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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGING FARMS FOR ENVIRONMENTAL STEWARDSHIP AND PROFIT

Location: Pasture Systems & Watershed Management Research

Title: Carbon footprint and ammonia emissions of California beef production systems

Authors
item Stackhouse, K -
item Rotz, Clarence
item Oltjen, J -
item Mitloehner, F -

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 19, 2012
Publication Date: September 5, 2012
Citation: Stackhouse-Lawson, K.R., Rotz, C.A., Oltjen, J.W., Mitloehner, F.M. 2012. Carbon footprint and ammonia emissions of California beef production systems. Journal of Animal Science. 90:4641-4655.

Interpretive Summary: Beef production is a recognized source of greenhouse gas (GHG) and ammonia (NH3) emissions; however, little information exists on the net emissions from beef production systems. A partial life cycle assessment (LCA) was conducted using the Integrated Farm System Model (IFSM) to estimate GHG and NH3 emissions from representative beef production systems in California. The IFSM is a farm process model that simulates crop growth, feed production and use, animal growth, and the return of manure nutrients back to the land to predict the environmental impacts and economics of production systems. An evaluation of differing production management strategies resulted in ammonia emissions ranging from 98 +/- 13 to 138 +/- 16 g/kg hot carcass weight (HCW) and carbon footprints of 10.8+/- 1.4 to 22.9 +/- 2.0 kg CO2e/kg HCW. Within the British beef production cycle, the cow-calf phase was responsible for 69 to 73% of total GHG emissions with 17 to 27% from feedlot sources. Holstein steers that entered the beef production system as a by-product of dairy production had the lowest carbon footprint because the emissions associated with their mothers were primarily attributed to milk rather than meat production. For the Holstein system, the feedlot phase was responsible for 92% of the total GHG emission, while the calf-ranch phase was responsible for 6% with the remaining 2% from transportation. This simulation study provides baseline emissions data for California beef production systems and indicates where mitigation strategies can be most effective in reducing emissions.

Technical Abstract: Beef production is a recognized source of greenhouse gas (GHG) and ammonia (NH3) emissions; however, little information exists on the net emissions from beef production systems. A partial life cycle assessment (LCA) was conducted using the Integrated Farm System Model (IFSM) to estimate GHG and NH3 emissions from representative beef production systems in California. The IFSM is a farm process model that simulates crop growth, feed production and use, animal growth, and the return of manure nutrients back to the land to predict the environmental impacts and economics of production systems. Ammonia emissions are determined by summing the emissions from animal housing facilities, manure storage, field applied manure, and direct deposits of manure on pasture and rangeland. All important sources and sinks of methane, nitrous oxide, and carbon dioxide are predicted from primary and secondary emission sources. Primary sources include enteric fermentation, manure, cropland used in feed production, and fuel combustion. Secondary emissions occur during the production of resources used on the farm, which include fuel, electricity, machinery, fertilizer, and purchased animals. The carbon footprint is the net exchange of all GHG in carbon dioxide equivalent (CO2e) units per kg of hot carcass weight (HCW) produced. Simulated beef production systems included cow-calf, stocker, and feedlot phases for the traditional British beef breeds and calf ranch and feedlot phases for Holstein steers. An evaluation of differing production management strategies resulted in ammonia emissions ranging from 98+/-13 to 138+/-16 g/kg HCW and carbon footprints of 10.8+/-1.4 to 22.9+/-2.0 kg CO2e/kg HCW. Within the British beef production cycle, the cow-calf phase was responsible for 69 to 73% of total GHG emissions with 17 to 27% from feedlot sources. Holstein steers that entered the beef production system as a by-product of dairy production had the lowest carbon footprint because the emissions associated with their mothers were primarily attributed to milk rather than meat production. For the Holstein system, the feedlot phase was responsible for 92% of the total GHG emission, while the calf-ranch phase was responsible for 6% with the remaining 2% from transportation. This simulation study provides baseline emissions data for California beef production systems and indicates where mitigation strategies can be most effective in reducing emissions.

Last Modified: 4/19/2014
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