I have a love/hate relationship with blackberries. They are growing in several areas close to my house and I have feasted on and have been mangled by them in turn. I love the blackberries and so do my pigs but the vines were still very low to the ground- they spread like grass cover here. I don't know if there may have been problems with tall bushes. I would let my pigs go at them though. I have razorbacks- maybe you can find some near you. Razorbacks don't care what it is- they will eat it.