Agriculture Reference
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assessments (LCA) that compared organic and non-organic dairy systems in
Scandinavia [29] and in the Netherlands [94] also identified advantages in
organic dairy production. Lynch et al. [95] noted the scarcity of US and Cana-
dian data for GHG emissions associated with dairy systems. A US comparison
of organic, non-organic, and non-organic plus recombinant bovine somato-
tropin (rbST) dairy production, which included the GHG value of measured
inputs, outputs and land area, concluded that organic systems had the highest
environmental impact [96]. However, this study focused on the efficiency of
production per cow and was neither a whole-farm study nor a LCA; therefore,
the implications of related factors, such as culling rate, were not considered.
Even the LCA and whole-farm modeling studies did not include the economic
or social values of these systems or their ecosystem services.
According to a Food and Agriculture Organization LCA of the dairy
sector, US milk production represents about 16% of the world total, while
the relative contribution of the GHG emissions, per kg of fat- and protein-
corrected milk (FPCM), associated with milk production, processing and
transportation in the US, is about 8% of the world total. This ratio of GHG
emissions to milk production is the lowest of any global region, including
western Europe [97] (Figure 4.2). Within this highly effi cient US dairy
sector, organic accounts for only about 4% of production [98], but organic
dairy sales have continued to increase by double digits, even during the
Great Recession that began in 2008 [99].
4.5.2 GREENHOUSE GAS EMISSIONS IN BEEF SYSTEMS
While the per-head carbon footprint of grain-finished cattle was higher
as estimated by Peters et al. [100] in an Australian study, it was offset by
high feedlot rates of gain. However, the contribution of legumes in pas-
tures was not determined in that study, and in a review of greenhouse gas
emissions from beef and dairy cattle production systems, no reference was
made to forage legumes [101]. There is an opportunity to reassess these
beef LCA incorporating MiG and high-quality forages that can greatly
increase the rate of gain of cattle finished on pasture. Evidence for this
comes from studies of plants used for biofuel production. Kim and Dale
[102] reported that alfalfa, a perennial, N-fixing legume, resulted in the
 
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