Summary Four different systems of feeding and managing dairy cattle are seen in major milk-producing countries. These are (1) feeding purchased roughages and concentrates to zero-grazed, intensively penned cows; (2) home growing of roughages and most concentrates for zero-grazed animals; (3) feeding concentrates with conserved pasture and other roughages in winter and reduced concentrates to grazed cattle in spring-summer; and (4) feeding cattle on grazed pasture and conserved pasture throughout the year. The following data on the four systems were obtained from examples in southern California, Wisconsin, England/Wales, and New Zealand. Average fat-corrected milk (FCM)/cow is approximately 7,140, 5,300, 4,670, and 3,475 kg; output/ha 4,700-10,000, 4,400-5,300, 5,200-5,800, and 7,000 kg FCM; and hours/cow 60, 70, 48, and 30 in the California, Wisconsin, UK, and New Zealand examples, respectively. In energy output/input, the grazed pasture system is probably 3 to 4 times as efficient as any of the others. Milk-production costs in New Zealand are only about 40% of those in the U.S.A. and UK, and it was calculated that dairy products from New Zealand could be landed in the U.S.A. at about two-thirds the cost of locally manufactured products. Much higher costs are incurred by countries such as Israel and Japan, which have to import feed and fuel. The protection of local dairy industries from competitive imports is leading to the need for subsidies, quotas on production, and a reduction in milk consumption and to a decline in the production of dairy products from temperate grasslands.