96 - Assessing the Sustainability of Multiple Grass-fed and Grain-fed Beef Production Systems

Increased demand for grass-fed beef raises many producers' and consumers' concerns regarding product quality, economic viability, and environmental impacts that have gone unanswered. Therefore, using a holistic approach, we investigated the performance, carcass quality, financial outcomes, and environmental impacts of four typical grass-fed and conventional beef systems raised in a Mediterranean climate in the western United States. The treatments included: 1) steers stocked on pasture and feedyard finished for 128 days (CON); 2) steers grass-fed for 20 months (GF20); 3) steers grass-fed for 20 months with a 45-day grain finish (GR45); and 4) steers grass-fed for 25 months (GF25). The data were analyzed using a mixed model procedure in R. Data from these beef production systems, a weaning-to-harvest life cycle assessment (LCA) using the SPARKS-LCA model framework, to determine global warming potential (GWP), consumable water usage, energy, smog, and land use footprints. Final body weight varied significantly between treatments (P < 0.001) with CON finishing at 632 kg, followed by GF25 at 570 kg, GR45 at 551 kg, and GF20 478 kg. Dressing percentage differed significantly between all treatments (P < 0.001) with CON at 61.8%, followed by GR45 at 57.5%, GF25 at 53.4%, and GF20 at 50.3%. Breakeven costs with harvesting and marketing for the CON, GF20, GR45, and GF25 were $6.01, $8.98, $8.02, and $8.33 per kg hot carcass weight (HCW), respectively. The GWP for the CON, GF20, GR45, and GF25 were 4.79, 6.74, 6.65 and 8.31 CO₂e/kg HCW, respectively. Water consumptive use for CON, GF20, GR45, and GF25 were 933, 465, 678 and 1245 L /kg HCW, respectively. Energy use for CON, GF20, GR45, and GF25 were 18.69, 7.65, 13.84 and 8.85 MJ /kg HCW, respectively. The results from this study indicate that differences in grass-fed beef management can have profound impacts on food security and sustainability.