Most dairy farms in Wisconsin continue to follow a fairly generalized formula of how to produce milk. Cows and replacement heifers are fed primarily homegrown feed from crop rotations comprising alfalfa (Medicago sativa L.), corn (Zea mays L.), oats (Avena spp.) and soybean (Glycine max L. Merr.). Protein and mineral supplements are purchased to compliment dairy diets. However, the dairy industry is undergoing rapid change to remain economically viable. Many farms are expanding herd size and increasing the importation of feed. Greater livestock numbers on a fixed land base has increased the risk of soil nutrient buildup and environmental pollution.