Why Do Fully Developed Chicks Die Right at the End?

Few things are more disappointing than opening an incubator to find fully developed chicks that never managed to hatch.

This is probably the most common question I'm asked:

"Why did they die right at the end?"

The first thing to understand is this:

The time of death often has very little to do with the cause of death.

In many cases, the chick's fate was determined much earlier during incubation. The final stages of hatching simply expose problems that have been developing for days, or even throughout the entire incubation period.

The Two Choke-Points

I think of the final stages of hatching as two critical choke-points.

A chick must successfully negotiate both if it is to hatch.

Choke-Point One – Internal Pip

As the embryo grows, its demand for oxygen increases dramatically.

Until this stage, oxygen reaches the embryo through blood vessels beneath the shell. Eventually, however, the shell can no longer supply oxygen fast enough for the embryo's increasing needs.

As carbon dioxide rises and oxygen becomes limiting, the embryo starts convulsing, a near-death experience, its head starts jerking and its egg tooth breaks through the inner shell membrane into the air cell. This is known as the internal pip.

The air cell now becomes the chick's first source of air for breathing.

Many embryos never successfully make this transition.

Choke-Point Two – External Pip

The air contained within the air cell is only a temporary reserve.

Once the chick has begun breathing with its lungs, its oxygen demand continues to increase. The air cell cannot sustain it indefinitely.

Carbon dioxide rises and the chick undergoes a second near-death experience, with convulsions and head jerks which then break through the shell and make the external pip, allowing continuous access to fresh air.

Again, many chicks fail at this second critical transition.

Why They Fail

The important point is that failing at either choke-point does not tell you what caused the failure.

The underlying cause may have occurred much earlier and can include:

• Incorrect incubation conditions.
• Poor egg weight loss or humidity management.
• Nutritional deficiencies in the breeding flock.
• Malpositions within the egg.
• Genetic abnormalities.
• Disease.
• Or simply an accident of nature.

The chick dies at one of these choke-points because that is when the demands on its body become greatest—not necessarily because that is when the problem began.

The Takeaway

When investigating late dead-in-shell embryos, don't focus only on the moment of death.

Instead, ask what happened during the previous 21 days that left the chick unable to negotiate one of the two critical choke-points of hatching.

Understanding that difference is the key to improving hatch rates.

Written by Bob Peel, Greatlander