I'm so excited, I found it!
I scrolled through and cause embryonic mortality starts around page 51. Don't know if it has early chick mortality or not. But there is SOO much good information for hatching there...
https://www.hubbardbreeders.com/media/incubation_guideen__053407700_1525_26062017.pdf
Have you already found this valuable resource?
https://www.backyardchickens.com/articles/hatching-eggs-101.64195/
I personally would stick with just my own eggs. And try to find out what's going on. Without risking bringing anything into my flock that isn't already there.
