2.2. Life cycle inventory
The life cycle inventory phase requires compiling inventory data representing the material and energy inputs, outputs and emissions at each stage of the supply chain of interest. Data for each supply chain node are expressed in terms of a relevant unit of analysis.
Data for the production and processing of agricultural and animal husbandry inputs for poultry feeds were taken from recent studies by Pelletier et al. (2010a,b) of beef and pork production supply chains in the Upper Midwestern United States, and global salmon aquaculture supply chains (Pelletier et al., 2009).
Because these analyses applied the same modeling approach and assumptions,they could be directly adopted for use in the current analysis.
Data for feed milling, pullet and layer facilities, and shell egg processing and breaking operations were supplied by participating companies.
Background system data, including the production of primary energy carriers and transportation models, were derived
from the EcoInvent (2010) database and modified, where appropriate,to most closely approximate regional conditions (i.e.by using US energy sources and mixes).