Greenhouse gas emissions from ruminant supply chains – A global life cycle assessment

Greenhouse gas
emissions from
supply chains
A global life cycle assessment


Download full pdf version Download - 7.8Mb

Food and Agriculture Organization of the United Nations
Rome 2013


In decades to come, the global demand for livestock products will continue to increase driven by growing populations, incomes and urbanization. As a consequence the sector needs to produce more but in a context of increasing natural resource scarcity and challenges posed by climate change. In 2010, the ruminant sector contributed about 29 percent to global meat production (equivalent to 81 million tonnes) of which 79 percent is from the cattle sector and the remaining from buffalo and small ruminants. Global milk production in 2010 was 717 million tonnes with milk production from the cattle sector contributing the bulk, about 83 percent of global production. While ruminants play an important role in providing high quality protein essential for human diets, they are an important source of greenhouse gas (GHG) emissions. The demand for bovine meat, mutton and milk is forecasted to grow at a rate of 1.2 percent, 1.5 percent and 1.1 percent, respectively, during the period 2006-2050. To avoid significant increases in total GHG emissions from the sector, a reduction of the intensity of emissions is required. This report presents a life cycle analysis of the GHG emissions arising from ruminant supply chains around the year 2005. This first comprehensive and disaggregated global assessment of emissions enables the understanding of emission pathways and hotspots. This is a fundamental and initial step to identify mitigation strategies and inform public debate.

Table of Contents

Definitions of commonly used terms
Executive summary

  Download [115Kb]

1. Introduction

  Download [374Kb]
1.1 Background
1.2 Scope of this report
1.3 The Global Livestock Environmental Assessment Model
1.4 Outline of this report

2. Overview of the global monogastric sector


3. Methods

3.1 Choice of Life Cycle Assessment (LCA)
3.2 General principles of LCA
3.3 Use of LCA in this assessment
3.4 Overview of calculation method
3.5 Data sources and management
3.6 Allocation of emissions between products, by-products and services
3.7 Production system typology

4. Results

  Download [1,3Mb]
4.1 Cattle
4.2 Buffalo

4.3 Small Ruminants
4.4 Summary of results

  Download [787Kb]

5. Discussion

  Download [1.2Mb]
5.1 Methane emissions from enteric fermentation
5.2 Emissions from feed production
5.3 Emissions from manure management
5.4 Comparison with other studies
5.5 Analysis of uncertainty

6. Conclusion

6.1 Commercial systems (layers, broilers, industrial and intermediate pigs)
6.2 Backyard systems
6.3 Gaps in emission intensity within systems and regions



Overview of the Global Livestock Environmental Assessment Model (GLEAM)

  Download [362Kb]

Data and data sources


Changes in carbon stocks related to land use and land-use change

  Download [492Kb]

Postfarm emissions


Emissions related to energy use


Relative value of slaughter by-products and effect on allocation of emissions



  Download [1.1Mb]

1. Distribution of dairy cattle populations
2. Distribution of beef cattle populations
3. Distribution of buffalo populations

4. Distribution of goat populations
5. Distribution of sheep populations
6. Proportion of milk protein in total protein from cattle dairy herds

  Download [1,1Mb]
7. Average feed digestibility for dairy cattle
8. Average feed digestibility for beef cattle
9. Manure methane conversion factor for dairy cattle

  Download [1,1Mb]
10. Manure methane conversion factor for beef cattle
11. Proportion of feed N retained in product – dairy cattle herds
12. Proportion of feed N retained in product – beef cattle herds

  Download [1,2Mb]

Country list

  Download [117Kb]

The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned.

The views expressed in this information product are those of the author(s) and do not necessarily reflect the views or policies of FAO.

E-ISBN 978-92-5-107945-4 (PDF)

FAO encourages the use, reproduction and dissemination of material in this information product. Except where otherwise indicated, material may be copied, downloaded and printed for private study, research and teaching purposes, or for use in non-commercial products or services, provided that appropriate acknowledgement of FAO as the source and copyright holder is given and that FAO’s endorsement of users’ views, products or services is not implied in any way.

All requests for translation and adaptation rights, and for resale and other commercial use rights should be made via

FAO information products are available on the FAO website ( and can be purchased through [email protected].