There are a lot more rabbits being euthanized in shelters than cavies; rabbits are the third most abandoned (and most euthanized) animal in the United States. While most shelters keep statistics on how many dogs and cats they put to sleep, shelters usually do not keep track of how many rabbits they euthanize; so exact statistics can not be found. But the numbers are staggering; thousands upon thousands are abandoned at shelters and then euthanized.
I volunteer at a shelter and work solely with the rabbits and small mammals. It breaks my heart to see these innocent creatures await an uncertain future all because someone decided it would be fun to (or it would be profitable to.... or it would be a neat experience to....) breed rabbits. Most weeks that I go to volunteer, rabbits are "missing" from the last time I volunteered. I am sometimes too scared to ask the staff whether they were adopted or euthanized. Please Please do not breed, for the rabbits' sake.
Unspayed females have an 80% chance of uterine cancer (and there are plenty of other reproductive diseases). You are putting the lives of your rabbits at risk by breeding them.
If you really love rabbits, you will stop breeding and become part of the solution to stop rabbits being abandoned and euthanized. REAL animal lovers don't breed.