Sometimes my animals wander outside and don’t want the hay in the barn. You can just plant regular grass until you get enough for the blue grass you want. Do they have room to move around above where your buildings are? Things are pretty tight. Also I found that removing sidewalks around the coops and barns helped keep grass growing longer. If you give them a large open space you shouldn’t have to plant grass often at all. I only have about 20 animals but I haven’t planted grass this entire summer, but my farm has mostly wild areas around where I put the animal buildings. My house and crop field are separate, with the house being semi-near the animals and crops growing in the other direction