Effect of prolonged cooling on late-incubation eggs

[FenDruadin]

I just had four eggs hatch out of seven from a batch that started under a broody, which is a lower-than-usual hatch rate for me. I believe it may be due to the fact that they were chilled for several hours about a week before hatching, and am wondering if anyone has any experience or stats to back up (or contradict) my intuition on this.

Details: The eggs were cold when I found them. The hen had been taken by a predator some time during the night. Nevertheless, six out of seven were living when I candled. Still, first one then another died over the following week, and then very quickly rotted and stank. Four that did not rot hatched successfully, although one was stuck in the membrane even though the humidity was right, and had to be helped.

The quick rotting surprised me. Usually when I've had one die, it can go days or even a week without showing external signs. But these started stinking within a day or two of dying, and one started to ooze.

Question: Is it likely that the babies that died survived but were weakened by the prolonged cooling period, and that's why they died? But why would they rot so quickly? Did the cooling allow the introduction of bacteria that otherwise wouldn't make it into the shell?

Thanks for any thoughts--

(Edited subject heading to more accurately reflect content--)

 

[Elite Silkies]

I guess it would depend on how long and how cold. Someone unplugged my incubator and it dropped to 75 degrees (Not sure how long) but all but 2 died. One of those hatched.

So, I certainly think that when the temp drops for a long period of time, it drastically reduces the hatch rate.

Not sure, why they started rotting so quickly. But, I don't think it takes that long for an embryo that has died to start rotting. A matter of 24-48 hours I think.

 

[Kedreeva]

I've left dead eggs in the incubator for days without any smell. 'Rot' is the breakdown of tissue by bacteria (not all bacteria is bad) and the stench is really the chemicals emitted by the bacteria as they eat. So my guess is that if they rotted so quickly, there was something up besides being cooled for a while.

 

[FenDruadin]

Thanks--unfortunately, I have no idea how long they were cold for. It could have been all night, it could have been two hours. The temp was around 75-78, but had been cooler during the night. They were quite, quite cool to the touch.

I appreciate the feedback--I also have had dead eggs in the incubator for a week and not had them rot. So I agree something else must have been up.

I wonder, though, if the cooling might have made them more susceptible to a bacterial infection? That might have caused the death as well as the quick rotting...?

The four who hatched are doing well, so I'm grateful that many made it.