There actually isn’t much evidence of endophyte having negative effects in goats, mainly in cattle. Protein is the main differentiator in types of hay, with alfalfa being the highest percentage. If you feed mixed grass hay your goats may need to consume more to get the same nutritional value as other options.
I would watch that they don't drop weight while on it; though I suppose it depends on what stage it was cut in. I think (not 100% sure), that the protein value of it goes down the longer it goes to seed?
Oat hay is usually available here for a short period in the spring usually the first hay cut
My goats love it but the calcium to phosphorus isn't great
We usually have no choice but to feed some fescue in the spring
Our main hay is Bermuda but it is cut later
But my hay guy usually doesn't run out of the last year's Bermuda until he cuts some oat and then fescue
The only option we have around here is a fescue/grass hay so I give alfalfa pellets to supplement. They waste less of the pellets than the alfalfa hay and so it costs less. When they're full of alfalfa they'll choose not to eat any more.
After alfalfa triticale is my second favorite. It cut before it goes to seed it is as good or better then alfalfa minus the calcium. Wheat is after that, then oat hay. But you want beardless wheat.
I don’t like any grass hay because my goats don’t like it which makes sense why would they eat a dry grass when they have it in their pasture. It can also be just as expensive as alfalfa now that horse people have figured out that most horses don’t need alfalfa especially ones that simply sit there most of the time or go for little rides here or there.
But lstein is correct the longer a grain hay matures the more the protein value goes down, they will also be way worse on wanting to waste and they will pick the seeds out and nibble on the rest.
Bermuda grass (Tipton 85) A great hay that if grown properly will produce 15-17 % protein. My cows don't have to be fed grain while eating this hay during the winter. The goats love it and stay fat as killing pigs on it. That is providing the parasites are under control as with any hay or feed.