Shortages in beef fat supply combined with advances by Boyce and Sabatier in the hydrogenation of plant materials soon accelerated the use of Bradley's method, and between 1900 and 1920 commercial oleomargarine was produced from a combination of animal fats and hardened and unhardened vegetable oils. The economic depression of the 1930s, followed by rationing in America and the United Kingdom, among other countries, during World War II, led to a reduction in supply of animal fat and butter, and, by 1945, "original" margarine had almost completely disappeared from the market. In the United States, problems with supply, coupled with changes in legislation, caused manufacturers to switch almost completely to vegetable oils and fats (oleomargarine) by 1950, and the industry was ready for an era of product development.