^{Written by Senior Hatchery Specialist, Martin Barten}

Customers and participants on our training courses often ask me: “What is the most important aspect of incubation?” Usually, I turn the question around and ask them what they think it is. Temperature is often mentioned, as well as relative humidity and turning. Indeed, a turning failure in early incubation can seriously impede hatching.

In my mind, however, the question should be answered differently, or even asked differently, and should be: “What is the most important period of incubation?” For me, this is clearly the first ten days. On day ten of incubation, the embryo is more or less complete and the body parts are clearly recognizable as a mini chick. All the embryo has to do from this point on is grow. Of course, the embryos must not overheat and they must receive sufficient oxygen and lose sufficient weight to achieve an air cell that can easily be pipped, but the real challenge is to get every embryo as uniformly as possible to day ten and in such a way that it is well developed and strong. After all, whatever you do wrong in this period cannot be corrected later! Getting the first ten days right is therefore the foundation for a good and uniform hatch and a narrow hatch window. Mother Nature knows this too: a broody hen is much more attentive to her nest at the start of incubation than in the last few days, when she leaves the nest more regularly for food and water.

So, how to get the first ten days right? This starts with loading the setter with eggs that are as similar as...