This is the final report.
We hatched seven chicks from fifteen eggs and, although I’m very pleased with the seven chicks that hatched, I’m not very happy about the overall result.
Of the eight that didn’t hatch, three (the two brown eggs and one bantam egg) were infertile. The brown egg layers are all old birds, which might be a factor, but they share a cockerel with the hen that laid the green eggs (all three of them hatched) and were collected clean and fresh so I had expected better.
The other five were all bantam eggs and come from just one hen. The infertile egg may well have been caused by the fact we had to store the eggs for two weeks to get enough to hatch. I should have marked that laying dates on the eggs so I could check the correlation with hatchability.
The ones that didn’t hatch were a mixture of mid to late term fatalities and were rather black inside.
Looking at all the possible causes I think we can ignore temperature, humidity, power failure and poor turning as they are all taken care of automatically (though I will test the temperature next time I set it up to check the accuracy of the built-in thermometer). They are on a good ration so I’m going to ignore poor nutrition for now.
That leaves inbreeding, poor ventilation, diseased or infected eggs and lethal genes.
I know what a lethal gene is, but I haven’t a clue how it would show itself.
I can’t vouch for ventilation – I will probably ventilate more in the next attempt and see what happens.
However, as the weight loss from evaporation was what we expected I’m assuming that humidity and ventilation were about right.
In truth, I can’t remember the parentage of the breeding stock, as they were passed on to us without much detail. The bird that laid and hatched the clutches of 11 and 8 on top of the coop is a half sister to the bird that laid these eggs but the “half” may make a difference.
That leaves diseased/infected eggs, which was my fear from the beginning. Our nest boxes aren’t brilliant so there is often dirt on the shells, which can allow germs into the egg via pores in the shell. That, plus the length of time we had to keep the eggs, is probably the cause.
I’m going to do some calculations now and see what I can do to improve.