I've had horses for over 40yrs. Sure wouldn't feed it to mine. First, I don't let mine eat milo grain,it looks too hard to digest, and milo sours easily. I feed a pelleted ration.That waythey don't die from corn mold, and they don't get crazy from that Oat High. Second, I've heard milo farmers say the leaf of some soragum,maize type plants become toxic to horses if cut late in the year.
I've fed Timothy,Bermuda,and Johnson grass without problem, so I do what has worked for me in the past.
I know feed prices, especially hay, are quite high , but I haven't had a vet bill (except coggins check) for 13yrs now on my horses. Good, clean feed has saved me money on the Vet Services.
I NEVER feed second class hay to a horse. Cows, maybe okay, but a horse can get physical problems that can never be cured. Not worth the risk.