One other thing I thought of, when you pull out females, and she has a small litter (< 9) put a mark on her tail when she weans. This way when she has a second litter, and it is still small, you know she is a poor producer because of the mark on her tail from the last go around. Could work!
Nice, I love it! Never thought about permanent markers! Now even I could keep track of that. How about a mark at the base of the tail for a good litter and a mark close to the tip for a bad one. Females in the system with no marks at all have never produced.
6.13 Corns, 4.5 Ball Pythons, 1.0 Mex Mex King, 1.1 Mali Uromastyx, 1.1 Red Saharan Uromastyx, 0.1 ETB, 1.0 Boxer