 Frequent
Questions
- How much methane is produced by livestock?
- How will global climate change
affect agriculture?
- How can livestock methane
emissions be reduced?
- Which specific practices improve
production efficiency?
- What are some of the
other benefits associated with using improved management
practices?
Ruminant animals, such as cattle, sheep, buffalo, and goats, are
unique. Because of their special digestive systems, they can convert otherwise
unusable
plant materials into nutritious food and fiber. This same helpful
digestive system, however, produces methane, a potent greenhouse gas that
can contribute
to global climate change. Livestock production systems can also
emit other greenhouse gases such as nitrous oxide and carbon dioxide.
1. How much methane is produced by livestock?
Globally, ruminant livestock produce about 80 million metric tons of methane
annually, accounting for about 28% of global methane emissions
from human-related activities. An adult cow may be a very small
source by itself,
emitting only 80-110 kgs of methane, but with about 100 million
cattle in the U.S.
and 1.2 billion large ruminants in the world, ruminants are one
of the largest methane sources. In the U.S., cattle emit about
5.5 million metric tons of
methane per year into the atmosphere, accounting for 20% of U.S. methane emissions.
For a specific break-down of US methane sources, from
livestock to other sources visit the Methane
Sources & Emissions Web page.
2. How
will global climate change affect agriculture?
The potential effects of climate change on agriculture are uncertain, and
could be positive in some respects and negative in others. At the regional
level, changes in precipitation and temperature patterns could jeopardize
current agricultural practices. The frequency of extreme weather events
such as floods, droughts, and severe storms may increase. Sea levels could
rise, threatening vulnerable coastlines around the world, and tropical diseases
and pests that affect plants and animals could increase their range.
3. How can livestock methane emissions be reduced?
Cattle emit methane through a digestive process that is unique to ruminant
animals called enteric fermentation. Since methane represents a loss of
carbon from the rumen and therefore an unproductive use of dietary energy,
scientists have been looking for ways to suppress its production. The most
promising approach for reducing methane emissions from U.S. livestock is
by improving the productivity and efficiency of livestock production. Greater
efficiency of livestock production can increase profitability and be good
for the environment at the same time. This general approach has been demonstrated
by the U.S. dairy industry over the past several decades as milk production
increased and methane emissions decreased. Nutritional and genetic improvements
are mainly responsible for making modern U.S. dairy cows more productive.
The cow-calf sector of the beef industry is the largest emitter of methane
within U.S. livestock industries. Although efficiency gains have
also been achieved in this sector over time, there is still much room for
improvement.
Emissions from beef cows are high for a number of reasons: beef
cows are very large animals; diets, consisting mainly of forages of varying
quality,
are generally poorer than in the dairy or feedlot sectors; the
level of management is typically not as good; and the beef cow population
is very
large. Better grazing management and dietary supplementation have
been identified as the most effective ways to improve efficiency and reduce
emissions from
this sector because they improve animal nutrition and reproductive
efficiency.
4. Which specific practices improve production efficiency?
Many different management practices can improve a livestock operation’s
production efficiency and reduce greenhouse gas emissions. Some of the most
effective practices include:
- Improving grazing management
- Soil testing, followed by the addition of
proper amendments and fertilizers
- Supplementing cattle diets
with needed nutrients
- Developing a preventive herd health program
- Providing appropriate water
sources and protecting water quality
- Improving genetics and reproductive
efficiency
The particular practices a livestock producer utilizes to improve production
will depend on the circumstances of his or her operation, including the
goals to be achieved and the natural, financial, and labor resources available.
By producing meat and milk with the most efficient U.S. herd possible,
the global environment as well as our own economy will benefit. The bottom
line – improved livestock management – is good for the environment
and makes dollars and sense.
5. What are some of the other benefits
associated with using improved management practices?
Nitrous oxide emissions are produced by ruminant livestock as their manure
and urine is deposited on the soil. While more research is needed to better
quantify nitrous oxide emissions from livestock production systems and to
identify specific options for reducing emissions, efficiency improvements
can reduce nitrous oxide emissions.
Improved livestock management can also reduce atmospheric concentrations
of carbon dioxide through the mechanism of soil carbon sequestration on
grazing lands. As plants grow, they remove carbon dioxide from the atmosphere.
Even though a large portion of the plant material is harvested by grazing
cattle, through good management residues accumulate and increase the amount
of organic matter in the soil. Some of this organic matter will remain in
the soil or plant root system for long periods of time instead of being
released back into the atmosphere as carbon dioxide. More work is still
needed to develop methods for quantifying the amount of carbon sequestered
on the farm and to identify specific practices that accelerate the rate
of sequestration. |
