I generally candle at day 10, 15 (generally only if there were questionable ones from the day-10 candling), and day 18. And then if some that were set for hatching don't hatch after day 24+ I generally candle those again to see if I can see any movement. (This would be for chicken eggs, of course)
A lot of it depends on shell color and thickness as well as what you want to accomplish with your candling. White/light shelled eggs you can often see something by day four though day seven you'll see more clearly. Brown, green/blue chicken eggs and turkey eggs I don't candle before day 10. Too hard to tell for sure what you're seeing. We don't candle again after that until day 19 for chickens or 25 for turkeys which is when we move them into the hatching trays. This shows us the quitters that need to be tossed (no stinkbombs in the incubator!). If we're doing an embryology lesson we might candle every two days.
A. T. --Thank you for that word of advice! My eggs are at day seven and I candled them last night. On three I could clearly see the viens and dark spot, on four I could see the dark side and air sac, and two were positively opaque. When I realized it was all the white eggs that seemed alive and the brown and green that didn't I desided it was too big of a coinsidence to be real and had more to do with my improvised equipment. I must say mama was relieved I put them all back!
I agree, When I first started hatching I would candle almost every day to see the development progression. Now I candle on day 10, and you can see which ones are either infertile or which ones have quit, and then again at lock down.
This is my first time hatching and I hang my head in shame...I cannot help myself...and I will probably pay the price when none of my 8 silkie eggs hatch. But I watch the hen with her eggs and she is way rougher than me. I can't help but look to see what is going on. On day 4 I could see veining and a dark spot Day 5 and 6, bigger dark spots bobbing around Day 8 (today) way bigger darker spots...less movement I am addicted to the process...probably once I do a few hatches I won't have the uncontrollable burning desire to candle. I hope I am not hurting them at all.
