What is this plant?
This plant is called Thicket Creeper, Parthenocissus vitacea, and is a member of the grape family. 2,4-D and Triclopyr are two products that can be effective on this plant, though extreame care should be taken if you are near an vineyard as it can damage the grape plants as well. Always follow the label on any pesticides used.
I have a call out to confirm, but it appears goats may be able to be used to mitigate this plant as well. I have not found any source to suggest that it is toxic to livestock. If you are interested in using livestock for control, please contact me at 541-278-5403 and I can follow up about using goats.