On the contrary, there are several studies concerning CF
of cattle milk, as reviewed byPirlo (2012). In order to
harmonize the studies and make them comparable, the
International Dairy Federation (FIL-IDF, 2010) proposed a
standardization of the methodology for estimating the CF
of 1 kg of fat and protein corrected milk (FPCM). FAO
(2010)calculated that the average emission of GHG at the
farm-gate is about 2.4 kg of carbon dioxide equivalent
(CO2eq) per kg of FPCM, with wide variations depending
on the geographic area: from 1 kg of CO2eq in North
America to 7.5 kg of CO2eq in South Africa. The production
system has also a great influence on milk CF:Capper et al.
(2009)demonstrated that technological progress, occurred
between 1944 and 2007, determined a reduction from 3.66
to 1.35 kg CO2eq per kg of milk. The main driver of this
pattern is the output of milk per cow per year (Gerber
et al., 2011), that makes it possible to produce the same
amount of milk with a reduced number of cows.