What causes a fully formed chicken not to hatch in an incubator?
Often the mortality rate of near hatch chicks is because of low humidity or high temperatures. Once the chick is fully formed inside the shell, moisture keeps it lubricated for movement within the shell case. The chick needs to move in order to complete its peeping or breaking of the shell and dry shell/low humidity is often the culprit. The first few hole made by the egg tooth allow air inside the shell but also increases the release of moisture so the humidity in the incubator should always be at least 65% or better for good hatch rates.
