What do you call a cat of breeding age?

There isn't a specific term for a cat of breeding age. However, you could use terms like:

* Mature cat: This is a general term that applies to cats that are past kittenhood and have reached sexual maturity.

* Breeding age cat: This is a more specific term that indicates the cat is old enough to reproduce.

* Stud cat: This term is used for male cats that are used for breeding.

* Queen: This term is used for female cats that are used for breeding.

The best term to use will depend on the context.