Life-cycle assessment of the beef cattle production system for the northern Great Plains, USA

Different assumptions about fertilization rates on pasture have resulted in a 5-fold difference in N2O emissions.

“For example, different assumptions about fertilization rates on pasture have resulted in a 5fold difference in N 2 O emissions”

Several life cycle assessment studies have concluded that grass-finished beef systems have greater greenhouse gas intensities than feedlot-finished beef systems.

“Using life cycle analysis (LCA), several studies have concluded that grass-finished beef systems have greater GHG intensities than feedlot-finished (FL) beef systems.”

The few studies that considered low rates of soil carbon sequestration in greenhouse gas accounting for beef production indicated potential emissions decreases of 24-535%.

“The few studies that considered low rates of soil C sequestration in GHG accounting for beef production indicated potential emissions decreases of 24-535%”

Tertiary emissions from manufacture of machines, equipment, and infrastructure were excluded based on their assumed minor contributions.

“Tertiary emissions, including those from manufacture of machines, equipment, and infrastructure were excluded, based on their assumed minor contributions”

Studies have identified gaps and called for more robust research and inclusion of soil carbon in future life cycle assessment models.

“Studies have identified these gaps and have called for more robust research and inclusion of soil C in future LCA models”

Adaptive multi-paddock grazed steers finished in 150 days shorter and 99 kg heavier than the continuously grazed steers in Lupo et al. (2013).

“Our AMP-grazed steers finished in 150 days shorter and 99 kg heavier than the continuously grazed steers in Lupo et al. (2013).”

Average finishing weights for the feedlot steers were similar to those reported by others.

“Average finishing weights for the FL steers (Table 2) were similar to those reported by others”

GHG emissions (per kg CW) were within the range of those reported in other studies for the Northern Great Plains, Upper Midwest, and California within the U.S.

“Generally, GHG emissions (per kg CW) were within the range of those reported in other studies for the Northern Great Plains (Lupo et al., 2013), Upper Midwest (Pelletier et al., 2010), andCalifornia (Stackhouse-Lawson et al., 2012) within the U.S.”

Application of manure produced in the FL in the present study offset 31.4% of N fertilizer application, which is lower than the 69% used in the study of Lupo et al. (2013).

“Application of manure produced in the FL in the present study offset 31.4% of N fertilizer application, which is lower than the 69% used in the study of Lupo et al. (2013).”

In beef LCA studies from the Northern Great Plains and the Upper Midwest in which soil C dynamics were estimated, hypothetical C sequestration rates of 0.41 and 0.12 Mg C ha-1 yr-1 reduced emissions from continuous grass-fed beef production by 24% and 30%, respectively.

“In beef LCA studies from the Northern Great Plains and the Upper Midwest in which soil C dynamics were estimated, hypothetical C sequestration rates of 0.41 and 0.12 Mg C ha -1 yr -1 reduced emissions from continuous grass-fed beef production by 24% and 30%, respectively (Lupo et al., 2013;Pelletier et al., 2010).”

Manure CH4 and N2O for the FL scenario estimated in this study were greater than those in other studies (Lupo et al., 2013; Pelletier et al., 2010).

“Manure CH 4 and N 2 O for the FL scenario estimated in this study were greater than those in other studies (Lupo et al., 2013;Pelletier et al., 2010).”

Feed production emissions in the FL finishing scenario were slightly greater than those reported by Lupo et al. (2013) and Pelletier et al. (2010).

“Feed production emissions in the FL finishing scenario were slightly greater than those reported by Lupo et al. (2013) and Pelletier et al. (2010), likely because our FL ration included only a small proportion of legume forages and a larger proportion of DDGS and corn grain which have greater emissions per kg than other feedstuffs (Camargo et al., 2013).”

Attempts to measure grazing-induced changes in SOC and incorporate them into LCAs have been sparse in the literature and have yielded widely variable results.

“Attempts to measure grazing-induced changes in SOC and incorporate them into LCAs have been sparse in the literature and have yielded widely variable results (Lupo et al., 2013;Mehre et al., 2024;Pelletier et al., 2010;Rowntree et al., 2020; see SI Section A.3.4 for a direct comparison with these studies).”

Grass-finished carcass weights are ∼33% lower than existing grain-finishing beef LCAs.

“Importantly, these results show that grass-finished CWs are ∼33% lower than existing grain-finishing beef LCAs (Pelletier et al., 2010b;Lupo et al., 2013;Stanley et al., 2018).”