A simulation-based approach for evaluating and comparing the environmental footprints of beef production systems1

Abstract

A methodology was developed and used to determine environmental footprints of beef cattle produced at the U.S. Meat Animal Research Center (MARC) in Clay Center, NE, with the goal of quantifying improvements achieved over the past 40 yr. Information for MARC operations was gathered and used to establish parameters representing their production system with the Integrated Farm System Model. The MARC farm, cow-calf, and feedlot operations were each simulated over recent historical weather to evaluate performance, environmental impact, and economics. The current farm operation included 841 ha of alfalfa and 1,160 ha of corn to produce feed predominately for the beef herd of 5,500 cows, 1,180 replacement cattle, and 3,724 cattle finished per year. Spring and fall cow-calf herds were fed on 9,713 ha of pastureland supplemented through the winter with hay and silage produced by the farm operation. Feedlot cattle were backgrounded for 3 mo on hay and silage with some grain and finished over 7 mo on a diet high in corn and wet distillers grain. For weather year 2011, simulated feed production and use, energy use, and production costs were within 1% of actual records. A 25-yr simulation of their current production system gave an average annual carbon footprint of 10.9±0.6 kg of CO2 equivalent units per kg BW sold, and the energy required to produce that beef (energy footprint) was 26.5±4.5 MJ/kg BW. The annual water required (water footprint) was 21,300±5,600 L/kg BW sold, and the water footprint excluding precipitation was 2,790±910 L/kg BW. The simulated annual cost of producing their beef was US$2.11±0.05/kg BW. Simulation of the production practices of 2005 indicated that the inclusion of distillers grain in animal diets has had a relatively small effect 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, a 3% reduction in the reactive nitrogen footprint, and a 6% reduction in the real cost of production. The water footprint, excluding precipitation, has increased 42% due to greater use of irrigated corn production. This proven methodology provides a means for developing the production data needed to support regional and national full life cycle assessments of the sustainability of beef.

Management characteristics of beef cattle production in the Northern Plains and Midwest regions of the United States

“…The country has been divided into 7 cattle producing regions according to climate and other regional differences. The data gathered are used to form representative operations within each region to develop farm gate partial LCA using a methodology developed by Rotz et al (2013). Additionally, the production data are combined with information gathered from packing, marketing, and consumer segments of the beef value chain to complete a cradle-to-grave LCA (Stackhouse-Lawson et al, 2013).…”

Mitigation of greenhouse gas emissions from animal production

“…These production systems include either three phases (cow‐calf to stocker to feedlot) or two phases (cow‐calf to feedlot). Existing studies agreed that the cow‐calf phase contributed 67% to 72% of the CF for the overall beef production system . The cow‐calf phase requires the maintenance of the large number of breeding animals to produce the calves .…”

“…A simulation of changes in beef production practices and their effect on CF estimated that the CF of beef cattle decreased 6% from 1970 to 2005, primarily due to improvement in crop productivity; however, the CF remained stable from 2005 to 2011, indicating that the negative effect of feeding of distillers grain on CF had offset the small improvement obtained through genetic improvement of corn yield …”

“…Most existing beef LCA studies followed a 'cradle to farm-gate' approach and they reported CFs of feedlot finished beef production in the USA in the range of 14 to 27 CO 2 e per kg carcass weight. [24][25][26][27][28][29][30] The variations in CF among studies were mainly due to differences in finishing weight and time spent in the feedlot, types and amount of feed, manure handling practices, region variability, and methods used. These production systems include either three phases (cow-calf to stocker to feedlot) or two phases (cow-calf to feedlot).…”

“…Existing studies agreed that the cow-calf phase contributed 67% to 72% of the CF for the overall beef production system. 25,[28][29][30] The cow-calf phase requires the maintenance of the large number of breeding animals to produce the calves. 25 Breeding animals may live on the land for a full year to produce a calf, and was responsible for the majority of the CF.…”