Why Do They Die At The End? The Chicks Were Fully-Formed

WHY DO THEY DIE AT THE END?

This is the most frequently asked question. And it's heartbreaking having fully formed chicks make it all the way to the end and then fail to make it out. Why do they die at the end? The first thing to understand is that the time of death has little to do with the causes of the death.

As the embryo's oxygen requirements increase towards the end, while the oxygenation is still via the veins just beneath the shell, the pores in the shell become unable to keep up with the supply. CO2 builds up and the embryo begins convulsing, almost dies, and the convulsions cause head jerks, and the egg tooth tears the inner membrane into the air cell. This gives it immediate access to a rush of oxygen which initiates pulmonary breathing. But then, that air tank starts to deplete and again the pores in the shell aren't able to replace the oxygen being used by the now "born" hatchling, so for a second time, CO2 builds up and again the head jerks, the convulsions, a second near death experience, and the egg tooth pips a hole to the outside air.

Many, many fail at one of those two choke-points, and it can be for the whole raft of earlier causes, whether incubation settings, dietary deficiencies, malpositions, genetics, or an accident of nature.