the vast majority of the soy that is fed to livestock is the industrial waste from pressing it for oil. feeding it to animals is conserving resources.

edit: about 7% of the global soy production goes directly to livestock. about 17% of all the end uses of soy is as soybean oil. since a soybean is only about 20% oil that means that 85% of all the soybeans in the world must be crushed for oil. The industrial waste from that process is called soy cake or soymeal and that is what is fed to livestock. if we didn’t feed it the livestock it would be a waste product.