How long have you had it? Many farmers will keep hay for a whole year (or 9 months or so) after the last crop is gathered and before the new crop starts. So hay can be stored for quite a while as long as it’s in a cool, dark, dry (being dry is very important) place.

Does it smell funny? Moldy or musty? Does it look different?

Proper storage is very important. Many of us buy hay in bulk because it’s cheaper and more convenient, either high quality horse hay from farms or bulk boxes of hay from companies like Oxbow or American Pet Diner. It should be able to keep for quite awhile (months) if stored as Elrohwen suggested. Air circulation is important too.

How long have you had the hay, what type of hay is it, where is it from, how are you storing it… Is it dusty, brown, musty or moldy-smelling?

Hay doesn’t really expire-but it can get moldy. It’s very unmistakable so likely that wasn’t the issue. But when they bale hay-the outside of the bale can get yucky brown-depending on the process: soo even though it wasn’t moldy it could have been just yucky from being too dried out by the sun. Anyways glad the buns are eating their new hay!

Good point, K&K. I have a timothy tunnel that’s been bleached and dried out by the sun and Otto won’t even give it the time of day anymore. Even if it’s perfectly fine, bunnies can be picky about what hay they’ll eat.