Horses only require 7% to maintain..15% is what I call dairy quality...horses will need less of it to maintain, but since they are grazers and you will be feeding less..causes anxiety if they have nothing to do all but but wait for that little flake.. without the roughage a horse requires from lower protien hays, you stand of chance of colic since the gut isn't full.
If the horse is stalled, you will also get a higher usage of your bedding since alfalfa makes them urinate more... good source of hay for a working horse though.. I would get some of his and mix it wil a lower quality hay if you could...
Green don't mean good quality nowadays..especially with the high use of drying agents..
Horses find it bitter to eat and will actually go off their feed to avoid eating it. It can cause ulcers.. when you chew hay it should taste sweet..