Of the three, switchgrass is probably the most widely planted. Switchgrass seedings tend to be more successful than the other two grasses and it's just easier to seed. The seed is smooth and works well in many seeders. Both species are more palatable than switchgrass after heading. Their low production time is in the middle of the summer.
Smooth bromegrass is probably the most popular cool season forage grass in Iowa.
It grows readily on most soils, spreads by underground roots, and can take a beating. Bluegrass is like a little sister to bromegrass. It can take abuse and spreads by root. Yield of bluegrass is appreciably less than bromegrass. If abused, it will probably die out.