Earlier I wrote about having the opportunity to raise some pullets for a customer (“My First Chicken Customer”). This would be my first experience using an incubator, but after thoroughly studying the instructions and setting it up in a suitable spot, I didn’t think much could go wrong. My Little Giant Still-Air Incubator® holds about 40 eggs, and I was only setting ten, so I arranged them in a single row around the heating element. After candling the eggs a couple of times (something I’m not very good at yet), I concluded that four of them were infertile. Well — I got three of them right, but when I broke the fourth one, unfortunately it did seem to have an embryo, though perhaps it had died. All the others did definitely seem viable, except for one that I wasn’t sure about.
All seemed to go well for a couple of weeks; then one day I noticed that the temperature sensor, which is supposed to rest on top of the eggs, had slipped off. I didn’t know how long it had been like that, since I hadn’t opened the incubator all day; resting it on a single row of eggs was a little tricky, so it could have been gradually dislodged by the motion of the automatic egg turner. Anyway, I replaced it on the eggs, and to my horror the temperature reading began to climb until it reached over 105 degrees! The correct temperature is 99.5, which is what the incubator was set for. Apparently it gets a lower reading where there aren’t any eggs.
So I removed the cover and let it cool as quickly as possible. Now, you would think it might have occurred to me to arrange some eggs in a square, where the temperature sensor would more likely stay put. But I guess I didn’t have my thinking cap on. Would you believe the same thing happened again a few days later? And this time I hadn’t thought to add water for a day or two, and I think the incubator may also have dried out.
After 22 days no eggs were hatching, so I unplugged the incubator and took the six remaining eggs out to the compost, breaking each one to see what was in it. One did have a nearly-developed chick that had died. But, surprisingly, five of them seemed to have nothing but a yolk. Now, I had retained these in the incubator because, when candling, I saw a large dark area in them, though I couldn’t make out the embryo or network of blood vessels that you’re supposed to see, whereas the ones that I got rid of allowed the light to pass through evenly.
At first I assumed that the five eggs had been infertile, which would make eight infertile out of ten(!) I wondered if the age of the parents was to blame — eight to nine months at the time the eggs were collected. I had read that very young birds can have low fertility, but I’m not sure how young is “very young.” Then I realized I had forgotten you’re supposed to tilt the eggs first one way then the other when you’re storing them, so that the embryos don’t become stuck. Apparently they need to be able to rotate freely in the egg while incubating. So maybe they were fertile after all, but just never developed.
The one (very) experienced chicken breeder I’ve consulted replied that he never tilted eggs until recently, but hadn’t had a problem. Then again, he’s never collected eggs from birds that young, but hatches them early enough so they’re 10 or 11 months old by start of the breeding season. I'll have to research this a bit, but I guess I'll need a more mature flock before I try this again. (And maybe more practice with the incubator!)