$1:
Pretty much the whole cow is used, same with chickens.
BUlls are harvested for semen, cows are harvested for milk, beef, etc. Let's not forget leather. Usually, this will happen on seperate farms where the cows are used for one specific purpose.
Chickens, can't argue with ya there. After all, McDonald's just drops them feathered and all into electrified water to dull the sensation of the razor blade that slices their neck, and then on to the deep fryer.
It's interesting to note that some chickens can somehow avoid all the steps up until the deep fryer...