[RansomStark]

I've seen it: It's gruesome, but I'm not sure if in-ovo sexed roosters have a better end, or if its just more palatable to watch.

Eggs take 21 days to hatch, in-ovo techniques work at 9 - 15 day post laying, depending on the technique used. Couldn't find any details on how developed the embryo is at 15 days, but 2/3's done feels pretty far along.

[rtkwe]

They develop very rapidly in their last couple days so the 15 day embryo is a long way from the 21 day hatchling: https://www.nature.com/articles/s41598-024-72004-y/figures/2