Yes, there was a pair of those in the shed here when we moved in, and I used them a few times on large chickens. On the whole, they worked well. The knack was to use them in conjunction with a cone. Position the pliers at a gap between vertebrae, then both clamp and twist to separate the spinal cord.
Personally these days we use an air rifle to stun (TBH it's invariably all over after that anyway), followed by neck dislocation with a broomstick.