I discovered this damaged egg in a sitting hens nest. It was 4 days till hatch day. The membrane was not damaged and no liquid leaking, but as you can see from picture the shell is very damaged. It is a wheaten Maran egg, I tried candling for movement, but cannot make out anything other than air sack. I could feel slight movement (or so I think, I’m afraid my mind was playing tricks on me) I took the egg and put in the incubator and locked down. Tomorrow is day 21. I am trying not to get my hopes up that this chick has a chance, but I would like to do everything I can. In cases like this should I assist in hatching? If so when and what should I do? Any advice appreciated.
Wow...that's (obviously) pretty severe damage. Since it looks like it was crushed, the chick may have been injured...but you already know that. I'd keep humidity up in the hopes of avoiding shrink wrapping - the risk will be greater with a damaged shell.
As far as assisting, I'd be looking for signs of shrink wrapping and be prepared to help if that occurs. @Pyxis posted this article on assisting hatchlings that you may find helpful. If you decide to help, go slowly, and stop if you see blood because the chick isn't ready and needs more time before it hatches.
Best wishes for your "Denty" egg to hatch! #TeamDenty
Oh gosh I hope the chick is OK. If the chick survived the shell damage, it might have trouble getting into position to hatch. This could mean it pips somewhere else other than the air cell.
If it were in my incubator, I would be monitoring it closely for cheeping. As soon as I heard it had internally pipped I would assist by carefully peeling away shell from the air cell down around the chick using tweezers. Go slow with tiny pieces to first expose the beak to ensure the chick can breathe. Stop if you see active veins in the membranes. Then moisten exposed membranes with some kind of oil or vaseline and return to incubator until the veins shrink away some (after a couple of hours) .
Repeat peeling shell some and then waiting for veins to shrink, peel and wait, etc, until you get to just the chick's lower end in the bottom of the shell where the umbilical cord attaches. It should be able to kick itself out from there. This process of assisting from first internal Pip may take up to 24 hours.