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

Copyright resides with the authors in terms of the Creative Commons Attribution 2.5 South African Licence. See: http://creativecommons.org/licenses/by/2.5/za Condition of use: The user may copy, distribute, transmit and adapt the work, but must recognize the authors and the South African Journal of Animal Science. ________________________________________________________________________________ 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 of 78.9 kg CH4/head/year and 62.4 kg CH4/head/year for commercial and emerging/communal cattle, respectively, were similar to those reported by other developing countries, 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. ________________________________________________________________________________


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 (CH 4 ) from enteric fermentation, and nitrous oxide (N 2 O) 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 CO 2 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 CO 2 (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) CH 4 in South Africa with mature cows and bulls having the highest CH 4 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 Intergovernmental Panel on Climate Change (IPCC, 2006) good practice requirements.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).

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).
There are two major dairy production systems in South Africa, a total mixed ration (TMR)-based system and a pasture-based system.The liveweights of all classes of animals according to the herd structure was calculated according to data reported by Banga (2009) for Holstein cattle and Jersey cattle in TMRbased and pasture-based production systems.Banga (2009) reported that the national commercial dairy herd is composed of approximately 60% Holstein-type breeds and 40% Jersey-type breeds.This ratio was utilized to calculate the liveweight of animals used in the emission calculations.Liveweights of animals per age group were confirmed by using a prediction equation according to the Von Bertalanffy growth function given by Bakker & Koops (1978) as: Where: LW = liveweight M = mature weight (kg) W 0 = birth weight (kg) k = growth rate parameter t = age (months).
Variables used in the above equation were sourced from Banga (2009) and dairy breed societies in South Africa.Parameters used to predict the liveweight of the various classes of animals as reported by Banga (2009) are presented in Table 1.
Table 1 Parameters used to predict liveweight for each breed type and production system (Banga, 2009)  The animal weight, weight gain, diet characteristics and management data used in the algorithms to calculate emissions are presented in Appendix A. Daily methane production was calculated according to the Australian National Inventory Report (ANIR, 2009) based on dry matter intake.

Beef cattle
Population data for 2010 and the herd structure for commercial and communal beef cattle on a provincial basis were sourced from Statistics South Africa (Stats SA), the Department of Agriculture, Forestry and Fisheries (DAFF) and the Agricultural Research Council (ARC) of South Africa (StatsSA, 2010;DAFF, 2010;J. van der Westhuizen & H.E. Theron, 2012, Pers. Comm., SA Stud Book, P.O. Box 270, Bloemfontein, 9300, South Africa).
South African beef cattle production systems are mainly extensive and based on veld (i.e.rangeland or natural pastures).Tainton (1981) divided veld in South Africa into three broad types, namely sweetveld, sourveld and mixed veld.The percentage of each veld type in each province was estimated according to a map produced by Tainton (1999).The seasonal variation in veld quality and digestibly was sourced from the literature (Dugmore & Du Toit, 1988;De Waal, 1990;O'Reagain & Owen-Smith, 1996).
The commercial beef herd is composed of approximately 70% medium frame cattle (Bonsmara type), 15% large frame and 15% small frame (J.van der Westhuizen & H.E. Theron, 2012, Pers.Comm., SA Stud Book, P.O.Box 270, Bloemfontein, 9300, South Africa).Liveweights for each frame type were calculated from weight data published by Meissner et al. (1983) and verified with cattle breed societies.The average liveweight per beef cattle age group or class was estimated according to the ratio (above) of medium, large and small frame breed types (70:15:15).Communal cattle liveweights were calculated from the commercial cattle weights with a 20% reduction, since communal cattle are more Sanga and Zebu types, fed on lowerquality diets and with lower intakes.Liveweight, liveweight gain, feed characteristics and management data used in the algorithms are presented in Appendices B.1 to B.5.
Dry matter intake for each beef cattle class was calculated according to the equation presented by Minson & McDonald (1987) (Equation 1).Feed intake increases during lactation.It was assumed that the intake of all breeding cows increased by 30% during the season in which calving occurs and by 10% in the following season (SCA, 1990) as energy requirement for milk production declines during the second half of lactation.Additional intake for milk production (MA) was calculated as: MA = (LC x FA) + ((1 -LC) x 1)……………………………………………...………………….. Equation 6Where: LC = proportion of cows > 2 years lactating FA = feed adjustment (1.3 during the season of calving and 1.1 during the following season).

