I think it's okay when mixed into their daily food supply, but giving open access to alfalfa hay instead of timothy is more the problem, because straight alfalfa is too rich for adult rabbits from what I've heard. We were going to do pasture silage and thus grow an all purpose pasture good for all our livestock, but Silage is looking to be a huge pain in the butt so we'll probably just bale it into hay instead. It'll mostly be timothy grass, but I did want to plant orchardgrass as well. This would then be ground and run through a pellet mill (if we can find one) for the winter months when there is too much snow and the chickens can't/won't forage, in addition to sprouted greens and other goodies daily to keep them healthy and happy.
I suppose if I grind it and make pellets it would be fine for chickens, but what do you think about making hay out of our pasture? I'd wanted to plant orchardgrass, timothy grass, perennial ryegrass, and a bunch of weeds like dandelion, purslane, maybe some clover, and maybe add some herbs like thyme and mint in there somewhere. Would the chickens be able to eat this alright, or would it be better to just grind it into pellets?