The objective of this study was to quantify and compare the environmental impact, using life-cycle assessment (LCA) analysis, of four different, 4-phase growing-finishing feeding programs consisting of diets containing corn and soybean meal (CSBM), low protein CSBM supplemented with crystalline amino acids (LP), CSBM with 30% distillers dried grains with solubles (DDGS), and DDGS supplemented with crystalline Ile, Val, and Trp (DDGS+IVT). The LCA analysis was performed using an online software application (Opteinics, BASF, Lampertheim, Germany) with calculations based on environmental impact factors from the Global Feed LCA Institute feed ingredient database. The specific model included impacts of feed production, animal farming, manure management, and meat processing. Environmental impacts were calculated at the farm gate and the functional unit was 1,000 kg of carcass weight. Diet composition, growth performance, and carcass data obtained from a feeding trial were used as inputs in the LCA calculations. Using CSBM as the reference feeding program (Table 1), the LP feeding program resulted in an overall decrease in impacts associated with acidification (10.9%), water use (7.6%), and land use (9.8%), but increased impacts associated with climate change (3.3%) and fossil resource use (3.7%). Both DDGS and DDGS+IVT feeding programs increased impact on climate change (18.4-18.7%), fossil resource use (42.7-47.3%), and water use (47.2-50.0%), but decreased impacts associated with acidification (3.0-3.4%) and land use (27.2-27.3%) compared with the CSBM feeding program. Overall, the LP feeding program resulted in the lowest total environmental footprint (1.0776 person years), followed by the CSBM (1.1081 person years), DDGS+IVT (1.1845 person years), and DDGS (1.1884 person years) feeding programs.
These results indicate that feeding CSBM diets without and with crystalline amino acids have less impact on climate change, water use, fossil resource use, and total environmental footprint than DDGS feeding programs per 1000 kg of pork carcass weight.