I have been reading almost every post on every topic and the one issue that is confusing the heck out of me is fertilization.... Can someone please tell me, How do you tell if an egg is fertilized with out opening it?...What is the air sac and what roll does that play in the fertilization picture?..How long can it take to see veins?..at what point do you consider an egg a dud? Asking question helps pass the time...
The air cell is in the big end of the egg and ALL eggs have them.... they increase in size over time as air escapes via the pores in the shell. This is where humidity comes into play during the incubation process in order to help control the size of the air cell. It needs to be large enough for the chick to pip the membrane and have air to breathe until it pips the outer shell. I don't believe that fertilization has any effect on air cells. (But I've been wrong before ) Without cracking open the egg, the only way I know is to incubate them. 10 days is a good time to candle... though at 7 you will see little embryos usually. You will see a little blob with 'winglike' veining coming off of each side. But darker or thicker shells can be very tricky and you may not be able to tell for sure until day 14 or later when the egg will then either be filled with lots of veins and dark area (chick) or be clear or have a blood ring.
