Agriculture Reference
In-Depth Information
dairying system in New Zealand and concluded
that there is potential to decrease GHG inten-
sity of milk production by up to 34%. This
could be achieved through a combination of
strategies: improvements in reproductive per-
formance leading to less culling, use of high
genetic merit cows, and better pasture manage-
ment to permit lower stocking rates and less N
fertilizer use. Haas
et al
. (2001) explored grass-
land dairy systems in Germany and concluded
that extensive systems had a lower GHG inten-
sity than intensive or organic farming systems.
The extensive farms used lower stocking rates,
less N fertilizer and produced less milk per cow
than the intensive farms. In a study of pastoral
dairy systems, O'Brien
et al
. (2010) evaluated
three divergent lines of Holstein Friesian cows
(i.e. high production North American, high
durability North American and New Zealand
line) in three feeding systems (i.e. high grass
allowance, high stocking rate and high concen-
trate supplementation). The most profitable
combination was the New Zealand line in the
high stocking rate system. This combination
also resulted in a 6% reduction GHG intensity
of milk (cradle to farm-gate), demonstrating
that well managed grass-based dairy produc-
tion systems can achieve high profitability and
low GHG emissions.
Herd Health and
Animal Management
The health challenges of modern dairy pro-
duction not only affect farm profitability, but
increase GHG intensity of milk production
because the quantity of milk shipped from the
farm decreases, yet emissions remain unchanged.
Mastitis, metabolic diseases, lameness, transition
cow management, grouping strategies and calf
management have been identified as potential
improvement areas in intensive dairying that
would lead to lower GHG intensity of milk
production (Place and Mitloehner, 2010).
Greenhouse Gas Intensity
of Beef Production
Beef production systems are often very complex,
which can be challenging in terms of establishing
the system boundary for a LCA. Beef production
is typically comprised of farms that produce
calves (cow-calf farms) and farms that grow and
fatten calves for market. Sometimes the entire
process occurs within a single farm, but more
often a series of farms is involved with calves mov-
ing from farm to farm. The system also typically
incorporates varying degrees of grazing and
confinement. Many farm-based LCAs of GHG
emissions from beef production systems have
been published in recent years (Subak, 1999;
Phetteplace
et al
., 2001; Cederberg and Stadig,
2003; Johnson
et al
., 2003; Ogino
et al
., 2004,
2007; Casey and Holden, 2006a, b; Williams
et al
., 2006; Stewart
et al
., 2009; Beauchemin
et al
.,
2010, 2011; Crosson
et al
., 2010; Nguyen
et al
.,
2010; Pelletier
et al
., 2010; Peters
et al
., 2010;
Veysset
et al
., 2010; White
et al
., 2010; Foley
et al
., 2011) with most of the ones published by
2010 summarized recently (Crosson
et al
.,
2011). LCAs that consider the entire beef produc-
tion system (i.e. including the breeding stock
and growth/fattening of the progeny) report a
GHG intensity ranging from 10 to 17 kg CO
2
e
kg
−1
live weight (14-37 CO
2
e kg
−1
of carcass
weight). The lower intensity estimates are for
intensive beef production systems used in North
America (Johnson
et al
., 2003; Beauchemin
et al
,
2010; Pelletier
et al
., 2010) and parts of Europe
(Casey and Holden, 2006b; Crosson
et al
., 2010;
Reproductive Performance
Modern high-producing dairy cows are consid-
ered sub-fertile, as characterized by low preg-
nancy rates and high rates of embryonic
mortality, and this situation has a major impact
on the GHG intensity of milk production
(Garnsworthy, 2004). About a quarter of the
emissions are from replacement heifers in
intensive dairy operations (McGeough
et al
.,
2012), so it follows that improvement in cow
fertility and a resulting decrease in the number
of replacements needed to maintain herd size
for a given level of milk production would
decrease the GHG intensity of milk production.
Garnsworthy (2004) showed for an intensive
UK dairy system that total enteric CH
4
emis-
sions from replacements could be reduced by
24% by improving fertility to an ideal level
through improved oestrous and conception
rate of cows.
