I have grapes covering my run and the chickens love the vines (I do too). The leaves are one of their favorite green things to eat and they love eating the grapes within jumping height. The grapes don't fall off and rot where I live--they turn to raisins on the vine if I miss harvesting them. We try to collect all the grapes to make raisins where the wild birds can't get to them. There is some work involved with pruning back the vines every year. With the addition of the wire run around the vines, it now takes me about an hour each winter to trim the vines, which I don't think is too bad. You can see pictures of the vines on my byc page.