Mechanically Recovered Chicken

At break yesterday conversation revolved around a bargain purchase from Tesco's. Did you know they are selling hot dogs made predominantly from 'Mechanically Recovered Chicken'? I love that, 'Mechanically Recovered Chicken', though not to eat you understand. It just gives me an image of small robots running around the farmyard after panicked hens. What it all has to do with hot dogs I will never know.