footprint to 51.2 ± 4.8 MJ/kg CW for the same reasons
as those for the carbon footprint.
Nonprecipitation water use varied widely from 976
to 7,630 L/kg CW across the production systems, influenced
primarily by the amount of irrigation used to produce
feed crops (Table 6). The weighted mean (2,575 ±
475 L/kg CW) was 18% greater than the mean because
more irrigation was used for feed production in Texas and
in the western side of the region where most of the cattle
were finished. Inclusion of Holstein steers increased the
water use per unit of CW because these cattle spent more
time on feedyards consuming feed from irrigated crops.
With the inclusion of cull dairy cows, water use dropped
to 2,470 ± 455 L/kg CW because some of their water use
was allocated to milk production.
Reactive N loss also had a wide range due primarily
to the influences of climate (Table 6). Runoff
and leaching of N was greater in the eastern side of
the region due to more rainfall. In the western side, N
loss was minimal except for NH3 volatilization. The
weighted mean for the region (135 ± 11 g N/kg CW)
was similar to the mean. Including Holstein steers had
little effect, and including Holstein cows gave a slight
increase due to greater N losses from more intensively
managed dairy operations.
Sensitivity Analysis
Major components of the carbon footprint of beef
cattle production include enteric CH4 emission, CH4
and N2O emission from manure, N2O emission from
pasture and cropland, CO2 from fuel combustion and
lime use, and prechain emissions during the manufacture
of resources used. The regional footprint was
moderately sensitive to enteric CH4, slightly sensitive