Sorry, if this is already known, but I just discovered something that appears to be a (minor) bug of MR1. When breeding a Nya by using the cat doll, you'll get a bonus of +5 on skill and speed. However, this bonus will be lost, if you freeze the offspring right after the combination.

I never knew of this, personally. Thanks for shedding light on it. It does seem rather strange that this would happen...