Well, the war caused a boom, because soldiers need to eat, and men (Sorry for the stereotype) normally like to eat meat, as well as the fact that it is good for them. So they would be willing to pay a fair amount of money for a large amount of cattle, as there are many soldiers who need to be fed. As for the bust, if there are too many cattle around and no one needs the meat or would pay for them, then there is no use for the cattle.
