livestock are fed to make a profit. feed costs make up about 75 percent of the total cost of raising an animal.the ration must be as cheap as possible while still meeting the farmer must be careful not to lower the nutritional value of the ration by using inferior poor-quality feeds. it is generally less expensive to use homegrown feeds rather than commercial feeds. commercial feeds should be use only when homegrown feeds are not available. they may also be used to supply nutrients not provided by homegrown feeds. rations must be carefully balanced to provide the best nutrition at the lowest possible cost