A common question that we get is if the eggs, whether they are the eggs they receive from us, eggs their own ducks are laying, or eggs they find out in the wild, are fertile. The simple answer is that we do not know.
One way to find out if your egg is fertile is to crack it open. While this does prevent you from incubating the egg, it does tell you if an egg is fertile. Maybe you just wanted to check to make sure your single male was fertile. It is also a great way to check fertility if you are eating some of your eggs. If you look closely at the yolk and see a white doughnut shaped spot, then the egg was fertile. If the white spot was solid and irregularly shaped, then it was infertile.
Top: Infertile Egg
Bottom: Fertile Egg
The only way to find out if your egg is fertile without cracking it open is to incubate and then candle the egg. This normally takes about six days before you can clearly see development in the egg. You can use our candling photos on our website to track the development of your eggs.
If you do not see development after six days, we suggest you continue incubating as it could be that your flashlight is not strong enough (see our candling page for explanation). If you don’t see anything by ten days, then you know for sure your eggs were either infertile or died very early in development.
We guarantee that 80% of our eggs will be fertile and alive at first candling. This does not mean that we guarantee 80% hatch as there is also a spike in mortality the two days before hatching.The most common times for the embryo to die are the first several days of incubation and the last several days before hatching. So an egg that died early in incubation was truly fertile as it started to grow, but oftentimes these early deaths and truly infertile eggs are called “infertile”. This early death can be caused by many things and is typically caused by incubator conditions - over which we have no control.