Feedlot cattle
The 2010 provincial data on cattle in feedlots were sourced from the South African Feedlot Association (SAFA, 2012).The feedlot enteric methane emission (Y), (MJ CH 4 /head/day) calculations are based on intake of specific diet components using an equation developed by Moe & Tyrrell (1979): 9Where: SR = intake of soluble residue (kg/day) H = intake of hemicellulose (kg/day) C = intake of cellulose (kg/day).
Feedlot calculations were based on the assumption that an animal will stay in the feedlot for approximately 110 days (three cycles per year).

Manure management
Methane production from manure management of dairy, beef, and feedlot cattle were calculated based on the approach of the IPCC (2006) using a combination of default IPCC and country-specific input values.The authors of the ANIR (2010) stated that high temperatures, high solar radiation and low humidity environments would dry manure rapidly and that methane production was likely to be negligible in manure of range-kept livestock.Gonzalez-Avalos & Ruiz-Suarez (2001) recorded a negligible amount of methane emitted from manure of cattle kept under conditions similar to those in South Africa and Australia.The Australian methodology calculated the manure emissions factor (MEF) of range-kept cattle in environments with an average temperature of 21 °C as 1.4 x 10 -5 kg CH 4 /kg DM manure, based on the results of Gonzalez-Avalos & Ruiz-Suarez (2001).

Dairy cattle
Methane emissions from manure originate from the organic fraction of the manure (volatile solids).Volatile solids (VS), (kg/head/day) for South African dairy cattle were calculated according to ANIR (2010) as: 11Where: I = dry matter intake calculated as described above DMD = dry matter digestibility expressed as a fraction (Appendices: A.1 and A.2) A = ash content of manure expressed as a fraction (assumed to be 8% of faecal DM).
The percentage of manure managed in different manure management systems in South Africa and the manure methane conversion factors (ANIR, 2010) for these systems are reported in Appendix A.3.Methane production from manure (M) (kg/head/day) was calculated as: M = VS x B o x MCF x p………………………………………………………………………… Equation 12Where: B o = emissions potential (0.24 m 3 CH 4 / kg VS) ( IPCC, 2006) MCF = integrated methane conversion factor -based on the proportion of the different manure management systems and the MCF for warm regions (Appendix A) p = density of methane (0.662 kg/m 3 ).
The integrated MCF for lactating dairy cattle in TMR-based production systems was calculated as 10.07% and 1% for all other classes of dairy cattle.In pasture-based production systems the integrated MCF for lactating cattle was calculated as 3.64% and 1% for all other classes of cattle.

Beef cattle
South African beef production systems are mainly extensive and manure is deposited directly onto pastures and not actively managed.Methane emissions from manure (M), (kg/head/day) of beef cattle were calculated according to the ANIR (2010) as: 13Where: I = intake as calculated under enteric emissions (Equation 1) DMD = dry matter digestibility across seasons (Appendix B.4) MEF = emissions factor (kg CH 4 /kg DM manure).The factor of 1.4 x 10 -5 based on the work of Gonzalez-Avalos & Ruiz-Suarez (2001) was used.

Feedlot cattle
The high stocking density of animals in feedlots results in a build-up of manure, which may lead to the production of methane, especially when the manure is wet.The method of manure management at a feedlot influences the amount of methane that is emitted from it.South African feedlots manage manure mainly by dry packing, which results in only a small fraction of potential methane emissions being generated (IPCC, 1997).The Australian national inventory (ANIR, 2010) reported default values for drylot methane conversion factors (MCF) of 1.5% based on the IPCC (1997).The volatile solid production for feedlot cattle was estimated based on data developed under the enteric methane emission calculations reported earlier.
The volatile solid production was calculated by equation 11 assuming a DMD of 80% for feedlot diets.The daily methane production from feedlot manure was then calculated using equation 12, assuming an emissions potential (B 0 ) of 0.17 m 3 CH 4 /kg VS (IPCC, 2006) and a MCF of 1.5% as stated above.

Beef cattle
Nitrous oxide emissions originating from beef cattle manure deposited on rangelands are not reported under livestock emissions (IPCC, 2006).The emission factor (kg N 2 O-N/kg N excreted) is reported to be 0 (IPCC, 2006).According to the IPCC ( 2006), nitrous oxide emissions from manure deposited on pasture or veld is reported under the managed agricultural soils sections in the national inventory report format and not under livestock emissions.Nitrous oxide emitted from soil through the metabolism of urine and faeces deposited directly on pastures or veld was calculated according to the ANIR (2009).
The amount of nitrogen retained in the body (NR), the nitrogen excreted in urine (U), and the total nitrous oxide emissions from feedlot cattle were calculated using equations 16 to 21 above.

