(Table 5). Greenhouse gases
were primarily emitted from the cow–calf phase, due
to the breeding stock living on the land for a full year to
produce a calf and the increased enteric emission from
these cattle consuming a high-forage diet (Table 5). In
this analysis, CO2 emission came through the burning
of fossil fuels and the use of lime on crop and pasture
land. Not much lime is used in this region, but that
used contributed 66% of the CO
2 emission associated
with the cow–calf phase. Methane and N2O emissions
also primarily came from the cow–calf phase where
73% of the CH
4 and 66% of the N2O were emitted.
The total carbon footprint of this production system, including prechain sources, was 20.2 kg CO2e/kg
CW (Table 5), which is similar to values found in other
studies. In a previous summary of 7 farm-gate LCA of
beef cattle production (Rotz et al., 2013), reported carbon
footprints ranged from 9.7 to 19.2 kg CO2e/kg BW (about
17 to 31 kg CO2e/kg CW) with an average around 13 kg
CO
2e/kg BW (21 kg CO2e/kg CW). Of this total, 67%
of the footprint was associated with the cow–calf phase,
which is also consistent with previous LCA. Total fossil
energy input was 52 MJ/kg CW with 50% used in the
cow–calf phase and 26% used in the feedyard. This was
similar to that found previously for a production system
in Nebraska (Rotz et al., 2013). Nonprecipitation water
use primarily occurred through irrigation of feed crops
fed in feedyards. The total was 1,913 L/kg CW with 57%
associated with the finish operation. Total reactive N loss
was 122 g N/kg CW with 53% lost from the cow–calf
phase and 31% lost from the finishing phase (Table 5).
This was 18% less than that found by Rotz et al. (2013)
due to less fertilizer use in this region. No other studies
were available for comparison.