Not a dot, not a bullseye...?

[DonyaQuick]

So I know that a dot or otherwise amorphous solid blob means unfertilized, and a clear bullseye means fertilized. I've seen many examples of both from my flock. But, for lack of a better way to put it, what does the appearance of the Greek letter Theta mean? I've seen it more than once from the same hen recently. I have never seen a clear bullseye from her eggs though. I've also turned the yolks over when I've found these theta shapes in case it was an anomaly other than "the" dot but no, that's the only thing present that could be it.

 

[sourland]

New one for me.

 

[FunClucks]

Have you tried incubating this hen's eggs? I'd guess it meant fertile, but it would be interesting to see how many of her eggs made it through to hatching and whether they had any abnormalities in the chicks. I've never seen this before, and am curious.

 

[BigBlueHen53]

Twins?

 

[DonyaQuick]

Have you tried incubating this hen's eggs?

Earlier this year yes, all duds sadly. Never saw any hint of embrio and did check post-incubation by cracking them open; just runny yellow yolk. However, those dud eggs pre-dated the appearance of these theta shapes. I really, really want to hatch from this hen, but she's 9lbs with an 8lbs roo who is having a somewhat hard time getting the important parts lined up because of how big she is. The theta shapes did show up after I saw what looked like more successful mating attempts.

When I tried incubating her eggs before, I wasn't seeing a clear bullseye but was seeing more like an O with a dot touching the edge of the ring. I've got other eggs incubating right now so will have to wait a while to test hers again if it's worth doing. I am worried though whether I've stumbled into some kind of early development lethal trait with this pair's eggs though. I know there are some that hit very early in development, I just don't know what they look like when cracked open.

 

[my21chickens]

thats interesting! i almost wonder if its "twins"

 

[DonyaQuick]

An egg from today from the theta-shape hen is now back to more what I'd been seeing from her before the thetas started. You can see some of the theta shape is still there but it's more wonky than that. I had been interpreting this as infertile but it is quite strange. I don't know if it makes any difference, but this hen is a giant cochin cross (I don't know the other half of the cross). The rooster is also a cochin cross with an unknown.

Meanwhile for comparison, these other 3 eggs from different hens who are with the same rooster.

Infertile from a purebred cochin hen who does not mate with the roo.

Fertile from another pure cochin hen; I am incubating two of these eggs right now. Both eggs in the incubator are showing good development with one week left to go.

And then I got a pacman today from 4th pure cochin hen that has been giving me a roughly 50/50 mix of clear fertile and infertile (tried to incubate 2 of hers and they were duds...). That's the first occurrence of a weird shape from someone other than my cochin cross hen. Maybe it's something to do with the roo???

It seems like I have two main possibilities:

• Something about the blastodisc is just mucked up, rendering it unable to develop even if fertilized. This would be an issue from the hen.
• I have one of the fast-acting lethal traits lurking in one or more individuals. This could be from either parent or both...

 

[DonyaQuick]

Forgot to mention something in my last post: I did look into the twin possibility after it was mentioned here. Seems like that is only likely in the event of a double-yolk. While I have seen a couple double-yolkers from other hens, none in this flock have done it. There is also apparently an extremely rare documented situation of two chicks developing from the same yolk, but it seems they do develop to a greater degree when that occurs even if they don't survive to hatch. But getting a sequence of several of those thetas in a row goes against the extreme rarity for that case. So I don't think twins is what's going on with the weird blastodiscs or blastoderms.