Agriculture is responsible for a significant proportion
of total anthropogenic greenhouse gas
emissions (perhaps 18% globally), and therefore
has the potential to contribute to efforts to
reduce emissions as a means of minimising the
risk of dangerous climate change. The largest
contributions to emissions are attributed to ruminant
methane production and nitrous oxide from
animal waste and fertilised soils. Further, livestock,
including ruminants, are an important component
of global and Australian food production
and there is a growing demand for animal protein
sources. At the same time as governments and
the community strengthen objectives to reduce
greenhouse gas emissions, there are growing concerns
about global food security. This paper provides
an overview of a number of options for
reducing methane and nitrous oxide emissions
from ruminant production systems in Australia,
while maintaining productivity to contribute to
both objectives. Options include strategies for
feed modification, animal breeding and herd
management, rumen manipulation and animal
waste and fertiliser management. Using currently
available strategies, some reductions in emissions
can be achieved, but practical commercially
available techniques for significant reductions in
methane emissions, particularly from extensive
livestock production systems, will require greater
time and resource investment. Decreases in the
levels of emissions from these ruminant systems
(i.e., the amount of emissions per unit of product
such as meat) have already been achieved. However,
the technology has not yet been developed
for eliminating production of methane from the
rumen of cattle and sheep digesting the cellulose
and lignin-rich grasses that make up a large part
of the diet of animals grazing natural pastures,
particularly in arid and semi-arid grazing lands.
Nevertheless, the abatement that can be achieved
will contribute significantly towards reaching
greenhouse gas emissions reduction targets
