[northfifeduckling]

I found a fairly large grey lump (pea sized but flat)  in the white of a duck egg....pretty ugly and I do hope it doesn't happen to anyone else eating our eggs (might put them off for life). I don't think it's embryonic as that would be in the yolk I thought?
Can anyone share ideas or wisdom? Never found one in a hen's egg btw....

[doganjo]

The white is where the embryo grows, the yolk is it's food supply, so I think it may have started developing.

[northfifeduckling]

ooops, thanks, Annie. After all these years and I always thought that the spot in the yolk would turn into the embryo 

[doganjo]

Wiki says - The yolk is a part of an egg (or just of the egg cell in non-egg-laying animals) that feeds the developing embryo in animals.
But I just found this so we may both be right - seems the yolk is fertilised by the sperm then the white is wrapped round it and the whole thing spirals until it is laid so they are twisted together, then the embryo develops and feeds off the yolk

The Formation of an Egg:

The Yolk: The chicken egg starts as an egg yolk inside a hen. A yolk (called an oocyte at this point) is produced by the hen's ovary in a process called ovulation.
Fertilization: The yolk is released into the oviduct (a long, spiraling tube in the hen's reproductive system), where it can be fertilized internally (inside the hen) by a sperm.

The Egg White (albumin): The yolk continues down the oviduct (whether or not it is fertilized) and is covered with a membrane (called the vitelline membrane), structural fibers, and layers of albumin (the egg white). This part of the oviduct is called the magnus.

The Chalazae: As the egg goes down through the oviduct, it is continually rotating within the spiraling tube. This movement twists the structural fibers (called the chalazae), which form rope-like strands that anchor the yolk in the thick egg white. There are two chalazae anchoring each yolk, on opposite ends of the egg.

The Eggshell: The eggshell is deposited around the egg in the lower part of the oviduct of the hen, just before it is laid. The shell is made of calcite, a crystalline form of calcium carbonate.

This entire trip through the oviduct takes about one day.

Growth of the Embryo: The fertilized blastodisc (now called the blastoderm) grows and becomes the embryo. As the embryo grows, its primary food source is the yolk. Waste products (like urea) collect in a sack called the allantois. The exchange of oxygen and carbon dioxide gas occurs through the eggshell; the chorion lines the inside surface of the egg and is connected to the blood vessels of the embryo.

[northfifeduckling]

After a few month I had another one....This egg definitely has been laid yesterday, so it had not been kicking around a warm place or anything like that. I'm utterly puzzled what this could be!
And I seriously hope that my friends never find any of these when they open an egg...
When you look at the pictures, folks, do any ideas spring to mind?

[lord flynn]

is it the duck equivalent of a meat spot in chicken eggs? they're made up of oviduct lining-its nothing to do with embryo development.

http://poultrykeeper.com/egg-problems/meat-spots-in-eggs

[northfifeduckling]

Thanks, for this, l f. Sounds just like it 

[lord flynn]

I have one hen that does it, one of the older ones. Its not very nice but I just fish it out and eat it (the egg!), nothing bad's happened yet. They get those and blood spots commercially as well, so I'm told, they are candled out though.

[northfifeduckling]

I do the same but I can imagine folks that get disgusted by grey stuff looking like a small flat brain in their egg...I have some quite elderly ducks from the first ever batch (8 or so years ago...) so it makes perfect sense.

[lord flynn]

can you candle duck eggs? might be worth trying if you're selling them.

[northfifeduckling]

the white ones, yes although usually it's bigger shadows  . I'll try, good idea