Evaluation of methane measuring techniques

Evaluation of different techniques to quantify methane emissions from South African livestock

Industry Sector: Cattle and Small Stock

Research focus area: Sustainable natural resource utilization

Research Institute: University of Pretoria

Researcher: Dr JL Linde du Toit

Title Initials Surname Highest Qualification
Prof WA van Niekerk PhD
Mr J van Wyngaard MSc
Mrs Z Goemans BSc(Agric)

Year of completion : 2018

Aims of the project

  • To measure methane emissions from livestock using the SF6 technique
  • To measure methane emission from livestock using the handheld laser methane detector (LMD) technique
  • To compare the results of the SF6 and the LMD techniques

Executive Summary

The need to verify greenhouse gas inventories demands the development of high throughput, economical yet accurate short-term measurement techniques, such as the laser methane detector (LMD). The aim of this project was to compare methane (CH4) emission rates as measured by the LMD to the sulphur hexafluoride tracer gas (SF6) technique from lactating dairy cows grazing pasture and to evaluate the practicality of the LMD measurement protocol under grazing conditions in the temperate coastal region of South Africa. Methane production was determined from six lactating Jersey cows on pasture using both techniques. The data generated by the LMD had a superior daily repeatability compared to the SF6 technique in the present study. A higher between-cow coefficient of variation (CV) (0.6 vs. 0.4) from the LMD compared to the SF6 technique was observed and this was ascribed to the sensitivity of the LMD to ambient conditions, animal movement while grazing and time of measurement. Methane production as measured by the SF6 technique (348 g/d) was higher (P<0.05) compared with the LMD technique (82.6 g/d).

Results from this study indicated that the LMD yielded approximately a 70% lower average daily CH4 production when compared to the SF6 techniques under the experimental conditions and daily CH4prediction models using the same animals and dry matter intakes. The lack of a third measuring technique and a standardized LMD methodology makes an accurate comparison between techniques and published data difficult. Both the SF6 and the LMD methods are viable methods to evaluate differences between mitigation options, for ranking of animals for selection purposes and to identify differences between dietary treatments. More research is needed before new techniques such as the LMD can be employed to determine absolute CH4 daily emissions which can be up scaled for inventory purposes.

Popular Article

Measuring methane from livestock

Recently, methane has been reported as the most abundant organic trace gas in the atmosphere. The radiative forcing of methane (CH4) is significantly higher than carbon dioxide (CO2) and it is estimated that CH4 has a global warming potential of 28 compared to CO2 with an atmospheric half-life of 12.4 years1. Enteric production of CH4 from ruminant livestock production systems is one of the major sources of agricultural greenhouse gas emissions globally. The relatively short atmospheric half-life of CH4 makes it the main target in livestock greenhouse gas mitigation protocols. Methane is also an important indicator of livestock productivity as it is associated with the conversion of feed into animal product i.e meat, milk or fibre.

Methane is produced in the rumen by methanogenic bacteria as a by-product of the fermentation process. Ruminal fermentation by rumen microbes result in the formation hydrogen (H2). Accumulation of excessive amounts of H2 in the rumen negatively affects the fermentation rate and growth of some microbial consortia which will reduce feed intake and production of animals. Methanogens therefore reduce carbon dioxide (CO2) to methane (CH4) and water (H20) thereby capturing available hydrogen and sustaining a favorable fermentation environment in the rumen2. Methane is exhaled or belched by the animal and accounts for the majority of emissions from ruminants. Methane also is produced in the large intestines of ruminants and is expelled in much smaller volumes compared to ruminal methane.

There are a variety of factors that affect CH4 production in ruminant animals, such as: the physical and chemical characteristics of the feed, the feeding level and schedule, the use of feed additives to promote production efficiency, and the activity and health of the animal1. Reductions in greenhouse gas emissions from livestock can be achieved through a range of CH4 mitigation strategies and more efficient livestock production systems through improved genetics and management.