Results and Discussion
The total methane emissions produced from South African livestock species in 2010 were estimated at 1328 Gg/year (Du Toit et al., 2012).Methane emissions from the South African cattle industries have been calculated as 964 Gg or 72.6% of the total livestock methane emissions during the same period.The contributions of dairy cattle, beef cattle on veld and feedlot cattle to the total cattle methane emissions were 13.5%, 83.3% and 3.2%, respectively.Otter (2010) reported the proportional contribution of dairy cattle as 14.3%, beef cattle on veld as 84.6% and feedlot cattle as 1.11% in South Africa.In comparison, livestock in Brazil produced a total of 9937 Gg during 1995 with beef cattle producing 80.9% and dairy cattle 13.6% of the total livestock methane emissions (Lima et al., 2002).Indian livestock produced a total of 9093 Gg of methane in 2006 with beef cattle producing only 35.9%, buffalo 7.08% and dairy cattle 19.9% of the total livestock methane emissions (Swammy & Bhattacharya, 2006).
The direct GHG emissions from all cattle (dairy, commercial beef, communal beef and feedlot cattle) in South Africa are presented in Table 2 on a provincial basis.The Eastern Cape province has the highest methane emissions profile originating from cattle followed by KwaZulu-Natal, Free State and the North West, reflecting to a large extent the population numbers.Otter (2010) reported the total enteric methane emission of all cattle classes as 1050 Gg and the methane emitted from manure as 97.1Gg based on 2004 population data using the IPCC Tier 2 approach.The enteric methane emission figures calculated for 2010 correspond well with the figures reported by Otter (2010) but there is large variation in the methane emissions originating from manure.These differences may be owing to the methodologies employed to calculate volatile solid excretion and the manure management systems allocated to different types of cattle.Western Cape, Free State, Gauteng and North West have the highest nitrous oxide emissions originating from cattle.This is owing to the number of dairy and feedlot cattle in these provinces as well as differences in management systems among them.The calculated methane emission factors (MEF) for South African dairy cattle are presented in Tables 3 and 4. Production systems based on concentrate feeds (TMR-based) have higher emission factors than pasture-based production systems except for the dry cow category.This is expected, owing to the higher digestibilities of concentrate-based diets as well as the higher intakes achieved by animals receiving concentrate diets.Lactating animals have the highest MEF, owing to increased energy requirements for production and differences in manure management systems compared with other dairy cattle classes.The calculated enteric and manure methane emission factors for South African dairy cattle are higher than dairy cattle emissions factors in other developing countries such as Brazil, with 62 kg/head/year and 3 kg/head/year, respectively, and India, with 35.5 kg/head/year and 3.65 kg/head/year, respectively, as reported by Lima et al. (2002) and Chhabra et al. (2012).The IPCC ( 2006) reported enteric and manure methane emission default factors for Africa of 46 kg/head/year and 1 kg/head/year, respectively.These figures are considerably lower than the national dairy herd average across all age groups of 76.4 kg/head/year and 71.8 kg/head/year for enteric emissions and 4.9 kg/head/year and 1.93 kg/head/year for manure emissions for TMR-and pasture-based production systems, respectively.These values are reported in Tables 3 and 4. South African calculated methane emission factors are more comparable with emission factors from developed countries for enteric and manure emissions such as the United Kingdom (109 and 28 kg/head/year), Australia (115 and 8.87 kg/head/year) and New Zealand (79.3 and 3.29 kg/head/year) as reported by ANIR (2010) and the New Zealand GHG Inventory (2010).
Table 5 reports total methane and nitrous oxide emissions for the dairy cattle on a provincial basis during 2010.The South African dairy industry consists predominantly of concentrate-based (TMR) production systems except for Eastern Cape and KwaZulu-Natal, which use mainly pasture-based production systems.Western Cape, Eastern Cape and KwaZulu-Natal are responsible for approximately 67.2% of the dairy industry's direct CH 4 emissions (Table 5).Approximately 81% of the total direct N 2 O emissions of 0.31 Gg are produced in Western Cape, Free State and North West (Table 5).Nitrous oxide emitted from soil through the metabolism of faecal matter deposited directly on pastures by dairy cattle was estimated at 0.88 Gg on a national scale.The South African beef industry is characterised by two distinct sectors, the commercial beef sector, including feedlot production systems, and emerging and communal (subsistence) production systems.These systems differ in breed type, feed availability, feed quality, level of production and production efficiency.The MEFs for commercial and communal beef production systems are reported in Tables 6 and 7, respectively.The emissions factors were calculated on a Tier 2 level (IPCC, 2006).Nitrous oxide emissions are not allocated to beef cattle, as the emission factor for manure deposited on veld (kg N 2 O-N/kg N excreted) is 0 and N 2 O emission from manure deposited on veld and pasture is reported under the managed agricultural soils section in the national inventory report format (IPCC, 2006).Penttilä et al. (2013) reported that dung beetles could potentially increase GHG emissions from livestock faeces voided on rangeland or veld, mainly due to increased N 2 O emissions.The possible effect of dung beetles is noted but not included in the present inventory due to insufficient data under South African conditions.Commercial cattle are heavier and have higher intakes of better quality diets than emerging sector and communal cattle.This results in higher MEF factors for commercial cattle.Although commercial cattle have higher MEF per head, they are more productive, and the methane emissions per kg product or per hectare should be lower than that of communal cattle.
