You may remember that we started 31 eggs in our new incubator almost two weeks ago. From the very beginning the big question has been: how many are fertile?
The process that's used to figure this out is called candling. It involves holding the egg to a bright light in a dark room, to get a view of the contents. There are lots of websites with photos showing eggs at different stages of development, but there's a big difference between reading a book or looking at some pictures and figuring it out yourself with a flashlight in one hand and an egg in the other.
Kim and I gave it a try the other day. I was in charge of the record keeping, light switch switching and second opinion proffering, while Kim did the candling. What we were looking for was the air sac at the bigger end of the egg. In the photo you can see it on the left. That sac will get bigger as the embryo continues to develop. We were also looking for veining (visible at the top in the photo) and a dark mass that could be the embryo.
The air sac turned out to be a really easy thing to spot. Quite a few of the eggs had visible veining, and in some of those the embryo was very distinct. It was thrilling, actually. We were especially happy to find that most of the Australorp eggs were fertile - there was a time, after all, when we thought that Hector might be a gay, mute rooster. But he's doing his job - good Hector!
By the time we were finished we had decided that six of the eggs weren't fertile, so we took them out of the incubator and disposed of them - gently, since they were likely to be smelly if broken. So we're down to 25 eggs. There are still things that can go wrong before the hatch date of March 4 or 5, but we're excited to have made it this far.
Image from here.