I grew up in Southern Illinois so I know what the climate and soils are like. If I were raising cattle there, I would have at least half of my acres in a fescue-based pasture. Why? November thru March there is no lower cost way of feeding cattle in that part of the world. There should be no reason you should ever have to feed hay there if you manage the fescue appropriately.
With a sound grazing management plan, endophyte-free fescue will persist there and you would have no animal health issues. Planting one of the friendly endophyte varities costs a little more up front, but over the life of the stand the added cost is negligible and the persistence benefits make it worthwhile.
As a couple fo the earlier posts said, include clovers and some other grasses and even endophyte infected tall fescue can be good pasture.