The extensive beef cattle sector is the largest contributor to the cattle sector's GHG emissions, contributing 54.7% and 28.6% for commercial and emerging/communal cattle, respectively.The Eastern Cape has the highest beef cattle methane emissions in both commercial and emerging/communal production systems, followed by KwaZulu-Natal, Free State and the North West (Table 8).Although nitrous oxide emissions from faecal matter voided on veld or pastures are not reported under livestock emissions according to the IPCC (2006) good practice guidelines, these emissions are reported to provide a more complete scenario of emissions associated with extensive beef production systems in South Africa.Nitrogen in faecal matter is primarily organic and must first be mineralized before it becomes a source of N 2 O.The mineralization process occurs at significant rates in higher rainfall regions.However, the decay of faeces in drier areas is much slower, with faeces remaining largely intact for months to years (ANIR, 2009).The N 2 O emissions from faeces and urine voided on grazing was estimated at 1.3 Gg N 2 O/year for commercial cattle and 0.61 Gg N 2 O/year for communal cattle on a national scale using emissions factors of 0.005 and 0.004 Gg N 2 O-N/Gg N for faeces and urine, respectively, according to the ANIR (2009).
Feedlot cattle represent a small proportion of national cattle GHG emissions.This is owing to the relative small size of the industry and the duration the animals spend in a feedlot (approximately 110 days per cycle).The emission factors (kg/head/year) for feedlot cattle are presented in Table 9. Feedlot cattle have a relative high N 2 O emission factor in relation to their manure methane emissions factor compared to dairy cattle.
Gauteng represents approximately 42% of the total feedlot emissions, followed by Free State with 17.6% and North West with 17.4% (Table 9).The methane emissions from manure in the Western Cape and Eastern Cape are negligible and, owing to rounding of figures to two decimals, these figures are presented as 0.00 in Table 10.
Dry matter intake calculated for all cattle categories falls within the range reported by the IPCC (2006) of 1% -3% of body weight (BW).Dairy cattle intake figures ranged from 1.5% to 4.8% of BW, commercial cattle intake from 1.3% to 2.6% of BW, communal cattle intake from 1.6% to 2.7% of BW and feedlot cattle intake was estimated at 2.5% of BW.Dairy cattle heifers 2 -6 months and calves had a higher intake of 4.25% and 4.8% of BW, respectively.These intake figures correspond with intakes predicted for cattle of similar weight classes and production status in international sources (ANIR, 2010).The averaged calculated emissions factors for all cattle have been compared to the IPCC ( 2006) default values for Africa (Table 11).
The calculated dairy cattle emission factors are considerably higher than the IPCC (2006) default emissions factors for Africa.The IPCC based their emission factors for commercial dairy cattle on animals grazing with low production (average milk production of 475 kg/head/year).The milk production of South African commercial dairy cattle ranges from approximately 3000 to 5000 kg/head/year (LACTO data, 2010).The emissions factors calculated for lactating dairy cattle are more comparable with the IPCC default values for North America (128 kg/head/year), Western Europe (117 kg/head/year) and Oceania (90 kg/head/year) (IPCC, 2006).The IPCC does not report on feedlot emission factors for Africa, but the calculated emission factors are in line with feedlot values reported for North America (Table 11).The calculated enteric emission factors of veld/extensive beef cattle range from 51.6 kg/head/year to 113 for commercial beef cattle and 40.9 -83.8 kg/head/year for emerging/communal beef cattle with a herd average of 79 kg/head/year and 62.4 kg/head/year, respectively, which is higher than IPCC default values for Africa.These values correspond well with those for range kept beef cattle in Australia of 72 kg/head/year as reported by the ANIR (2010).The differences in the calculated emission factors and the IPCC default values are mainly because of variations in liveweight and animal productivity used in the calculations.The IPCC calculated emission factors for Africa based on smaller, less productive cattle fed on low-quality diets, which are not representative of South African production systems.The methane emission factors calculated for South African cattle are compared to other developing countries in Table 12.South African cattle emitted more methane annually than Brazilian and Indian cattle (Table 12).The dairy cattle emissions reported in Table 12 are for lactating animals only.The estimated enteric emission factors for South African cattle are higher across all cattle types compared with other developing countries, Brazil and India, which have smaller animals fed on lower-quality diets.McGinn et al. (2007) and Loh et al. (2008) reported the enteric emission of feedlot cattle of Canada and Australia as 78.1 kg/head/year and 60.6 kg/head/year, respectively.Hegarty et al. (2007) reported the feedlot enteric methane emissions under Australian conditions as ranging from 51.8 kg/head/year to 69.4 kg/head/year.The calculated emission factor from South African feedlot cattle of 58.9 kg/head/year is in line with these values.Canadian feedlot cattle are mainly Bos taurus-type cattle.South African feedlots contain a large percentage of Bos indicus-type cattle, which are well adapted to local conditions and should have lower MEF than Bos taurus cattle owing to lower intakes.Kurihara et al. (1999) measured emissions from Bos indicus cattle under feedlot conditions and fed high grain diets as 48.9 kg/head/year.

