sentences:  Some farmers elected to move their bulls by tying a rope to the ring and tying the other end of the rope to a farm tractor, providing both motive power and a degree of protection from the angry bull.The efficacy of this technique is doubtful, and may depend on the size of the tractor and of the bull; one authority has "seen a bull lift the front end of a tractor like a toy".Others used dogs and horses.