If you have an animal, such as a Horse or rabbit which feeds on Hay, what (if any) nutritional difference is there between "Hay" and "fresh grass". Obviously, Hay is grass that has been sun dried to make it more storable. Are there chemical or protein changes that occur to grass that has been dried into hay? I suspect that as the plant dries some sugars are turned into starch. If you have a reference source with an answer to this question I'd appreciate it.