Do you know what type of hay it is? There are many different types of hay, and most of them are fine for bunnies. As long as it is a grass based hay and not alfalfa, the bunnies will be fine. You only want to give alfalfa to a young (6 months or younger) bunny as it is too high in protein for an adult. Any grass hay like timothy, bluegrass, orchard, meadow, or oat hay is fine for daily consumption for a bunny.
Rabbits should have access to unlimited hay, and I find that buying a bale is the most economical way. I normally buy one bale of timothy and one bale of some other grass hay for a bit of variety.
--Dawn