Regardless of the mitigation strategy imposed, any reduction in enteric methane production must be quantified and for this to be achieved, accurate baseline emissions data are essential1. There are currently many techniques available to researchers to quantify CHemissions from livestock each with specific applications and challenges. These techniques vary from tracer and capsules for individual ruminants to whole farm systems. The development of baseline emission data can also be achieved through modeling, employing specific livestock and environmental activity data to estimate emissions. One of the main challenges of the majority of the measurement techniques is the lack of “real time” emissions from grazing ruminants under natural conditions. There is a need to develop measuring techniques and methods which can be standardized, is relatively low-cost and which can deliver reliable, feasible and repeatable assessments of emissions from grazing livestock.

The Sulphur hexafluoride (SF6) technique and spot sampling lasers are two of the techniques which shows promise to measure CHemission from grazing livestock. Researchers recently compared these two techniques in a pasture dairy production system in the Western Cape province of South Africa. It was found that the spot sampling with the laser could be useful for purposes such as selective animal breeding and comparing between different mitigation strategies, where the requirement is for relative emission data but not necessarily daily methane production. This trial highlighted the need to develop specific operational standards when employing methane quantification techniques under natural conditions in order to minimize variation and environmental interference when recording measurements.

Strategies to reduce greenhouse gas emissions and to increase farm productivity are likely to remain vague, random and possibly inefficient without the development of standardized, accurate and reliable CH4 measurement techniques1.

References

  1. Hill, J., McSweeney, C., Wight, A.G., Bishop-Hurley, G. and Kalantar-zadeh, K., 2016. Measuring methane production from ruminants. Trends in Biotechnology, Vol. 36 (1).
  2. Goopy, J., Chang, C. and Tomkins, N., 2016. A Comparison of Methodologies for Measuring Methane Emissions from Ruminants. In: Methods for Measuring Greenhouse Gas Balances and Evaluating Mitigation Options in Smallholder Agriculture. Editors: Todd S. Rosenstock, Mariana C. Rufi no Klaus Butterbach-Bahl, and Eva Wollenberg Meryl Richards. Springer International Publishing AG Switzerland.
Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Linde du Toit on linde.dutoit@up.ac.za

Methane and nitrous oxide from beef cattle manure

Direct manure methane and nitrous oxide emissions from a commercial beef feedlot in South Africa.

Industry Sector: Cattle and Small Stock

Research focus area: Sustainable natural resource utilization

Research Institute: University of Pretoria

Researcher: Dr JL Linde du Toit

Title Initials Surname Highest Qualification
Prof WA van Niekerk PhD
Miss K Lynch BSc(Agric)
Dr L Stevens PhD

Year of completion : 2017

Aims of the project

  • To identify the on-farm manure management system employed in a typical commercial beef feedlot in South Africa
  • To determine the methane emissions from manure in a commercial beef feedlot
  • To determine the nitrous oxide emissions from manure in a commercial beef feedlot

Executive Summary

Methane and nitrous oxide emission from pen surfaces in a commercial beef feedlot in South Africa

Global warming has become a worldwide concern in recent years.  The release of Greenhouse gasses (GHGs) have brought about rapidly changing climate conditions the world over, GHGs produced by various industry sectors are being investigated, researched and laws put in place to limit the production of GHGs wherever possible.  This includes the agricultural sector where extensive animal husbandry has increased the global carbon footprint and environmental pollution.

The International Panel of Climate Control (2006) has three Tiers that estimates methane (CH4) values, one of the main GHGs, from the use of default values to the use of more complicated models and experimental data to improve the accuracy of reporting.  This study investigated the contribution of manure GHGs emissions to livestock emissions focussing on intensive beef feedlot manure emissions. At present in South Africa, these values are only roughly estimated and are only available on an IPCC Tier 2 level.  Gaseous emissions from livestock waste, specifically beef cattle waste, are affected by a variety of external factors (atmospheric temperature, humidity, soil conditions, ration consumption and manure management practices) as well as internal factors, (ration digestibility, nutrient absorption and gut health).

The objective of the study was to achieve an understanding of the gaseous emissions, specifically methane (CH4) and nitrous oxide (N2O), from beef cattle feedlot pen surfaces from a commercial beef feedlot in South Africa as influenced by diet and season, using the closed chamber method of gas collection over the three prominent seasons experienced in Mpumalanga, South Africa.  The sampling of these various factors would lead to more accurate reporting, conforming to Tier 3 methodology results.

