Dying before exiting the shell

[riktheimpaler]

Hello
I have started hatching duck eggs. Probably 50% of my eggs have hatched with help and the other 30% are dying while in the shell within days of due date. I have been watching temps and humidity regularly and believe they are all up to spec. One consideration that escaped me is the feed!!! I have been feeding the ducks the Dumor brand layer pellets. Is there a possibility the layer provides too much mineral and the shells are too hard to escape?? I have checked the shells and they are extremely strong.
Anyone had any experience with this problem and switch feed to grower / finisher with better results? Please let me know. Thanks!!! I have 60 more eggs in 3 incubators and am not looking forward to hand peeling them to try and save their lives.

 

[Shamo Hybrid]

I would not set the humidity soo high nearing hatch date, people overdo it in my opinion. 40% throughout and I had near 100% hatch rate with only 1 poor booger who pipped, zipped... but couldn't dipped outta the shell!

 

[tdan]

I've hatched plenty of pekin with rock hard shells. Most came out but had to help some that were trying to come out. If i was down to the last half I'd look into helping out. Or let nature happen and get strong ones, up to your preference.

If it's 3rd gen inbreed, could just be weaker ones not making it. Might need a new drake to change genetics.