We have one here that is soon to meet her demise. It is a Dexter cow that has decapitated and stomped to death almost every one of our Buff Orpingtons. This cow has been a nut bar and aggressive since day one but never touched a chicken until a few days ago. Now she chases them down and kills them on sight. Locking chickens up did not work as she just broke the fencing down. BTW this is game fence that is normally used along the highways to keep Elk and moose off the roads with 6 inch round posts. So almost 50 Orpingtons gone and years worth of selective breeding down the drain. Those steaks had better be really good quality after this.