Random pen surface and emissions samples were taken from three pens per each feedlot ration fed. The results indicated significant differences in soil/manure characteristics, but little effect on ultimate CH4 and N2O emissions from the pen surface were found across treatments. Similar results were observed for the rangeland manure analysed and manure emissions from manure management practices at the feedlot.  Ambient temperature had a tendency (p<0.10) to affect CH4 and N2O emissions with higher temperatures resulting in higher emissions but. Overall soil and manure characteristics were affected by diet treatments and seasonal variation.  It must be noted that the lack of significant differences in gas emissions in the present study could have been due to sampling error. The gas emissions observed did show a trend between treatment levels and manure management practices within the feedlot, with the effluent dams and manure piles recording the highest CH4 emissions over each of the measured seasons.  The CH4 emissions varied between seasons within the feedlot, rangeland and manure management practices, but a level of significance was never observed even though manure characteristics observed significant differences.  The N2O emissions observed no set trend between areas measured on the feedlot.  The varying values, and negative values obtained may indicate sample error, or a general uptake of N by soil or microorganisms (Chantigny et al., 2007; Li et al., 2011).

In conclusion, it was found that manure characteristics are affected by season and diet characteristics which tended to have an effect on the rate of CH4 and N2O emissions from the manure, although not significantly.

Popular Article

Feedlot greenhouse gas study analyses emissions from pen surfaces and manure management

By CJL du Toit

Researchers from the University of Pretoria spend time at a commercial beef feedlot in Mpumalanga, South Africa to gain a better understanding of the greenhouse gas emissions originating from feedlots pen surfaces and manure.

Why are GHG emissions important to agriculture?

In agriculture and livestock production systems the three main greenhouse gases (GHG) include methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2).  Greenhouse gases impact the environment through their ability to trap heat which depends on their capacity to absorb and re-emit infrared radiation and the atmospheric life time of the different gasses.  Increasing atmospheric concentrations of GHG caused by fossil fuel combustion, industrial activities, land use change and agricultural activities contributes to changes in global temperatures and rainfall patterns which could impact directly on agricultural and livestock production.

Accurate estimation of GHG from anthropogenic sources is an increasing concern given the current and potential future reporting requirements for GHG emissions.  Research measuring GHG emission fluxes from feedlot surfaces and manure management has been very limited and this was the first research project on the topic under South African conditions.

Livestock manure and GHG emissions

Livestock manure is a source of nutrients and can be used for various purposes including soil amendments to improve fertility and productivity and the generation of green energy.  The main GHG emitted by manure are CH4 and N2O. Methane is produced during anaerobic decomposition of organic matter and N2O is emitted during nitrification and de-nitrification processes. Feedlot manure GHG emissions is influenced by a variety of factors including manure management (pile, anaerobic lagoon, rangeland), manure application (fertilization of rangeland, composting, bio-fermentation), temperature, aeration, moisture and the sources of nutrients in the manure which is in part caused feed inefficiencies. Emission is also influenced by animal factors in the feedlot such as stocking density which will influence the amount of manure deposited, feed intake and digestibility, animal type and age.

What did the researchers do?

Following an extensive review of current literature on GHG emission flux quantification from pasture, cropping and livestock enterprises it was decided to adopt closed static chambers as the measurement methodology. The aim of the study was to determine the effect of feedlot ration and season on the GHG emissions from manure at different sites within in a commercial feedlot operation. Chamber bases were randomly installed at each manure management site (rangeland, pen surface, manure piles and water catchment lagoons) during each season. The seasons were classified as wet and hot (WH), dry and cold (DC) and dry and hot (DH).

Gas samples were drawn from the chambers during mid-day at four time intervals within a 40 min measuring period and analysed using a gas chromatograph to determine average CH4 and N2O fluxes.

What did the researchers learn?

