Our neighbor doesn't believe in spaying his barn cats, so his cats and ALL the neighborhood cats are coming to our barn for all night rat-catching parties, and sometimes daytime parties, too! Our doofus male cat, Inky, will OCCASIONALLy kill a rat if it's not too big...but his main thing is to keep all the other cats from encroaching on his domain and killing HIS rats!
And Tippit, Inky's half sister, is afraid of big rats. Period. Her thing is to kill baby snakes...who would grow up to eat the rats, if they could!
The other night Inky quickly came in the house and went under the table, where I thought he was playing with a catnip mouse, til I went to pick it up to throw it for him...EWWWW,GROSS! You guessed it, he had a baby rat, it was raining outside, he wanted to bring his gross, slobbery, wet, bloody rat inside to play with.
We have had very bad luck with traps; live traps work the best, and even then it took us a few weeks to catch just two rats. I once talked to someone who said her parents would keep ferrets in the barn to kill rats, but I think that would be cruel to the ferrets.