Huge productivity gains in agriculture were recorded in the twentieth century. Avoiding losses of agricultural products to spoilage, insects, and rats contributes significantly to productivity. Large amounts of hay stored outdoors were traditionally lost to spoilage before indoor storage or other means of coverage became more common. Pasteurization of milk allowed it to be shipped by railroad. (It was noted that calves fed pasteurized milk were less likely to develop tuberculosis, and soon it was found that pasteurization reduced the incidences of several other diseases in humans. ) Keeping livestock indoors in winter reduces the amount of feed needed. Also, feeding chopped hay and ground grains, particularly corn (maize), was found to improve digestibility. The amount of feed required to produce a kilogram of live weight chicken fell from 5 in 1930 to 2 by the late 1990s and the time required fell from 3 months to 6 weeks.
Between 1950 and 2000, during the so called "second agricultural revolution of modern times," U.S. agricultural productivity rose fast, especially due to the development of new technologies (the greatest period of agricultural productivity growth in the U.S. occurred from World War 2 until the 1970s). For example, the average amount of milk produced per cow increased from 5,314 pounds to 18,201 pounds per year (+242%), the average yield of corn rose from 39 bushels to 153 bushels per acre (+292%), and each farmer in 2000 produced on average of 12 times as much farm output per hour worked as a farmer did in 1950.