The method employed resulted in large variation within results sets mainly due to difficulty in sealing the chambers bases especially in the pen surfaces which were extremely compacted. The random placement of chambers also caused variation in results as some chambers had a higher manure density and factors such as soil and manure moisture varied between different locations within each pen.  The results yielded an average pen surface manure CH4 emission factor of 449 g/head/year which was 50% lower compared to feedlot manure emission factors previously calculated of 870 g/head/year using IPCC (2006) based models.  The N2O emissions measured from pen surfaces (10.95 g/head/year) were much lower than previously calculated or reported emission factors in literature varying from 54.8 to 2555 g N2O/ head/year.  Within the whole manure management system on the feedlot CH4 emissions from the water catchment dams were the highest followed by manure piles, feedlot pen surfaces and manure deposited on rangeland.  Although no statistical differences were found between the different seasons the wet and hot season produced the highest overall CH4 emissions and the dry and cold season produced the highest N2O emission across all manure management sites.

Managing GHG emissions from manure

The mitigation of GHG emissions from manure management in livestock operations is the topic of many research projects globally. Identified mitigation strategies are already being used by producers but new techniques and fine-tuning of existing options will lead to new and improved alternatives which can be tailored to country or regions specific production systems. The mitigation of GHG emissions from livestock production systems can be complicated as a strategy that reduces one emission may increase the other. Manure emissions can be reduced through two main actions namely input (providing of organic matter e.g. feeds) and manure management.  Overfeeding of nutrients such as nitrogen (N) will result in an increase in the amount of N excreted in manure which will lead to increased N2O emissions. To reduce GHG emission from manure producers will have to use feeding regimes that will maximise feed efficiency and reduce nutrient wastage. The management of on-farm manure can also be tailored to reduce GHG emissions and the effect of production systems on the environment.  The time of manure application to soil and rangeland is important to reduce emissions. Producers should avoid spreading manure when soil is are wet as this will increase CH4 emissions and attempt to reduce the storage time of manure on the farm. The use of technologies such as covered lagoons, digesters, aeration of manure and composting has all been employed to reduce CH4 emissions from manure.

On-going research

There is a need to develop standardised research methodology protocols, for both on-farm and laboratory experiments, which will make it possible to compare mitigation strategies and research results between different studies. Researchers are also attempting to understand the interplay of CH4 and N2O as it seems that the processes that produce these GHG are related.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Linde du Toit on linde.dutoit@up.ac.za

Nutrient content of lamb and mutton offal

The nutritional composition of South African lamb and mutton offal

Industry Sector: Cattle and Small Stock

Research focus area: Red Meat Safety, Nutritional Value, Consumerism and Consumer Behaviour

Research Institute: University of Pretoria

Researcher: Dr B Pretorius

Title Initials Surname Highest Qualificaion
Prof HC Schönfeldt PhD
Ms C Muller MSc
Dr N Hall PhD
Ms M Bester MSc
Ms D Human Matric

Year of completion : 2018

Aims of the project

  • To determine the nutritional composition of South African lamb and mutton offal products (raw and cooked)
  • To determine yield, retention and physical composition of the different cooked offal products to ultimately determine the edible portion of each product
  • To incorporate the nutritional composition data and physical composition data into the national food composition tables as well as the food quantities manual of the Medical Research Council

Executive Summary

Offal, also called variety meats, or organ meats or the ”fifth quarter”, have been overlooked in the past in dietary guidelines and recommendations, irrespective of their potential contribution to food and nutrition security. This study focussed on understanding the physical and nutrient composition, as well as the potential nutritional contribution of lamb and mutton offal, when used in the correct amounts, to South African diets.

Significant amounts of protein, iron and zinc (three nutrients of concern in South Africa) can be found in selected organ meats which compared favourably with beef and lamb muscle meat cuts. The most significant findings of the study were the high levels of protein (>10g/100g) found in all cooked lamb and sheep offal cuts ranging from 14.26g/g (cooked lamb intestines) to 32.6g/100g (cooked sheep kidneys). High levels of total iron were found in cooked sheep lungs (TFe=10.73mg/100g); cooked sheep spleen (TFe=11.71mg/100g); cooked sheep liver (TFe=7.95mg/100g) cooked lamb lungs (TFe=8.368mg/100g) and lamb spleen (TFe=22.83mg/100g).

