82. Fifty Years of Progress for Beef Cattle Production in the United States.

Abstract Many changes in feed production and the maintenance and genetics of cattle have occurred over the past 50 years which affect the efficiency, productivity and environmental impacts of beef cattle production. Trends in feed and animal productivity were determined through regression of historical annual data with time. The Integrated Farm System Model, following life cycle assessment procedures, was used to assess the impact of these changes by modeling representative cattle operations throughout the US in 1972 and 2022. Improvements in yields of feed crops, animal maintenance and genetics, machinery efficiency, and the production of resources such as fuel, electricity, and fertilizer have led to many reductions in the life cycle environmental impacts of beef cattle production. Fewer but larger cattle harvested in 2022 produced 23% more beef carcass weight than in 1972. Nearly the same total feed was consumed to produce beef in 2022 as used in 1972, but about 9% less forage and 43% more grain and other concentrate feeds were fed. Increases in crop yields, particularly corn yields, led to a 12% reduction in cropland and 11% reduction in total land use over the 50-yr period. Other predicted improvements included a 25% reduction in blue water use, 23% reduction in fossil energy use, and 6% reduction in methane emissions. There was little change in total reactive N losses related to beef cattle production with a 34% increase in ammonia emissions offset by decreases in N denitrification, leaching and runoff losses. Considering the increase in animal weight produced, reductions per unit of carcass weight included 21% less feed, 29% less land, 41% less blue water, 39% less fossil energy, 26% less methane, and 19% less reactive N loss. A sensitivity analysis showed that these results were not influenced much by changes in our assumptions on past animal and pasture management. These improvements reflect the continuing trend of the U.S. beef industry to increase productivity and efficiency for a more sustainable product to meet the growing demand for beef.