Environmental Assessment of a Representative Grass-finished Beef Operation in Southern Pennsylvania

Abstract Text:  The objective of this study was to quantify environmental impacts of a representative grass-finished beef operation in southeastern Pennsylvania. A farm-gate life cycle assessment was conducted using the Integrated Farm System Model to estimate greenhouse gas emissions, reactive nitrogen loss, and water and energy use. Parameters describing the operation were obtained from published survey results of pasture finishing beef producers in the northeastern United States. Cattle were rotationally grazed on 101 ha of perennial cool season grass-legume mixed pasture. Supplementation included silage and dry hay produced on the farm. Alfalfa silage was purchased for winter feeding and the final finishing phase. Net forage production was 652 t DM. The Angus herd consisted of 80 cows, 12 replacement heifers, 60 stockers, and 59 finishing cattle on a spring calving cycle. Calf weaning weight and average mature cow weight were 182 kg and 454 kg, respectively. Cattle were finished at 21 mo of age on high quality pasture and silage, with an ADG of 0.9 kg/d and shrunk body weight (SBW = 96% of live weight) of 477 kg. Simulation results over 25-years of historical weather for Lancaster, PA were sensitive to pasture management. When pastures were limed, average annual carbon footprint was 14.4 ± 0.5 kg CO₂e/kg SBW sold, requiring 27.3 ± 1.9 MJ of energy/kg SBW sold. When lime was not applied to pastures, the average annual carbon footprint was 12.6 ± 0.4 kg CO₂e/kg SBW, requiring 12.6 ± 0.7 MJ of energy/kg SBW. Total water use (water footprint) for both scenarios was 13,900 ± 1,350 L H₂O/kg SBW, and the water footprint excluding rainfall was 41 ± 2 L H₂O/kg SBW. The reactive nitrogen footprint was 91.0 ± 29.5 g reactive N loss/kg SBW. Generating data related to the environmental impacts of grass finished beef production provides a baseline for management decisions intended to improve the sustainability of production systems.

Keywords:  grassfed beef, environment, carbon footprint