Instead of simply focussing on total protein, attention has shifted to the greater importance of protein quality than actual quantity, emphasising the presence of individual amino acids in a food. Protein quality answers two important questions namely, how much protein as well as what kind of protein should be consumed. Dietary proteins are classified as either being complete or incomplete. Foods containing all essential amino acids (indispensable amino acids) are referred to as a complete protein. The sum of the essential amino acids for lamb and mutton offal varies between 4.2 g/100g and 8.1 g/100g for mutton tongue and liver respectively. The study found that South African lamb and mutton offal adheres to the requirements as set out by the Department of Health to be labelled and proclaimed as a complete, quality protein.

Offal products contribute consistently to the diet not only in terms of essential fatty acids such as linoleic acid (C18:2n-6) and arachidonic acid (C20:4 n-6), but also eicosanoic (arachidic) acid (C20) and docosanoic acid (C22) polyunsaturated fatty acids. Ruminant meats and oily fish are the only significant sources of preformed and C22 PUFA in the diet (Enser, et al., 1998; Wyness, et al., 2011). Although human beings have the metabolic capacity to synthesize C20 and C22 fatty acids from the n-6 or n-3 precursors of linoleic and α-linolenic acid respectively, an increase in the consumption of C20 and C22 n-3 polyunsaturated fatty acids could overcome the perceived imbalance in the ratio of n-6:n-3 polyunsaturated fatty acids in modern diets.

Based on the results of this study South African lamb and mutton offal cuts can be considered a good source of protein and also a nutrient dense food source. Due to the current state of nutrition in South Africa such foods are important commodities and the promotion thereof should be prioritised.

Popular Article

Nutrient density lamb and mutton offal

1Pretorius, B., 1,2Schönfeldt, H.C. and 1Bester, M.

1Department of Animal and Wildlife Sciences, Institute of Food, Nutrition and Well-being. University of Pretoria. South Africa

2Professor and Director: ARUA Centre of Excellence: Food Security

Despite economic growth, undernutrition and food insecurity remain today at unacceptably high levels, while at the same time, diet-related non-communicable diseases (cardiovascular diseases, diabetes and hypertension) have exponentially increased to become the leading cause of mortality worldwide. The situation is set to worsen dramatically in the near future as powerful drivers of change such as population growth, climate change and urbanization converge on food systems. Consumption recommendations for high quality nutrient dense foods such as animal source foods (ASFs) are of utmost importance and should be adhered to, to keep up with the specific physiological demands of each life stage. However it was found that the feasibility for nutritionally vulnerable individuals in South Africa to adhere to these recommendations seems unlikely. The dire economic climate which South Africans, particularly those of low socio economic status, currently have to face, is probably the main reason for the problem that nutritionally vulnerable individuals cannot meet the recommendations of the Food-based Dietary Guidelines for South Africans.

Offal has been overlooked in the past in dietary guidelines and recommendations, irrespective of their potential contribution to food and nutrition security in South Africa. Limited information is available on the composition of South African lamb and mutton organ meats as cooked and consumed at home. This study focussed on understanding the physical and nutrient composition, as well as the potential nutritional contribution of lamb and mutton offal, when used in the correct amounts, to South African diets.

Table 1: Moisture, fat and protein content of 100g edible portion cooked lamb & mutton offal

Lamb Mutton
n=3 Moisture Protein Fat Moisture Protein Fat
  g/100g g/100g g/100g g/100g g/100g g/100g
Intestines 55.2cd 14.3d 31.2a 48.2d 15.3d 37.9a
Lungs 74.1a 21.1bc 6.53b 71.1a 23.2bc 3.97d
Hearts 65.1b 19.3cd 13.5b 57.6bc 20.4cd 20.2c
Livers 61.2bc 23.6bc 8.39b 64.5ab 23.1bc 6.27d
Stomachs 49.6d 24.8ab 29.9a 53.1cd 17.8d 27.3bc
Kidneys 65.8b 24.4abc 12.1b 57.2bcd 32.7a 7.77e
Spleen 67.1ab 29.5a 6.62b 66.2ab 27.8ab 5.23e
Tongues 63.7b 19.2cd 16.8b 52.6cd 15.8d 33.2ab
P-value <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

