dinghy hay

[Susan Kain <susankain@psinet.com>]

i just brought a new horse home for a week trial and potential purchase
pending pre purchase exam. the owner has the horse on a variety of ABC
supplements and "dinghy" hay. i've never used it or really even heard of
it, but she swears by it. would someone please enlighten me as to what
it is and what purpose it serves. she was out and did not bring any with
the horse but highly recommended i go to the feed store in town and get
some. is it worth the trip? thanks, susan