from the same hen) may change over the laying season - as an ordinary brown egg may change colour too.
 

[jhub]

Thanks Casey, so it is the same as eye colour in humans.
Jane