Life Cycle Assessment of the Feed Supply Chain in California Beef Productio

The environmental impacts of livestock production have most commonly been determined through the use of Life Cycle Assessment (LCA). There have been several cradle-to-farm-gate LCA for beef production around the world, but only two comprehensive cradle-to-grave LCA for beef production. The present review aims to: (1) assess beef production LCAs to date, (2) determine where variation among methodologies affect LCA outcomes, and (3) identify areas where further LCA are necessary. Twenty-two beef production LCA studies from peer-reviewed scientific journals and scientific reports were identified and analyzed, spanning a range of geographic locations and beef production systems in various parts of the world. The wide variety of LCA focusing on various areas of beef production provides a solid foundation for future beef LCA to build upon. Most common impacts included in beef LCAs are global warming, land use, energy, acidification, eutrophication, and water use. Of these categories global warming has, by far, been the impact most greatly assessed. While other categories have been addressed to some extent, methodologies for quantifying these impacts are variable and lead to a wide range of results. This warrants a need for a harmonized and standardized method for performing a complete beef LCA. The variety in type of beef system under review and methodologies used throughout the development of each LCA creates substantial variation in results. Future beef LCAs will need to further investigate the impacts of land use, energy, acidification, eutrophication, and water so that there may be a more comprehensive overview of the impacts of beef production on the environment. Currently, there is not a standard for performing a LCA in beef production though review of the literature indicates a great need. With the formation of a universal standard for performing beef LCA, it will become easier to compare production systems around the world and to identify areas where mitigation strategies are most needed in beef production.;One area where standardization can be achieved is the assessment of feeds and diets fed to cattle in beef cattle production. The United Nation's Food and Agricultural Organization (FAO) along with numerous partner entities has worked to create guidelines for quantification of the environmental performance of animal feed supply chains as a result of the Livestock Environmental Assessment and Performance (LEAP) Partnership. The goal of the present study is to determine the climate change impact from the feed supply chain associated with production of 1 kg total mixed ration (TMR) for a finisher feedlot ration typical of California, USA (kg CO2e kg-1 TMR). This was achieved following LEAP guidelines and methodology. Inventory data for a typical finisher TMR was collected. System boundaries included feed production (including crop and feed additives), transportation (from field or factory to feedmill), and feedmill compound feed production. Given the scope of the study, primary data were hardly available. 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 assumed that once a feed ingredient was transported to the feedmill, 100% of the empty return load would be allocated to the TMR production. For Scenario B and Scenario C, 50% and 0%, respectively, of the empty return load was allocated to TMR production. 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, transportation, and liquid premix production were the main contributors to the life cycle impacts of TMR production. The present study may serve as a tool for future LCA practitioners to utilize and may inform future decisions for improvements or alterations of the LEAP guidelines.