AmysMacdog":1v88egft said:
Fodder is Forage- green foods like weeds, tree branches
Silage is fermented hay
Hay is dried/cured grass
Straw is dried wheat grass (stems)
I like Amy's answer best so I will expand upon it.
Fodder = forage= any food an animal gets for themselves, usually pasture or some kind of green plants, but can also be seed, acorns, etc. Of course with rabbits this means any fresh food or seeds their owner brings them.
Silage is fermented forage. It can be grass, corn, grain, alfalfa, almost anything.
Hay is dried/cured plants. It is usually grass, but can be clover, alfalfa, immature soybeans, etc.
Straw is the dried stems of a cereal grain. While it is usually wheat, it can also be rye, barley, oats, etc.
Dried pine needles are also sometimes referred to as straw.