Kits born dead / stillborn / died within 24 hours of kindling
While it's important to mark how many kits your does have, it's also important to mark down how many were born dead. Some does end up producing more dead kits over time, or maybe start out with dead kits but end up having more live ones each time.
It would just be another field to fill in when you create a litter
# kits: 8
# stillborn: 3