Dairy farmers, as profit maximizers, are constantly striving to expand the income producing ability of their dairy herds. As managers of their business, their direct concern is to attain high production per cow and enhance the average quality of their herd by removal of the unprofitable producers. They are also striving to earn a large income above feed costs, since feed costs comprise 50 percent or more of the costs of production. This value must be high enough to pay for the other costs of production, including a return to capital and operators labor, to return a profit. Proper culling or the identification and subsequent removal of the lower producing cows from a herd is important because of the increased average milk production and the resulting increased income above feed costs.