Chicken fertility

[AmandaBraddick]

Hi everyone. I put 4 araucana eggs in my incubator and out of 4 only one is fertile (just candled day 9). These were collected over 7 days and the fertile one is the newest. Annoyingly the next egg laid that didn't make the incubator was fertile and so were the two before the incubated ones. How can a chicken lay eggs over a period of 10 days some fertile and some not? I thought on one mating eggs were fertilised for quite a few days. Any help gratefully received.

 

[Lady of McCamley]

Did you crack them open and determine they were not fertile? Just because an egg doesn't develop doesn't mean it was infertile. There are a number of reasons the embryo doesn't form, one of them being never fertile.

Araucana, as I'm sure you are aware, are notoriously bad breeders (I'm assuming you are using the US rumpless standard) due to the poor anchoring by the rooster from being tail-less. The rooster may have, uhm, had poor aim and poor connection with the hen not providing a "full load."

Also Araucana are notorious for poor development if both parents are tufted as 2 tufting genes are fatal to the chick. (Though embryos, as I understand, die in the shell later on in the process).

So I'm not sure where your eggs were in fertility process. Obviously you want to always set your freshest with day 7 being the earmark for declining fertility in most breeds.

So it may have been poor coverage by the rooster, poor uneven temp in the incubator. or frustratingly an embryo that simply did not develop.

EDITED to add: And if you are using an older rooster, his fertility may be waning such that his sperm has lost some spunk making some of "his" eggs duds.

My thoughts
LofMc

 

[AmandaBraddick]

Thanks for your reply. These eggs were a bit of an experiment as the only rooster i have is a silkie and ive never seen him mate her. I do have a very large Orpington which is always "mating" my hens but im not convinced she's a he or very bosy hen doing it for dominance. Hence the experiment to see whether the chick will be a silkie or Orpington cross.
I cracked the eggs open and they weren't fertile, jusk yolkers. I've posted photos of her eggs on here before (in case i was getting it wrong) and had them confirmed fertile by the experts! All my flock is under a year old.
I didn't realise Araucana were bad breeders to be fair but is it just the rooster that has problems due to balance or would it be difficult for any rooster to mount an Araucana hen because of her tail feathers?