International panel on climate change methodological approach

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Chapter 2 Direct methane and nitrous oxide emissions of South African dairy and beef cattle

Abstract

The objective of this study was to estimate direct methane and nitrous oxide emissions of South African dairy and beef cattle in total and per province using the Tier 2 methodology of the Intergovernmental Panel on Climate Change (IPCC), but adapted for tropical production systems. Dairy and beef cattle in 2010 contributed an estimated 964 Giga gram (Gg) or 72.6% of the total livestock methane emissions in South Africa. Beef cattle in extensive systems were the largest contributor (83.3%), followed by dairy cattle (13.5%), and feedlot cattle (3.2%). The enteric methane emission factors for dairy cattle of 76.4 kg CH4/head/year and 71.8 kg CH4/head/year for concentrate fed and pasture-based production systems, respectively, were higher than those reported by other developing countries, as well as the IPCC default value of 46 kg CH4/head/year for developing countries. The beef cattle methane emission factors were similar to those reported by other developing countries of 78.9 kg CH4/head/year and 62.4 kg CH4/head/year for commercial and emerging/communal cattle, respectively, but higher than the IPCC default value of 31 kg/head/year. Primarily because of cattle numbers, Eastern Cape recorded the highest dairy and beef cattle methane emissions, whereas Gauteng showed the highest feedlot methane emissions.
Keywords: methane, nitrous oxide, dairy cattle, beef cattle, feedlot# Corresponding author: dutoitcjl@tut.ac.za

Introduction

Recently South African livestock producers have come under increasing pressure over the environmental impact of production systems. The FAO (2006) reported that livestock contributed an
estimated 18% of global anthropogenic greenhouse gas (GHG) emissions. Livestock produce GHG’s in the form of methane (CH4) from enteric fermentation and nitrous oxide (N2O) and methane from manure management and manure deposited on pastures and veld (rangeland) by grazing animals. Agriculture, forestry and land use (corrected for carbon sink values) emitted an estimated 4.9% of South African GHG gases in 2004, which makes it the third largest GHG contributor in South Africa after the energy industry and industrial processes with 78.9% and 14.1%, respectively (DEAT, 2009). Livestock produced approximately 27% of the national methane gas total, mainly through enteric methane emissions from ruminants. Otter (2010) reported that livestock contributed 98% of the agricultural sector’s methane emissions. Methane is a potent GHG that remains in the atmosphere for approximately 9 to 15 years and is 25 times more effective in trapping heat in the atmosphere than CO2 over a 100-year period (FAO, 2006; IPCC, 2006). Nitrous oxide has an atmospheric lifetime of 150 years and a global warming potential of 296 times that of CO2 (IPCC, 2006). O’Mara (2011) stated that livestock GHG emissions relate closely with ruminant numbers, particularly cattle. In 2004, commercial beef cattle contributed 45% and emerging/communal cattle 33% of the total enteric fermentation of 1225 Giga gram (Gg) CH4 in South Africa with mature cows and bulls having the highest CH4 emission factors for enteric fermentation (Otter, 2010). South African livestock production is based on a unique combination of commercial (intensive and extensive) and emerging and communal (subsistence) production systems. The levels of productivity and efficiency in these production systems vary greatly in certain areas and it is important to distinguish between them when calculating GHG emissions. Methane production in livestock is influenced by several factors other than population numbers, including the size and productivity of animals, level of feed intake, diet composition, digestibility and quality of forage, forage species and cultivar, as well as variation among animals (Scholtz et al., 2012). Previous inventories (Blignaut et al., 2005; DEAT, 2009; Otter, 2010) were conducted on a national scale utilizing IPCC default values (Tier 1 approach) for some or all of their emission calculations.These emission factors do not distinguish effectively between classes of animals, production efficiencies, and production systems. They are often based on assumptions of animals utilizing highly digestible diets as well as temperate forages (Mills et al., 2001) which are not representative of South African production systems. It is important to generate accurate GHG baseline figures to develop South Africa’s capacity to understand and reduce GHG emissions from the livestock sector. The objective of this paper, therefore, is to re-calculate the direct methane and nitrous oxide emissions of dairy and beef cattle production in South Africa, taking into consideration the uniqueness of the South African scenario and using a refined Tier 2 approach. The Tier 2 methodology seeks to define animals, animal productivity, diet quality and management circumstances to support a more accurate estimate of feed intake for use in estimating methane production from enteric fermentation (IPCC, 2006). It was also considered important to do separate calculations for provinces as provinces differ in vegetation or biomes and production systems which may require different approaches to mitigation recommendations.Materials and Methods The methodology utilized is based on the Australian national greenhouse account’s National Inventory Report (ANIR, 2010), which contains Australian country-specific and IPCC default methodologies and emission factors. Emission factors specific to South African conditions and management systems were calculated where possible. A Tier 2 approach was adopted for all major cattle sectors, including dairy, beef and feedlot, in accordance with the IPCC Good Practice requirements (IPCC, 2006). The inventory was compiled on a provincial basis to reduce errors associated with averaging input data across areas with environmental, physical and managerial differences. The provincial totals were aggregated to produce national totals and the inventory was based on 2010 population data. Enteric fermentation The proportion of intake that is converted into methane is dependent on the characteristics of the animal, the quality and type of feed and the feed intake. South Africa is a country with diverse rainfall, temperature, and soil patterns (Smith, 2006), which gives rise to regional and seasonal variations in feed quality and quantity. Due to the heterogeneity of available feed types within South Africa it was considered important to use methodologies that could reflect such differences and was developed under similar conditions as in Australia (ANIR, 2009).

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Dairy cattle

Emissions from dairy cattle are based on commercial production systems. Cattle used for milk production in the emerging and subsistence farming sectors were incorporated under communal beef cattle emissions, since the milk yields are not high enough to meet the definition of a dairy cow. Data on provincial cow population figures and average daily milk production (10.5 kg/ day) were sourced from the commercial dairy industry and calculated from the number of dairy producers per province and the number of cows per producer (LACTO data, 2010). These figures were verified against the total annual milk production in 2010 (2.5 billion litres). The total number of dairy animals per province was then calculated according to the ideal herd composition of a 100 cow herd (Wasserman, 2005).

Contents
Acknowledgements
Preface
Executive summary
Thesis outputs
Table of Contents
List of Tables
List of figuresBookmark not defined.
List of abbreviations
General Introduction
Chapter 1
Review of literature
Introduction
Overview of global warming
International panel on climate change methodological approach
Greenhouse gas production in South Africa
Vulnerability of South Africa to climate variability.
Ruminant methane production
Factors influencing enteric methane production
Measuring methane emissions from livestock.
Individual animal techniques
Group techniques
In Vitro methods
Comparison of measuring techniques
Prediction equations and Models
Mitigation Options
Nutritional and management strategies
Manipulation of rumen fermentation
Improving animal efficiency
Conclusions and the need for future research
Chapter 2
Direct methane and nitrous oxide emissions of South African dairy and beef cattle
Chapter 3
Direct greenhouse gas emissions of the South African small stock sectors
Chapter 4
Direct greenhouse gas emissions of the game industry in South Africa
Chapter 5
Direct methane and nitrous oxide emissions of monogastric livestock in South Africa
Chapter 6
Nutrient composition and in vitro methane production of sub-tropical grass species in transitional rangeland of South Africa
Chapter 7
In vitro total and methane gas production of common South African improved sub-tropical and temperate grass species as influenced by nitrogen fertilization
Chapter 8
heep fed Eragrostis curvula hay substituted with Lespedeza cuneata
Chapter 9
General conclusion
Critical evaluation
Future research
References