There is a strain of fescue that has been developed to be endophyte free, but it is not very drought resistant. ( we had no success in getting it to live thru our hot dry NC summers) Plus you could not let it go to seed, if it did the "new" grass had the endophytes. The endophytes actually make the grass more drought tolerant (a symbiotic relationship)
Also there is now a strain of fescue that has a "friendly" endophyte. It is drought tolerant. We seeded our pasture with a mixture of that, clover, alfalfa, and a couple of other grasses. We were buying fescue last winter from a cattle person who grows the endophyte friendly hay. ( the endophytes are not good for cattle either, while not as harmful as to equine fetuses, it still causes reproductive problems and milk production problems.)
Since Fescue is the "best" growing grass in this area, many folks choose to feed it, you just have to pull your pregnant mares off of it 3 months prior to foaling.
You can have the hay/grass tested to see if it is free of enophytes or has the "good" endophytes.
If your hay guy does not know what it is, chances are Fescue does not grow in your area and your hay is another species of grass.