If they are brown eggs i can tell you that if there is a dark object but you dont see veins it still could very welll be good.
I havent had white eggs but it could also be the same not sure... If it were me i would candle at day 18 before lockdown ,see if the dark object has grown at all,
Should take up most of the egg with a small area at the bottom still clear and maybe "u" shaped.
Look and see if it moves, and smell as was said before, and then if it were me put them in the bator anyway unless the dark area only takes up less than 1/2 the egg or less . . ., Maybe dont put as close to others that you are sure are good, just in case it would blow up. Better safe than sorry but dont want to throw away a viable chick.
Lots of ppl think one isnt alive anymore and open the egg..whoops it is!!
So. after day 23 ..open a small piece of shell not membrane on the big end of the egg and see if its alive.
If alive put a wet rag around it and then put back in the bator with 75-80 humidity
If dead You might want to open them to check how big it was or if there is a chicken in there at all.Gross but you can learn a lot for the next time.
Do it outside on a paper towel. crack it first on the big end then if dead carefully crack the rest of the egg.If big end is open and stinks ..then its for sure dead
..I used a stick and sort of pulled apart the yellows etc and see what is there.If very immature it may not be able to be seen in all the yellow unless you do
Hovabator "troubleshooting chart" says;
If dead fully grown near hatch then humidity wrong or temp too cool or too warm
If they died earlier but had started to incubate then it may have been poor eggs, wrong temp (too hot /cool) , lack of oxygen or lack of turning the eggs.
I also read on the web early death can be from the eggs starting to incubate during shipping if the get over 100 b/c of high temps in trucks etc.
BUT....Hope they are ALL good little chicks for you!!
GOOD LUCK!!
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