We always considered hay to be cow hay if we waited a little too long to cut it and it was a tad overmature. It might have been a bit stemmier than we would have liked for our horses. However, if we messed up like that and hay was in short supply, we fed it to our horses anyway. Never had any problems.
The hay we're feeding now is all native grass hay. It was cut just a bit later than we would have liked, but it was rainy when the hay was just at the right stage for cutting, and we figured it was better to let it get a little rougher than to cut it and let it ruin, just because it was at the right stage. Our horses are gaining weight wonderfully on it. Junior, our sickly one, has nearly doubled his weight since we started putting out hay. He looks great! Even Dancer is gaining weight!
Oddly enough - we didn't fertilize the hay this year - the hay meadows had been laying fallow for several years, so the hay was even a little weedy. Early this spring, we'll fertilize and overseed with oats and bermuda grass. (Odd combination, I know.) We'll cut just before the oats head out. Don't know why, exactly, that's just the way hubby's family has always done it!
Plain Old Dee, horses Dancer and Rain I believe in dragons, unicorns, good men and other mythical creatures!