Conclusion
Cattle are a major source of methane emissions from the livestock sector in South Africa, contributing approximately 72.6% of the total livestock GHG emissions.Commercial beef cattle on veld are the major methane emitters, followed by emerging/communal beef cattle, dairy cattle and feedlot cattle.Dairy cattle are the major contributors to direct nitrous oxide emission from cattle.The methane emission factors calculated for commercial dairy and beef cattle production systems are more comparable to emission factors from developed countries (North America, Western Europe and Oceania) and the emerging/communal production systems to those of developing countries (Brazil and India).The IPCC default values for Africa underestimate emission factors across all cattle categories.The large variation in emission factors among countries and IPCC default values is primarily owing to differences in animal production systems, feed types and nutrient use efficiency by animals.This emphasizes the need to develop country-specific emission factors for enteric and manure emissions, as well as nitrous oxide emissions factors from manure through quantitative research.

Table 2
Provincial and total cattle methane and nitrous oxide emissions, 2010 *N 2 O emissions originating from fertilized pastures and faecal matter voided at pasture or veld is not included.Gg: Giga gram.

Table 3
Direct methane and nitrous oxide emission factors for TMR-based dairy cattle, 2010 MEF: methane emissions factor.* kg/head/year.

Table 4
Direct methane and nitrous oxide emission factors for pasture-based dairy cattle, 2010

Table 5
Provincial and total methane (Gg) and nitrous oxide (Gg) emissions of dairy cattle based on 2010 data ¤ LACTO data (2010); Gg: Giga gram.* N 2 O emissions originating from fertilized pastures and faecal matter voided at pasture or veld is not included.

Table 6
Methane emissions factors for commercial beef cattle MEF: methane emissions factor; kg/h/year: kg/head/year.

Table 7
Methane emissions factors for communal beef cattle MEF: methane emissions factor; kg/h/year: kg/head/year.

Table 8
Provincial and total methane emissions of extensive beef cattle based on 2010 data

Table 9
Direct methane and nitrous oxide emission factors for South African feedlot cattle

MEF enteric (kg/h/year) MEF manure (kg/h/year) N 2 O* (kg/h/year)
N 2 O emissions originating from fertilized pastures and faecal matter voided at pasture or veld is not included. *

Table 10
Provincial and total GHG emissions of South African feedlot cattle based on 2010 data # Values too small to include; Gg: Giga gram.*Valuesexclude N 2 O emissions originating from fertilised pastures and faecal matter voided at pasture or veld.

Table 11
Average calculated enteric methane emissions factors compared to IPCC default values for Africa (kg/head/year)

Table 12
Enteric methane emission factors for South African, Brazilian and Indian cattle LW: liveweight; DMD: dry matter digestibility; EF: Emissions factor.*Value excludes the positive effect of supplementation on diet digestibility in commercial production systems.1 Lima et al., 2002; 2 Swammy & Bhattacharya, 2006.