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New studies provide the first accurate estimates of greenhouse gas emissions from East African livestock

ILRI scientist John Goopy describes ILRI’s Mazingira Centre research on livestock and greenhouse gas emissions to ILRI partners at the CGIAR Research Program on Climate Change, Agriculture and Food Security and leads them on a tour of Mazingira’s Greenhouse Gas Laboratory, in Nairobi, Kenya (photo credit: CCAFS/S Kilungu).

The following excerpts are from an article ILRI scientist John Goopy published in late May 2018 reporting on the results of two recent studies that provide more accurate estimates of the greenhouse gases emitted by East African smallholder livestock systems.

‘. . . Presently estimates of GHGs from African livestock systems mainly rely on default protocols (TIER I) developed by the Intergovernmental Panel on Climate Change (IPCC). These use data from livestock systems in Europe and the US (themselves over 20 years old) combined with expert opinion. The IPCC itself stresses the desirability of more accurate assessment of important sectors or key categories, i.e. sources or sinks of GHGs which significant influence a country’s total inventory of greenhouse gases in terms of the absolute level, the trend, or the uncertainty in emissions and removal, and provides guidelines for deriving better estimates of GHGs (TIER II).

‘Unfortunately, uncertainty about the accuracy of TIER I estimates is compounded by the difficulty of getting newer more accurate data for TIER II—African farmers typically do not keep the sort of formal records that would be used to derive better GHG estimates. A further problem is that some important assumptions used in creating TIER II estimates may not apply in parts of Africa.

‘TIER I estimates, as well as current TIER II guidelines, assume that animals have unrestricted access to feed and that they either gain weight or that their weight is unchanging. Most agriculture in Africa is rain-fed and seasonal, which tends to impact on feed availability for livestock. Thus for parts of the year animals may be losing weight. Because feed intake is the biggest driver of methane production and because ruminants use body reserves with a higher efficiency than ingested feed, seasonality of feed supply has important implications for the estimation of ruminant methane production throughout the year.

Considering the potential importance of fluctuations in feed availability (and quality) on estimates of enteric CH4 emissions, researchers from the Mazingira Centre* at the International Livestock Research Centre (based in Nairobi, Kenya), developed a different approach that would allow us to produce emission estimates by making measurements to determine energy expenditure and thus feed intake, without the need to rely on assumptions of unlimited feed availability.

We recently completed two studies using this novel methodology to derive more accurate GHG estimates for smallholder livestock systems in East Africa. . . .

These studies have highlighted substantial discrepancies between TIER I and TIER II emission estimates in African livestock systems and also demonstrated the great heterogeneity of these systems.

We found that Emission Factors (the total amount of enteric methane produced by an animal in one year) were up to 40% less than those produced by TIER I estimates—but that this was not uniform between or even within regions. . . .

[W]hile emissions on a per capita basis are low and much lower than for livestock in Western systems, the Emissions Intensities (i.e. emissions per unit of a product such as milk or meat) have been estimated to be approx. one order of magnitude higher. However, this is still subject to ongoing investigations.

Our studies also highlighted the heterogeneity present in ostensibly similar production systems. This implies that consideration needs to be given to identifying and quantifying the sources of variability in attempting to develop regional EFs in Africa. Our studies are the first of their kind for Sub-Saharan Africa relying on animal measurements . . . .

‘These findings are described in the articles entitled, A new approach for improving emission factors for enteric methane emissions of cattle in smallholder systems of East Africa—Results for Nyando, Western Kenya, recently published in the journal Agricultural Systems and Improved region-specific emission factors for enteric methane emissions from cattle in smallholder mixed crop: livestock systems of Nandi County, Kenya, recently accepted in the journal Animal Production Science.

‘This work was conducted by J. P. Goopy from the International Livestock Research Institute and the University of Melbourne, A. A. Onyango from the International Livestock Research Instituteand the University of Hohenheim, U. Dickhoefer from the University of Hohenheim, and K. Butterbach-Bahl from the International Livestock Research Institute and the Karlsruhe Institute of Technology. . . .’

Read the whole article by John Goopy: A new approach for estimating enteric methane emissions from cattle In smallholder livestock systems—first results, and implications for E. Africa, Science Trends, 25 May 2018.

See related news:
USA’s National Public Radio ‘All Things Considered’ program: How scientists in Kenya are trying to understand cow emissions, 29 May 2018.

ILRI Clippings blog: Green grass and greenhouse gas: Scientists are investigating the links between them, 3 Jun 2018.

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