Meat Eaters Guide: Methodology - Environmental Working Group

Meat Eaters Guide: Methodology
Calculation for total overall greenhouse gas emissions from beef production and consumption
c. Sources of GHG Emissions from Beef Production
In our analysis, the majority of GHG emissions from beef production come from enteric fermentation
(46 percent) and feed production (28 percent). According to our analysis, the cow-calf and steer calf
stages generate more than 65 percent of the total GHG emissions, with the remaining emissions generated
during confinement. During the cow-calf phase, the cow consumes copious amounts of hay. In
converting the hay, the cow’s body generates much higher methane emissions than with the higher
quality, lower fiber rations of the second and third stages of production. Our estimate is similar to that
of Phetteplace, et al. that 76 percent of farmgate emissions from cattle production are generated during
the first cow-calf stage. 50
The two-stage Idaho production system generated fewer production emissions than the Nebraska
system primarily due to differences in the emissions from feed production. The Idaho cow-calf system
receives the majority of its feed from grazing on federal and state ranges, previously harvested hay
ground and crop aftermath. The comparable stages in the Nebraska system are fed rations consisting
of hay (a large feed component for the cow-calf system) and grains. Both systems produce relatively
high methane from enteric fermentation due to the high-fiber diets. While the Idaho system produces
slightly more methane than the Nebraska system, the latter has higher total emissions since it both
has high enteric fermentation emissions from the high fiber hay as well as high emissions due to the
larger impact of producing the hay and grains.
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Figure 2. Sources of Beef Production Emissions: A Nebraska System
Environmental Working Group Meat Eaters Guide: Methodology 2011