Funky fish is right,
mums bring home dead food for babies, then maimed food to get them used to a moving lunch ( or a running buffet) and then un maimed food ( well, almost) to help them practice hunting. They usually call the babies out of their hiding places by mewing to announce that dinner is served.
So when your cat comes home calling and carrying a cadaver its time to wash your hands and sit at the table
When they bring the dead prey back to the kittens they re enact the kill to give the babies an understanding of how to respond to prey. This includes eating the prey in front of the babies. Kittens learn so much from watching mum so watching her eat it and groom herself afterwards is all just as important as learing to kill.
So when your cat toys with its prey and eats it in front of you take notes...next time its your turn
When the babies are older mum brings back maimed pray, calls them and then sits back and leaves them to it. Sometimes the babies loose the pray or kill it but don't eat it. But once she brings the prey back for the babies (or places it on the step for you) Mum will ignore it. They eat fresh kill not carrion so once its stiff none of them will eat it.
So once she brings it back and sits back while it runs round the room.....she's handing over full responsibility to you
As this is a basic instinct its imprinted in her and other cats. Though some cats, both male and female do it more than others. Both nature and nurture will contribute to this as will the supply of mice ( the move plentiful the supply of mice the more live ones are brought in)
In some cases interupting her when she is toying with her prey can make her more likely to do it somewhere else in future. But this would only work if you interupted her while she was still thinking of eating it. You see cats don't hunt as a group or share a kill like say lions or dogs. Despite everything that I have just typed about hunting food for others, food that they hunt for themselves is eaten by them and not shared ( babies or no babies!)
Perhaps setting up a pasport control check point at the door is the best way.
It must be hard being a cat, going out each day to hunt and bringing back the spoils to us bald, two legged idiots who respond with revulsion and a serious lack of appreciation
Poor Puss,
Buffy