Note: Means with different superscripts in a column differ significantly

Table 2: Mineral content of 100g edible portion cooked lamb offal

Ca P Mg Cu Fe Zn K Na
n=3 mg/100g mg/100g mg/100g mg/100g mg/100g mg/100g mg/100g mg/100g
Intestines 18.6b 124e 21.9a 0.28b 1.40c 2.60c 75.1d 38.4f
Lungs 8.90b 271c 22.2a 0.46b 8.37b 2.59c 298b 160b
Hearts 5.12b 195d 29.0a 0.49b 3.84bc 2.49c 261b 101cd
Livers 5.03b 423a 28.3a 17.9a 6.07bc 4.17a 315b 70.8e
Stomachs 52.7a 170de 25.3a 0.40b 4.85bc 3.90a 155c 79.5de
Kidneys 9.38b 330b 30.6a 0.53b 4.44bc 3.67a 310b 234a
Spleen 7.57b 406a 30.8a 0.29b 22.8a 3.60ab 409a 112c
Tongues 17.7b 184d 24.0a 0.31b 1.50bc 2.83ab 276b 102cd
P-value <0.001 <0.001 0.132 <0.001 <0.001 <0.001 <0.001 <0.001

Note: Means with different superscripts in a column differ significantly

Table 3: Mineral content of 100g edible portion cooked mutton offal

Ca P Mg Cu Fe Zn K Na
n=3 mg/100g mg/100g mg/100g mg/100g mg/100g mg/100g mg/100g mg/100g
Intestines 16.6b 112c 16.9cd 0.15b 1.69e 2.55b 50.2d 29.5e
Lungs 11.0bc 250b 19.4bcd 0.41b 10.7a 2.62b 285bc 190b
Hearts 6.00c 223b 24.8ab 0.65b 4.54c 2.74b 275bc 97.5cd
Livers 5.60c 399a 26.2ab 31.87a 7.96b 4.38a 326bc 78.7cde
Stomachs 24.6a 112c 15.9d 0.25b 2.70de 3.37ab 104d 58.7de
Kidneys 15.6b 400a 30.7a 0.56b 4.34cd 4.49a 279bc 270a
Spleen 6.00c 414a 31.4a 0.15b 11.7a 3.61ab 472a 112cd
Tongues 8.70c 142c 23.3bc 0.20b 1.81e 2.91b 235c 122c
P-value <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

Note: Means with different superscripts in a column differ significantly

Table 4: Contribution to NRV’s and nutrient content claims per 90g cooked offal meat
INRV according to the Foodstuffs, Cosmetics and Disinfectants act (DOH, 2014)

Protein Calcium Phosphorus Magnesium Iron Manganese Zinc Potassium Sodium
NRVI 56g 1300mg 1250mg 365mg 13mg 2.3mg 10mg 4700mg 2000mg
Mutton % of NRV per 90g servingII III
Intestines 25IV 11 8 0 12 0 23 IV 1 1
Lungs 37v 7 18 IV 0 74 VI 0 24 IV 5 9
Hearts 33 0 16 IV 0 31v 0 25 IV 5 4
Livers 37v 0 29 IV 0 55v 0 39v 6 4
Stomachs 29 IV 2 8 0 19 IV 0 30v 2 3
Kidneys 52v 1 29 IV 0 30v 0 40v 5 12
Spleen 45v 0 30v 0 81 VI 0 32v 9 5
Tongues 25IV 1 10 0 13 0 26 IV 4 5
Lamb % of NRV per 90g servingII III
Intestines 23IV 1 9 0 10 0 23 IV 1 2
Lungs 34v 1 19 IV 0 58v 0 23 IV 6 7
Hearts 31v 0 14 0 27 IV 2 22 IV 5 5
Livers 38v 0 30v 0 42v 10 38v 6 3
Stomachs 40v 4 12 0 34v 8 35v 3 4
Kidneys 39v 1 24 IV 0 31v 2 33v 6 11
Spleen 47v 1 29 IV 0 158VI 0 32v 8 5
Tongues 31v 1 13 0 10 0 25 IV 5 5

