It's a really old-school thing to feed rabbits, and I wouldn't recommend it as anything more than a treat (and not a whole piece of toast). The carbs in toast aren't very good for a bunny's GI tract because they can make it slow down and stop moving things through quickly. However, like anything, in moderation I'm sure it's fine. I haven't given any toast to my buns, but they will beg and beg and beg for cereal (I rarely give in, but the bf does!) in the morning and Muffin got hold of a poptart once and loved it (also not reccomended!!). They seem to know it's bad for them so they like it even more! Just like me and chocolate...