Even though it’s not much
fun, I autopsy all of the eggs that don’t
hatch after 23 or 24 days.  At first, I found lots of partially or
fully formed chicks during my post-hatch autopsies, but as I got better
at incubating, more and more of the eggs that didn’t hatch were simply
full of liquid and no chicks.  Of the 24 eggs we stuck in the
incubator at the end of July, 14 hatched, 2 were nearly fully formed
but died in the shell, and 8 showed no sign of chicks at all.



Chickless eggs can have
several causes.  First, it’s quite possible that the eggs were
never fertilized, especially since my later hatches occurred long after
the peak egg fertility period.  The chart below, which I mocked up
using data from The
Dollar Hen, shows
that hatch rate (and, presumably, egg fertility) follows the seasons,
with lows in July and August and again throughout the winter.  To
get the most  bang for your buck, you might choose to order eggs
during the peak fertility period in middle to late spring.



Another cause for chickless
eggs is embryos that died within the first few days of
incubation.  If you’re very astute, you might see spots of blood
in these eggs, signaling that the egg was fertilized and that a
miniscule chick started to grow.  You have to expect a certain
number of eggs like this when ordering
eggs through the mail
since longer storage, rough handling, and temperature extremes before
the egg goes into the incubator can all kill your chick before it
really begins to grow.  If you see lots of chickless eggs from
homegrown eggs, you should instead consider the viability of the
parents — are they healthy, on pasture, and young; do you have the
right number of hens per rooster; is the flock suitably outbred, etc.?



I ran across one final
tidbit while researching infertile (or seemingly infertile) eggs —
your hatch rate will probably correspond to the apparent fertility rate
of the eggs.  For example, since 67% of our eggs from the last
hatch had some signs of chick development, we should have hatched only
67% of the fertile eggs (11 chicks.)  Many of the factors that
cause embryos to die very young also make the surviving chicks weaker
and unable to survive all the way to hatching.  So I guess we got
lucky hatching out 88% of our fertile eggs into perky chicks.

In our last hatch of 2011,
all of the chicks were very vigorous and didn’t need help, except for
two eggs in which the chick had developed backwards.  Rather than
having its head at the large end of the egg, where the chick had plenty
of room (well, relatively speaking) to maneuver around, both of these
troubled chicks tried to peck out of the pointed end of the egg.



Thirteen hours after the
first troubled chick pipped, I decided to go ahead and help it
out.  I’d read that a chick who pips at the narrow end of the egg
has a death sentence unless you
help it, and I
wanted to see if this chick could survive.  So I heated up some
warm water, dampened a cloth, and started to peel away eggshell. 
As I tore into the membrane, blood pooled under my fingers, and I knew
I had jumped the gun.  Apologizing profusely, I cleaned up the egg
and put it back in the incubator, where I worried myself sick about the
chick for another nine hours.



At 24 hours post pip,
the chick began to struggle furiously, but made no headway on
hatching.  Once again, I took the egg out of the incubator, this
time discovering that the morning’s blood had dried onto the chick’s
feathers and glued them to the membrane.  More warm water, a bit
more picking at the shell and membrane (which no longer bled), and the
chick was free.



Meanwhile, a second egg’s shell
had been penetrated by a backwards chick, but I was leery of helping
too soon due to my bleeding membrane experience.  Instead, I left
the egg in the incubator, and 22 hours later, the chick hatched
completely on its own.  I guess pipping on the narrow end of the
egg isn’t a death sentence!  Unfortunately, the chick’s valiant
struggles injured one of its feet so that the toes
curled under and the
chick was unable to walk straight.  I’ll post more about our
reponse to that problem once I know for sure how it turned out.



The chick from the egg I
helped (even though I mangled the operation the first time) is just as
strong and healthy as the chicks that pipped at the blunt end of the
egg, while the chick I didn’t help is going to need some TLC and will
probably never be perfectly cured.  My experience from previous
hatches lines up with these results — chicks that need help but don’t
get it tend to injure themselves getting out of the egg.  I plan
to be even more vigilant about aiding chicks in the future.