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Ruminant Livestock
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Ruminant Livestock Emissions, photo collage.Frequent Questions

  1. How much methane is produced by livestock?
  2. How will global climate change affect agriculture?
  3. How can livestock methane emissions be reduced?
  4. Which specific practices improve production efficiency?
  5. 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.

Methane Emissions From Beef and Dairy Cattle in the U.S.

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.

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