A life cycle assessment of a beef feedlot finishing ration supply chain in California

Abstract Text: A life cycle assessment (LCA) was conducted for the feed supply chain (FSC) of a total mixed ration (TMR) typical of finishing feedlot cattle produced in California, USA. The goal was to determine the global warming potential (kg CO₂e kg^-1 TMR) associated with the FSC along with the associated impacts of the FSC on the total life cycle of feedlot cattle produced in California. The methodology used followed the Livestock Environmental Assessment and Performance (LEAP) Partnership guidelines for FSC. System boundaries included feed production (crops and feed additives), transportation (from field or factory to feedmill), and TMR compound feed production (i.e. at the feedmill). Life cycle inventory data for a typical finishing TMR was collected. Given the scope of the study, primary data were limited. In accordance with LEAP guidelines, secondary data were sourced from national databases and Ecoinvent^TM unit process data. Three scenarios were assessed as a result of allocation at the transportation step. Scenario A, B, and C assumed that once a feed ingredient was transported to the feedmill, 100%, 50%, and 0% of the empty return load would be allocated to TMR production, respectively. Additionally, the impacts of feed production in relation to the entire feedlot cattle production life cycle, for Scenario A, was determined. Total GHG emissions were determined to be 0.630 kg CO₂e/ kg TMR for Scenario A, 0.576 kg CO₂e/ kg TMR for Scenario B, and 0.521 kg CO₂e/ kg TMR for Scenario C. Corn production, feed transportation, and liquid premix production were the main contributors to the life cycle impacts of the TMR. When assessing the entire feedlot life cycle for Scenario A, total GHG emissions were determined to be 0.824 CO₂e/ kg TMR. Additionally, for scenario A, feed production in the Angus and Holstein feedlot scenarios was found to contribute approximately 76% and 58% of total feedlot emissions, respectively. The FSC is a major contributor of emissions to the total life cycle of feedlot cattle production and knowledge thereof is a first step in improving efficiencies and reducing emissions.

Keywords: Feedmill, Greenhouse Gas, Sustainability