Sky had only ever eaton grass hay before I bought her. I planned on keeping it that way since, at the time, grass was cheaper than alfalfa and if that's what she was used to, I saw no reason to change it. Well, one day I show up to buy hay and the grass looked just awful. It was complety yellow on the outside, so I refused to buy it and got alfalfa instead. Even when the grass hay looked better, apparently there was a huge shortage and the price of grass passed the price of alfalfa. Here in Az I pay $15 a bale for grass and Alfalfa is about $12. So anyway, I chose to continue feeding alfalfa, until her face slowly started to break out in sores. It got so bad that the hair around her mouth and eyes started to come off in chunks. That's when I had the vet out who filled me in on the problem (I had never heard of photosensativity before that). He said to switch her back to grass only, and that's what she's eaten ever since.
Oh and it's Bermuda grass.