You are here

  1. Home
  2. GHG reductions from livestock

GHG reductions from livestock

Work Package Livestock production, health, welfare and disease control

Research Deliverable 
GHG reductions from livestock

Introduction

There are challenging national and global targets to reduce greenhouse gas (GHG) emissions, including from livestock production. The coordinated programme of research conducted by the UK GHG Research Platform (completed in 2015) resulted in a much clearer picture of emissions and mitigation opportunities from UK livestock farming. This work will build on that project, filling some of the remaining gaps in information. A wide range of production systems, livestock classes and feed types were studied by the GHG Platform, though data from studies with fresh herbage and grazing animals remain limited. There is considerable unexplained variation in GHG emissions from livestock grazing herbage and this is a serious knowledge gap given the importance of grazing to sheep and cattle systems in Scotland. Other research has identified considerable animal genetic variation in methane emissions, though progress in exploitation will be slow because of the difficulty of making measurements with sufficient animals. Work on grazing effects and genetics of GHG emissions will accelerate if we can identify suitable proxies for GHG emissions, or other low cost/rapid methods based on samples that are easy to collect from large numbers of animals. There is a need to study the role of endemic disease (those diseases present within the UK here and now) on production efficiency and GHG emissions from livestock – this will be explored in a Scottish context. In addition to the requirement to fill information gaps on specific mitigation options, there is a growing need to explore synergies and antagonisms when applying combinations of mitigation options.

Aim of Research

Animal-based strategies to reduce greenhouse gas emissions from ruminant livestock: The aim of this work is to address major knowledge gaps in greenhouse gas (GHG) emissions from livestock by investigating the effects of different grassland management systems, the rumen microbiome (the microbes that normally inhabit the gut), endemic diseases and host genetics on methane production and emissions intensity.

Progress

2021 / 2022
2021 / 2022

Work in this final year focussed on consolidation and dissemination of information. Key outputs include a paper identifying NMR based chemical proxies for methane emissions and detailed modelling work continued to describe relationships between metabolites, microbial species and genes in the rumen, in order to further improve prediction of methane emissions. An R package for simulating methane production rate based on dry matter intake rate using a mechanistic model of the rumen is publicly available at: https://github.com/HelenKettle/Rumen  We have engaged extensively with key livestock sector stakeholders to produce a priority list of sheep and cattle diseases and syndromes affecting greenhouse gas emissions and this information is presented in a report, along with mitigation options and practical intervention strategies (https://ruminanthw.org.uk/actingonmethane/) . We have also provided empirical evidence on the production impacts and implications for greenhouse gas emissions associated with gastrointestinal parasitism in sheep and liver fluke infection in cattle. A study in which non-parasitised lambs were offered their daily ration in small portions (representing the lower feed intake and gut fill seen in parasitised lambs), or with unrestricted access to their complete ration (representing the intake of non-parasitised lambs) showed that impacts of parasitism on methane emissions are not driven by changes in feeding behaviour. Work on rumen volume as a proxy for methane emissions continued with analysis and publication of rumen volumes from archived measurements from 5 different terminal sire sheep breeds, as well as new measurements of feed intakes and rumen volumes of further lambs.

2020 / 2021
2020 / 2021

The ability to breed for low emitting ruminants will depend on low-cost proxies that can be implemented on-farm. Our studies have evaluated the analysis of rumen fluid for metabolites, microbial species or microbial genes and shown that we can explain a similar level of variation in methane emissions using any one of these measurements. Current work is advancing understanding and looking for improved predictions by exploring the relationships between metabolites, species and genes. Other work has developed an alternative proxy approach through the use of computerised tomography (CT) scanning. Earlier we showed that low methane emitters have smaller rumens and in the last year have explored possible genetic correlations between rumen volume and other animal production and carcase traits. we need to avoid negative genetic correlations with methane emissions because aspects of technical efficiency, such as feed efficiency and health traits, also affect GHG emissions intensity. Detailed statistical analysis of Scottish cattle abattoir data revealed that animals with active liver fluke infection gained 17g/day less saleable beef and were 11 days older than animals with no obvious fluke. Calculation of the associated GHG emissions suggests the carbon footprint of meat from a herd with no fluke is approximately 1.5% lower than the same herd with fluke.

2019 / 2020
2019 / 2020

Work on methane proxies has identified a range of tools that can be used to predict methane emissions under different conditions and measurement constraints; these are now starting to be used to generate genetic parameters for methane emissions. In situations where it is possible to obtain samples of rumen fluid, we can use proxies based on metabolites or gene abundances. In other situations, it may be more useful to use the proxy based on estimates of rumen volume from CT scans that can be conducted alongside scanning for other sheep breeding purposes. Work on metagenomic predictors of methane emissions is now being incorporated into mechanistic and time-series models. Broader system modelling using large-scale abattoir datasets has quantified the important effects of parasites and parasite control strategies on greenhouse gas emissions intensities. This year we undertook a study to determine the potential for extending the use of rumen gene abundance as a proxy for methane output to cattle at grazing. Housed cattle were either offered a diet of fresh cut grass or a high concentrate diet. Methane output was measured in respiration chambers and rumen samples were obtained and sequenced. Significant differences in gene abundances and methane output between these two extreme diets indicating high potential for the use of rumen gene abundances as a proxy for methane output. We have been investigating the impact of liver fluke and GI nematodes on cattle, using large-scale abattoir datasets. Both studies showed effects on liveweight gain and days to slaughter, affecting GHG emissions, and that these effects could be mitigated by sustainable parasite control strategies. The rumen volume measurement technique was applied to historical images obtained from 671 commercial Texel lambs during routine scanning and demonstrated that the trait is moderately heritable.

