How long does the Brown rat breed for in the wild?

Question

I know they start breeding as young as 3 months but wondered if there is an age by which they become infertile. I also know their lifespan and other details but just cannot find an answer to the age/breeding question. Thanks in advance.

Answer 1

Female rats are generally infertile by 2 years of age.  Male rats are generally able to produce sperm all of their lives (although the quality decreases).

http://ratguide.com/breeding/breeding/br...