I never have (they don't grow here), but since it is an edible plant, I don't see why not.
Of course, if you have a single goat, and a forest of loofah vines, only feed a little at a time (a small portion each day). A huge amount of any new food could be a problem.
I always look up toxic plants. You have to keep in mind that some parts of plants are toxic, other parts are edible. For instance I’ve seen apples on the toxic list because the seeds contain tiny amounts of cyanide. Really? You’d have to eat a huge amount of apple seeds! Look up toxic plants, then research that particular plant to find out what parts are toxic.