2018 / 2019
2018 / 2019

We are making considerable progress in development of both improved models and proxy methods for predicting methane emissions from ruminants. A session at the British Society of Animal Science Annual Meeting on 'Models and proxies for methane emissions from ruminants' held at the end of year 3 (April 2019, Edinburgh) (https://bsas.org.uk/) was dominated by work from this programme. Models presented ranged from mechanistic models of rumen metabolism through to analysis of emission patterns related to meal patterns. Proxy techniques include estimates based on measurements of rumen metabolites, rumen microbial communities and genes and rumen volume (estimated using X-ray CT scanning). There is a great potential for synergy between these approaches during the next phase of work. Other work is modelling the effect of key animal disease and disease control practices on GHG emissions intensity, based on data derived from the Scottish livestock sector. A further series of measurements of methane emissions from beef cattle offered grass silage-based diets was completed; half of these animals were supplemented with a natural oil-based additive to investigate its effect on methane emissions. The data-based model for methane production rate from dry matter intake or intake time has now been published and we are applying the same approach with other data sets. Similarly, the relationship established between rumen volume and methane emissions are being explored further using new and library CT scans; we have started to explore within-breed genetic variation in rumen volume.

2017 / 2018
2017 / 2018

We continue to show the potential of several exciting proxies for methane emissions which could be used in breeding programmes - including estimates of rumen volume (by CT scanning), breath methane concentrations (from the laser methane detector), rumen metabolites (using NMR spectroscopy), intake times (using animal behaviour monitors) and the abundances of genes in rumen microbes. Measurements of methane emissions using respiration chambers underpin all of this work, though success in developing proxies offers the potential to conduct future work with grazing cattle. In addition to targeting methane emissions directly, we continue to collect and model data looking at the effects of animal health and efficiency on methane emissions per unit of milk and meat produced. A series of measurements of methane emissions from beef cattle offered either grass silage- or red clover silage-based diets was completed.  This study provided samples for ongoing analysis of the feasibility of using rumen metabolites and/or rumen gene abundances as proxies for methane emissions. Time series data from respiration chamber experiments on the effects of diet on methane emissions from cattle have been used to develop a novel model to predict emissions based on the time animals spend eating. The CT scanning studies confirmed a positive relationship between the volume of the first of the sheep’s four ‘stomachs’ (the rumen) and methane emissions. We have assembled data for key endemic diseases, specifically looking at effects of liver fluke and gastrointestinal nematodes (stomach worms) on the productivity and GHG emissions intensity of cattle.

Highlights:

  • An increasingly important part of our work to reduce GHG emissions intensity is through promoting technologies to improve efficiency and health. The SRUC stand at the Royal Highland Show featured our work to develop and promote precision agriculture technologies and GHG research was featured at an Open Day held at SRUC Barony Campus (Dumfries). Over 100 Aberdeen Angus breeders visited the GreenCow facility and toured displays about measurement and reduction of methane emissions through diet changes and breeding.
  • Student presentation 'Nuclear Magnetic Resonance to identify rumen metabolites as proxies for methane emissions' at the final meeting of the EU-funded COST action ‘Methagene’ at Caserta (Italy) was a valuable forum for discussion of proxies emerging from work at SRUC and elsewhere.
  • Further set of methane measurements were completed through the SRUC GreenCow facility.
  • Information on incidence of key diseases (liver fluke, gastrointestinal nematodes & Bovine Viral Diarrhoea) being extracted from relevant abattoir and national surveillance datasets. The impact of control measures is being evaluated from both scientific and non-scientific literature.
  • Data has been analysed relating rumen characteristics to methane emissions. The total volume of the rumen significantly affected dry matter intake and methane emissions (per day or per unit of dry matter intake) from ewes.
2016 / 2017
2016 / 2017

Experimental work is underpinned by mathematical modelling of methane emissions measured using the gold standard method of respiration chambers. The rumen model was been expanded to include several more processes, such as the circulation of gas in the respiration chamber and the transport of gas from the rumen into the blood stream. We have made good progress in other statistical modelling of methane emissions based on measurements of rumen metabolites and microbial communities and will continue to develop this analysis using existing stored samples. This analysis will enable us to develop simple proxies for methane emissions to support breeding of low methane emitting cattle or sheep. Work to explore relationships between rumen characteristics, measured by CT scanning, and methane emissions was commenced with collection of CT images of rumens from 99 ewes. Other work is developing our understanding of the key role of animal health/treatments and feed conversion efficiency in reducing greenhouse gas emissions intensity without targeting directly rumen methane emissions. We have assessed the role of animal health in reducing the production efficiency of livestock, identified parameters that GHG emissions are sensitive to and produced a priority list of endemic diseases in discussion with Scottish Government policy teams and key industry stakeholders. Work is ongoing to quantify the impact of individual diseases e.g. liver fluke and parasitic worms on GHG emissions. This work has helped inform the SG draft Climate Change Plan for Agriculture.

