Fescue and endophyte.
You can mitigate a lot of the affect of the endophyte by diluting it with another forage. We use clover and OG. Pastures are in the 50-70 year old range. Never had it tested, but because of the lushness and the persistence most of the wizards around here think that it's got a very high endophyte contamination. Of the grass, fescue makes up probably around 80-90%, but most pastures are also 30-70% clover. On the other farm when we added RC to the fescue our weaning weights went up 50lbs per cow on average. The biggest problem we're having is the cows being too fat. The poorest they get anymore (other then one cow) is about BCS 6-6.5. On stockpiled fescue over the winter come spring they calve at around a 7-7.5. Calving interval runs 11 1/2 to 12 1/2 months. but over a cows life time it averages out to just under 12 months. We start breeding the 20th of May so any body that was in heat the week before will be 3 weeks later calving then if we bred them earlier. This past calving season was 36 days and that last straggler was 4 days late.
I personally hate fescue, but in this part of the country if it wasn't for fescue there wouldn't be any beef cows.
Once the seed gets to the point that it will easily strip from the stalk we clip the pastures before turning the girls in.
To use fescue takes some managment that isn't required for other forage bases. I think that once you get the balance of something to dilute the endophyte and the fescue that it can really work for you.
If managing it isn;t desired, you can graze the snot out of it continuously and it will stand up to it. The price is poorer performance of the cattle. Cattle that have been raised on endophyte fescue and are from adapted cows don't have problems with shedding out/rough coats, etc. None adapted cattle tend to have more problems in severe winters with loses of extremities, mostly the switch but sometimes hooves and ends of the ears also.
dun