Chickens eggs come in all kinds of colours – white, brown, pale creamy colour. We have
some with spots. We even have blue ones. But no, even in Scotland they don’t get tartan
eggs. So what makes the colour? And do we get brown
eggs from brown chooks, and white eggs from white chooks?
No matter what the colour of the egg, it’s really just a white egg with a coating on
the outside – either a smooth coating or a coating with a few spots and speckles in
it. Or like this one, it looks like even brown on one end but there’s spots and speckles
on the other end. If you look inside a white egg, you can see
that it’s white all the way through. If you look inside a brown egg, you can see very
clearly that actually it’s white inside. The brown egg is just a white egg with a brown
coating on the outside. It takes about 26 hours for a hen to make
an egg and most of that time is actually spent making the shell. And only during the last
couple of hours is the brown coating put on the outside. The brown coating comes from
a substance called protoporphyrin, which is related to a substance called haemoglobin.
Haemoglobin is of course the substance that makes our red cells red.
Whatever colour eggs a hen lays, she lays pretty much the same colour all the year round
– that’s her colour egg, although it does tend to get a bit paler as the season wears
on. You can see this in the colour of the eggs that my two hylines lay. My two hylines
are both the same age – about two years old, and to start with they both laid eggs
that were this dark brown colour. But as time went on, the eggs got paler and paler, until
now, one of my hens, Goodness, lays eggs that are just about this colour. Shirley, however,
took a break over the last winter, and didn’t lay any eggs at all for about a couple of
months. And when she came back on the lay again, now she’s laying these dark eggs
again. During the time that she took a break from egg laying, she refilled her paint pot,
and now she’s got plenty of brown colour to put on her eggs again.
So Shirley and Goodness are brown hens and they lay brown eggs. And Gillette and Remy
are white shavers, white hens and they lay white eggs. And Margy, my buff laced Wyandotte,
is kind of a creamy coloured hen and she lays creamy coloured eggs.
And as it happens, mylavender Araucana lays blue eggs.
So do brown eggs come from brown hens and white eggs from white hens? Well, no, not exactly. But you can get an idea of the colour of the eggs
that a hen lays by looking at the colour of her earlobes.
Did you even know that a hen has earlobes? They are those little bits skin on the sides
of the chickens head. For most of the breeds that we know well,
a hen that lays white eggs will have white earlobes. The white colour comes from a substance
called purine that makes their earlobes white. And a hen that lays brown eggs has earlobes
that are red. The red comes from the colour of the blood showing through – kind of like
the inside of our mouths are red or pink. This association between the colour of the
earlobes and the colour of the eggs doesn’t always work, because there is actually no
genetic link between the genes for earlobe colour and the genes for egg shell colour.
Silkies have blue earlobes, but they are not the ones that lay blue eggs, silkies just
lay a white egg. So what about those blue eggs? Fascinatingly,
unlike the brown colour that’s just applied to the outside of the egg, if you look inside
a blue egg, you’ll see that the blue colour goes all the way through. The blue colour
is actually incorporated into the egg shell when the egg shell is being made. The blue
colour comes a from a pigment called oocyanin, or oocyanin, I’m not really sure how to
pronounce it. That’s a substance related to biliverdin. You might not be familiar with
the name biliverdin, but I bet you are familiar with it – it’s the pigment that makes
bruises look green or blue. The hen adds oocynanin all the way throughout
the production of the egg shell, and so the blue egg is blue all the way through.
If a hen that lays blue eggs also puts a brown coating over it, the brown on top of the blue
makes it look green. It’s fun getting different coloured eggs
in my nest box every day. That’s one of the reasons I have different kinds of chickens
in my garden.