Highlights:

  • The rumen methane production model has been updated to include a number of new bio-chemical and physical processes and microbial groups.
  • A combination of literature searching and expert opinion has been used to help prioritise sheep and cattle diseases for further analysis. A meeting of key livestock sector stakeholders was held at Moredun to discuss sheep and cattle disease priorities, knowledge gaps and next steps.
  • GHG research from a previous Scottish Government-funded work programme continued to be profiled at events and exhibits organised by both Moredun Research Institute and SRUC. SRUC GHG research was presented at the Easter Bush Campus Open Day, which provided a good opportunity to engage with interested members of the public (approx. 500 attendees).
  • Rumen volumes (by CT scanning) and methane emissions (respiration chambers) were recorded for approx. 100 ewes.

Future Activities

Future work on measurement and proxies for methane emissions from cattle, will be extended to consider methane emissions from animals at grazing. We are exploring options for animal-mounted methane measuring equipment. We are working on a paper about the genetics of rumen volume and will investigate links between rumen volumes and EBVs across different terminal sire breeds. Other work will explore relationships between methane proxies (rumen volume) and feed efficiency.

Modelling work linking animal health and GHG emissions is now focussing more on BVD, with strong links with the Scottish Government’s BVD Eradication Scheme policy team. Work is continuing to identify the impact of BVD on production and associated GHGs in Persistently Infected (PI) cattle and their contemporaries.

Moredun Institute will host the 2nd SEFARI Livestock Health & GHG workshop in September 2021.

Selected Outputs

  • Lambe, N.R., Miller, G., McLean, K.A., Gordon, J. and Dewhurst, R.J. (2019). Prediction of methane emissions in sheep using computed tomography (CT) measurements of rumen volume. Proceedings of the British Society of Animal Science, April 2019, Edinburgh . doi 10.1017/S2040470019000013
  • Vrancken, H., Suenkel, M., Hargreaves, P.R, Chew, L. and Towers, E. (2019). Reduction of Enteric Methane Emission in a Commercial Dairy Farm by a Novel Feed Supplement. Open Journal of Animal Sciences 9: 286-296. (http://www.scirp.org/journal/ojas)
  • Hargreaves, P.R., March, M.D. and Dewhurst, R.J. (2019). Effect of antibiotic treatments on dairy cow methane production, milk yield and dry matter intake. BSAS Annual Conference in Edinburgh, 9-11 April 2019.
  • Brocklehurst, S., Hargreaves, P.R. and March, M.D. (2019). Novel statistical methods to improve analysis of laser methane detector data. BSAS Annual Conference in Edinburgh, 9-11 April 2019.
  • Hargreaves, P.R., Sünkel, M. and Towers, E. (2019). Impact of a garlic-citrus powder on methane emissions and performance on Dairy Cows in real farm conditions. XIIIth International Symposium on Ruminant Physiology, Leipzig, Germany, 3-6 September 2019.
  • And an appearance on Broader TV – Border Life – Use of Laser Methane Detector and the Langhill Herd:
  • Blog by Philip Skuce and Michael Macleod: https://sefari.scot/blog/2019/04/08/livestock-health-and-greenhouse-gases-ruminating-on-climate-change
  • Lambe NR, McLaren A, McLean KA, Gordon J, Conington J (2020) Could rumen volumes measured by CT scanning help to breed sheep with lower methane emissions? Proceedings of the 71st Annual Meeting of the European Federation of Animal Science.
  • Kipling, RP, Bannink, A, Bartley, DJ, Blanco-Penedo, I, Faverdin, F, Graux, A-I, Hutchings, NJ, Kyriazakis, I, Macleod, M, Østergaard, S, Robinson, TP, Vitali, A, Vosough Ahmadi, B and   Özkan, S (2021). Short communication: Identifying key parameters for modelling the impacts of livestock health conditions on greenhouse gas emissions. Animal 15: 100023.
  • Texel Bulletin article: "Breeding for lower methane emissions"  
  • Texel Bulletin article: "GrassToGas: Strategies to mitigate greenhouse gas emissions from pasture-based sheep systems (G2G)."
  • Eastbio on-line student seminar "Tools to breed sheep with lower methane emissions"     
  • SAC Consulting webinar: Future Livestock - Climate change "Grass to Gas: Strategies to mitigate GHG emissions from pasture-based sheep systems"
  • Farming for 1.5-degree Committee "Prospects for reducing GHG emissions from sheep via genetic improvement"             

Research Deliverable Lead

Professor Richard Dewhurst

View Profile
Get in touch