The Agency is assisting Member States to reduce the amount of methane produced by ruminant livestock

Over the past 300 years, atmospheric methane concentrations have increased by approximately 2.5 times those of the pre-industrialization era. Atmospheric methane concentrations increased by 10.8 ppb/year in samples collected between 1979 and 1999. This elevation has been attributed to the expansion in agricultural and industrial activities, including livestock farming, rice cultivation, mining of fossil fuels, reticulation of natural gas, and large-scale burning of forest and grassland biomass.

The Agency is assisting Member States to reduce the amount of methane produced by ruminant livestock Increasing methane concentrations in the atmosphere have been identified as the second largest contributor to global warming after carbon dioxide. Thus, methane was included in the Kyoto Protocol with 1990 chosen as the base year for future decisions concerning the impact of mitigation strategies. However, the concentration of atmospheric methane has only increased 0.3 ppb/year since 1999 and presently, the level of methane emissions is equivalent to the removals of atmospheric concentrations.

The world population of ruminant livestock, in cattle equivalents, has steadily increased in the last 30 years despite a nearly 15% drop of sheep population in the 1990’s as a result of the downturn of the wool industry. However, from 1979 to 1999 the population of ruminant livestock increased at the rate of 9 million head per year and is currently 11 million head per year since 1999 (see figure). In the global balance of methane production, ruminant livestock account for 15.7% of global and 25.7% of anthropogenic methane production.

The Agency is assisting Member States to reduce the amount of methane produced by ruminant livestock Methane is produced from a variety of sources - both human-related (anthropogenic) and natural. Human-related activities which accounts for more than 60% of global methane emissions include fossil fuel production, animal husbandry (enteric fermentation in livestock and manure management), rice cultivation, biomass burning, and waste management. Natural sources include wetlands, gas hydrates, permafrost, termites, oceans, freshwater bodies, non-wetland soils, and other sources such as wildfires.

The Kyoto agreement and its subsequent outcomes placed significant pressure on the ruminant livestock industry to reduce the amount of methane produced. Despite world-wide research efforts there are no profitable solutions in place that can be adopted by farmers for suppressing methane production for a given diet; nevertheless, it became quite clear that increasing the quality of the diet decreases the amount of methane produced per unit of product thus increasing the efficiency of production. In other words, animals fed better quality diets produce less methane than those fed more fibrous diets. Therefore, more efficient feeding systems using better quality feeds will not only result in higher profitability for the farmer but less atmospheric pollution.

Take home message

  • - The Intergovernmental Panel on Climate Change (IPCC) acknowledged in 2007 that methane concentrations in the atmosphere have reached a high level plateau, i.e. emissions equal removals.
  • - Ruminant livestock population (cattle equivalents) shows a continuous and even higher rate of increase.
  • - Currently there is no relationship between increasing ruminant animal population and changes in atmospheric methane concentrations.
  • - Improvements in animal husbandry and feeding practices in developing countries may have contributed in lowering the impact of livestock ruminants on atmospheric methane concentrations.

The relative reduction in enteric methane production in the last 10 years has been probably due to improvements in animal husbandry and feeding practices, especially in developing countries. The increasing demand for animal products for human consumption has directed research, technology transfer and developmental work in favor of more integrated and efficient production systems including better feeding strategies using better quality feeds, resulting in the bonus side-effect of lower methane production per unit of product.

The Agency is assisting Member States to reduce the amount of methane produced by ruminant livestock Reducing enteric methanogenesis is beneficial from the standpoint of increasing energy efficiency of the animal and from an environmental perspective. Methane production in ruminants is negatively correlated with energy utilization and it can range from 2 to 12% of the gross energy intake. Reduction of methane production can be achieved by use of feed additives e.g. ionophores, probiotics, acetiogens, bacteriocins, essential oils, grains, and high-quality forages. However, it is also important to ensure that the additives do not adversely affect animal productivity.

The IAEA through the Animal Production and Health Section has strongly supported research and developmental work in developing countries in the last 30 years for improving quality and availability of local feeds and in the formulation of improved quality rations.

The Agency is assisting Member States to reduce the amount of methane produced by ruminant livestock As an example, a recent Coordinated Research Project on “Development and use of rumen molecular techniques for predicting and enhancing productivity” screened more than 200 plants and plant extracts comprising of browse, multi-purpose trees, medicinal plants, and spices from Asia, Africa and Latin America. The results indicated that Acacia angustissima, Allium sativum, Canabis indica, Emblica Jambolana, E. officinalis, Eucalyptus globulus, Foeniculum vulgare, Mangifera indica, Mentha pipperita, Populus deltoides, Psidium guajava, Quercus incana, Sesbania sesban, Syzygium aromaticum, Terminalia belerica, Terminalia chebula, and Trachyspermum ammi inhibited methane production by 25 to 100% and a large number of plants were also inhibitory for rumen ciliate protozoa. Methane production was reduced in vitro by between 10 and 100% and in vivo by 11 to 35%.

Actions taken by the IAEA through these projects have resulted in improved productivity of livestock, and are also contributing to reducing the impact of ruminants on the environment.