|Rotz, Clarence - Al|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2012
Publication Date: 9/5/2012
Citation: Stackhouse-Lawson, K.R., Rotz, C.A., Oltjen, J.W., Mitloehner, F.M. 2012. Growth-promoting technologies decrease the carbon footprint, ammonia emissions, and costs of California beef production systems. Journal of Animal Science. 90:4656-4665. Interpretive Summary: Development of effective mitigation strategies for reducing greenhouse gas (GHG) and ammonia emissions from beef production systems is increasing in priority upon public, industry, and political agendas. Improving animal productivity is believed to be an effective emission mitigation tool; however, few studies have evaluated net emission reductions over full beef production systems. To conduct such an anlaysis, a life cycle assessment approach is required. Primary and secondary GHG emissions and ammonia emissions from the various phases of beef production in California were quantified using whole-farm simulations. Treatments using growth promoting technologies were evaluated to determine the environmental and economic benefits of their use. Growth promoting technologies effectively reduced the carbon footprint by 7 to 10% with up to a 9% reduction in ammonia emission from the full production system. These treatments increased production costs, but the increased meat production offset these costs, reducing the cost per unit of meat produced. Application of growth promoting technologies is a cost effective way to mitigate GHG and ammonia emissions from beef cattle production. The carbon footprint reduction obtained over the full production system is relatively small; however, because the major portion of the GHG emissions occurs during the cow calf phase before these treatments are applied.
Technical Abstract: Improved animal performance is suggested as one of the most effective mitigation strategies to reduce greenhouse gas (GHG) and ammonia (NH3) emissions from livestock production per unit of product produced. However, little information exists on the effects of increased animal productivity on the net emission reduction 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 that utilize management technologies to enhance animal performance. The IFSM is a farm process model that simulates crop growth, feed production, animal performance, and manure production and handling through time to predict the performance, economics, and environmental impact of production systems. Simulated beef production systems included (1) Angus-natural with no application of growth enhancing technologies, (2) Angus-implant with ionophore and growth implant application, (3) Angus-beta2-adrenergic agonists (BAA) with ionophore, growth implant, and BAA application, (4) Holstein-implant with growth implant and ionophore application, and (5) Holstein-BAA with ionophore, growth implant, and BAA application. Ammonia emissions ranged from 91 to 138 g/kg hot carcass weight(HCW). During the feedlot phase, ammonia was reduced using the BAA treatment by 6 to 7 g/kg HCW which resulted in a 7% net NH3 reduction from the total production system. The carbon footprint for the Angus and Holstein systems ranged from 22.0 to 24.5 and 10.3 to 10.8 kg CO2e/kg HCW, respectively. The carbon footprint was reduced by 7 to 11% in response to improved animal performance with application of ionophore, growth implant, and BAA. Application of growth promoting technologies is a cost effective way to mitigate GHG and NH3 emissions from conventionally managed cattle, but naturally managed cattle can bring a similar net return when sold at a 7% greater premium price. Treatment with these growth promoting technologies effectively reduced the carbon footprint by 2.5 kg CO2e/kg HCW and NH3 emissions by 8 g/kg HCW from the beef production systems. However, the carbon footprint reduction obtained over the full production system was relatively small, because the major portion of the GHG emissions occurred during the cow calf phase before these treatments were applied.