 II 90g is the prescribed portion size for lean meat according to the Food-based dietary guidelines for South Africans (Schönfeldt, Pretorius, & Hall, 2013)

III Values do not take bioavailability into account

IV ” Source of” as per the Foodstuffs, Cosmetics and Disinfectants act (DOH,2014)

v “” High in” as per the Foodstuffs, Cosmetics and Disinfectants act (DOH,2014)

VI ” Excellent source” as per the Foodstuffs, Cosmetics and Disinfectants act (DOH,2014)

South African lamb and mutton offal can be considered a good source of protein and a nutrient dense food. In the case of protein, zinc and iron, three nutrients of concern in South Africa, all lamb and mutton organ meats were at least a source of two out of these three nutrients with lamb and mutton spleens and lamb and mutton lungs being excellent sources of protein. In view of the current disturbing state of nutrition in South Africa, as well as efforts to reduce food waste, lamb and mutton organ meats were found to be important food commodities and it was suggested that the promotion of offal should be prioritised.

Quantitative food data goes hand in hand with the nutrient composition tables used in a given country, because it provides supporting information on the food items included in the nutrient composition tables. Good quality nutrient composition and quantitative food data play an integral role in reporting the nutrient intake of a population, as well as interpreting results of certain epidemiological research. A new set of quantitative data on the nutrient and physical composition (meat, bone and fat fractions) and yield of different offal cuts were generated to assist researchers in collecting more precise, product specific data to measure nutrient in South African food consumption studies.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Beulah Pretorius on beulah.pretorius@up.ac.za

Greenhouse gas emissions from livestock

Characterization of breed-specific additive and heterosis effects on beef sensory and leather quality traits

Industry Sector: Cattle and Small Stock

Research focus area: Sustainable natural resource utilization; Livestock production with global competitiveness

Research Institute: Tshwane University of Technology, University of Pretoria

Researcher: Mr CJL du Toit

Research Team:

Title Initials Surname Highest Qualification
Prof WA van Niekerk PhD
Dr HH Meissner PhD
Dr L Otter PhD

Final report approved: 2014

Aims of the project

  • To calculate on a regional basis the enteric methane emissions from all relevant livestock sectors
  • To calculate on a regional basis the methane emissions from livestock manure
  • To calculate on a regional basis the nitrous oxide emissions from livestock manure

Executive Summary

There are increasing concerns about the impact of agriculture and livestock production on the environment. The objective of the study was to estimate methane and nitrous oxide emissions of South African livestock industries during 2010 on a provincial and national basis. The study focused on direct methane (CH4) and nitrous oxide (N2O) emissions originating from enteric fermentation and livestock manure management systems. Both methane and nitrous oxide are potent greenhouse gasses with 25 and 310 times the global warming potential of carbon dioxide. The Intergovernmental Panel on Climate Change (IPCC) Tier 2 methodology adapted for tropical production systems was used to calculate emissions.

The Tier 2 methodology defines animals, animal productivity, diet quality and management circumstances to support a more accurate estimate of feed intake for use in estimating methane production. Livestock, including privately owned game, emitted and estimated 1330.6 Gg of CH4 and 3.28 Gg of N20 during 2010. In South Africa, the principle species comprise of cattle, game and sheep producing collectively an estimated 95% of the total livestock emissions. Commercial beef cattle were the largest contributors of methane followed by emerging and subsistence cattle, sheep, game, dairy cattle, goats and feedlot cattle with 527 Gg, 276 Gg, 167 Gg, 131 Gg, 130.5 Gg, 40.7 Gg and 30 Gg of methane respectively. The poultry industry emitted the highest amount of N2O producing an estimated 2.61 Gg followed by dairy cattle, horses and pigs with 0.54 Gg, 0.09 Gg and 0.04 Gg of N2O respectively. The Eastern Cape, Kwa-Zulu Natal and the Free State were the provinces with the highest GHG emission profiles, incorporating all species, producing 24.3%, 15.3% and 14.9% of the total national emissions.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Linde du Toit on linde.dutoit@up.ac.za