As a major contributor in food production, the beef industry provides an important service to our economy that must be maintained. Production of cattle and the associated feed crops required also impact our environment, and this impact is not well understood. A report from the Food and Agriculture Organization noted that worldwide, animal agriculture contributed 18% of global greenhouse gas emissions, greater than all transportation. An analysis conducted by the U.S. Environmental Protection Agency estimated that animal agriculture contributed 3.8% of the total greenhouse gas emission in the U.S. with transportation being about six times this amount. A number of studies have determined a carbon footprint of beef production with most values ranging from 10 to 15 lb CO2e/lb body weight (BW) produced. Although most of the attention in recent years has been given to carbon footprint, there are other environmental impacts that must be considered. These include fossil energy use, water use, and reactive nitrogen loss to the environment.
The stated objectives for this work were to further our understanding of the environmental impacts of beef production in the U.S.by determining environmental footprints of current and historical beef cattle production systems in the Midwestern U.S. To accomplish this objective, extensive data from the beef and farming production systems at the Roman L. Hruska U.S. Meat Animal Research Center (MARC) were used to enable a comprehensive evaluation. Specific objectives were to determine the carbon, energy, water and reactive nitrogen footprints of the current production system and to compare these current footprints to those of the production systems used in 1970 and 2005 to quantify improvements made through time.
The beef production system used at MARC was simulated through time using the Integrated Farm System Model (IFSM). The MARC system was modeled as four components: the crop farm, the spring cow calf operation, the fall cow calf operation, and the feedlot. Production and economic information for 2011 was used to set model parameters for each of the four components. The accuracy of the simulated system was evaluated by comparing predicted feed production and use, energy use, and production costs to actual records from MARC for 2011. Twenty-five year simulations were then performed to determine the long term carbon, energy, water, and reactive nitrogen footprints of the beef produced using current practices and those used in 1970 and 2005. The year 1970 was selected to illustrate the production practices used 40 years ago and 2005 was used to capture the effect of including distiller’s grain in cattle diets.
Model simulated predictions for weather year 2011 were within 1% of actual records for feed production and use, energy use, and production costs, suggesting that the IFSM accurately represented the beef system at MARC. A 25-year simulation of the current production system of MARC gave a carbon footprint of 10.9 lb of CO 2 equivalent units per lb BW sold, and the energy required to produce that beef (energy footprint) was 11,400 Btu/lb BW. The total water required (water footprint) was 2,560 gallon/lb BW, and the water footprint excluding that obtained through precipitation was 335 gallon/lb BW. The simulated total cost of producing this beef was $0.96/lb BW sold, which agreed with their production records. Simulation of the production practices of 2005 indicate that use of distiller’s grain in animal diets has had a relatively small negative impact on environmental footprints except that reactive nitrogen loss has increased 10%. Compared to 1970, the carbon footprint of the beef produced has decreased 6% with no change in the energy footprint and a 3% reduction in the reactive nitrogen footprint. The water footprint, excluding precipitation, has increased 42% due to greater use of irrigated corn production. These results support that progress has been made in reducing some of the environmental impacts of beef production at MARC.
This work furthers our understanding of the impact of beef cattle production on our environment. Although the production system at MARC is similar to that of commercial beef producers, these results do not necessarily represent the industry as a whole. Beef cattle are produced in the U.S. over a wide range of climates and soil types. The beef industry also uses calves and cull cattle from the dairy industry for beef production. These and other alternative production practices used throughout the industry influence the environmental impact of the beef produced. To better represent the whole of U.S. beef production, further analysis is needed covering all regions and the important production practices across the country.