When I lived in Georgia, it was one of the favorite things for my goats to eat. I would always throw them the greens when I would cut some to use for something. I think tall bamboo would be an excellent forage, particularly in the winter or droughty times when other stuff isn't growing, and it's up out of their reach the rest of the time so you have to go and whack it so they can get to it. Just keep the critters fenced out during the relatively short period in the spring when the new shoots sprout up. A
fence around a patch is a good way to keep bamboo from spreading too fast, too, since grazers will keep the new sprouts eaten off. Zone 4 does seem to be kind of cold for most bamboo though....
