Cracked open one of our eggs this morning and found this. Ewww...
Is it a fertilized egg? We have only just discovered that one of our bantams is a roo, but don't think is old enough or big enough to breed with our big girls....at least yet.
No, it's just an egg laying mistake, the kind that don't make it to the shelf in the grocery store. It is harmless to you and probably not an indication of what this bird will lay in the future.
Sometimes, a blood vessel ruptures in a hen's oviduct or a piece of tissue gets lodged in the egg, and causes this. Its just a fluke ocurrence that happens every so often. It may be unappetizing, but doesn't mean that your hen is sick.
You won't see blood in a fertile egg until it has been incubated for several days. There's only one subtle difference between a fertile fresh egg and an infertile fresh egg. A fertile egg will have a tiny white spot that forms a bull's-eye on the yolk (kind of like a doughnut). Infertile eggs will have a white spot too, but it will be poorly formed, without a hole in the middle.
That is why when using eggs from my own flock I always break them one at a time into a clean coffee cup before adding that egg to the other ingredients.