THE ADVENT OF "GREEN" CATTLE
Livestock farming is often dismissed as irredeemably inefficient and polluting. But that was before anyone thought of considering a cattle herd as a diverse group of animals
Implications of livestock farming on climate change should not be drawn from aggregate statistics, reveals a study based on a new method of carbon footprinting for pasture-based cattle production systems that can assess the impacts of individual animals.
The new method, developed by a team from Rothamsted Research and the University of Bristol, records the environmental impact of each animal separately before calculating the overall burden of a farm.
Existing methods of carbon footprinting are primarily designed to quantify total greenhouse gas (GHG) emissions of a particular farm, and are therefore unable to provide information on environmental performances of specific animals.
The ability to identify “green” cattle within a herd – cattle that produce lower emissions per kilogram of liveweight gain – promises more sustainable farming, they report in the study published today in the Journal of Cleaner Production.
The team applied both the new and old methods to field data collected at the North Wyke Farm Platform (NWFP), a Rothamsted state-of-the-art facility that supports three experimental farms over 63 hectares in Devon.
They demonstrated that the latter approach consistently underestimates levels of GHG emissions because it fails to consider sufficiently the impacts of poorly performing animals, which are known to produce disproportionally large amounts of methane through enteric fermentation.
“The research offers two important lessons that may seem paradoxical at first sight,” says Taro Takahashi, Research Scientist at North Wyke and Senior Lecturer in Sustainable Livestock Systems and Food Security at Bristol Veterinary School, who led the research.
“Short-term, many carbon footprint estimates currently available are probably too low, which is clearly bad news for the industry. But long-term, this also means that mitigation of greenhouse gas emissions originating from ruminants could be easier than traditionally thought—if we are able to select the right animals through the right screening methods. And this is precisely what we are trying to achieve at North Wyke.”
The work also marked the first comprehensive evaluation of the three production systems at North Wyke. “This study demonstrates the true value of primary data being collected by the NWFP team every day,” says Paul Harris, the facility’s project leader. “They can challenge our intuition and enhance our understanding of how we can make agriculture more sustainable.”
The new study comes as the debate about the role of livestock in sustainable global food production intensifies. In a report published this month, the Food Climate Research Network (FCRN) reiterated that livestock production is a net contributor to global warming regardless of the species and the rearing method.
“We agree with the FCRN report that ruminants cannot reverse climate change, even if they are grass-fed,” says Michael Lee, Head of North Wyke and Professor of Sustainable Livestock Systems at Bristol Veterinary School. “However, as we discussed in our 2014 article in Nature, pasture-based livestock production systems have a multifaceted role in society – the point acknowledged, but not actively addressed, by the FCRN report.
“At Rothamsted, not only do we aim to advance knowledge on how to minimise negative impacts of agricultural production, as exemplified by the current paper, but also on how to optimise the positive contribution grazing livestock can bring to us as part of a well-designed food supply chain.”
Lee adds: “Such aspects include effective use of land unsuitable for growing crops, production of higher quality protein and more bioavailable micronutrients, improved animal welfare, prosperous rural communities and flood prevention. They all make up the bigger picture when looking for a sustainable future of food production.”
NWFP is a UK National Capability funded by the Biotechnology and Biological Sciences Research Council (BBSRC). Its datasets and resources are open to all researchers, including those outside Rothamsted. The research was funded by the Agriculture and Horticulture Development Board (AHDB) and by the Department for Environment, Food and Rural Affairs (Defra) through the Sustainable Intensification Research Platform (SIP).
About Bristol Veterinary School, University of Bristol
The Bristol Veterinary School's research is focused in the areas of Animal Welfare and Behaviour, Comparative and Clinical Research, and Infection and Immunity (including Veterinary Public Health), and the research in all three groups is underpinned by the themes of Global Food Security and Antimicrobial Resistance.
Research ranges from fundamental to applied and is relevant to over-arching issues such as Food Security and One Health, concepts that the School's research embraces through collaborations with scientists from other schools within the Faculties of Health Sciences and Science and other regional institutes and organisations.
The University of Bristol is at the cutting edge of global research and has made innovations in areas ranging from cot death prevention to nanotechnology. Founded in 1876, the University is one of the most successful and popular in the UK and was ranked within the top 50 universities in the world in the QS World University Rankings 2018.
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About Rothamsted Research
Rothamsted Research is the oldest agricultural research institute in the world. We work from gene to field with a proud history of ground-breaking discoveries. Our founders, in 1843, were the pioneers of modern agriculture, and we are known for our imaginative science and our collaborative influence on fresh thinking and farming practices.
Through independent science and innovation, we make significant contributions to improving agri-food systems in the UK and internationally. In terms of its economic contribution, the cumulative impact of our work in the UK exceeds £3000 million a year1. Our strength lies in our systems approach, which combines science and strategic research, interdisciplinary teams and partnerships.
Rothamsted is also home to three unique resources. These National Capabilities are open to researchers from all over the world: The Long-Term Experiments, Rothamsted Insect Survey and the North Wyke Farm Platform.
We are strategically funded by the Biotechnology and Biological Sciences Research Council (BBSRC), with additional support from other national and international funding streams, and from industry.
For more information about Rothamsted.
BBSRC invests in world-class bioscience research and training on behalf of the UK public. Our aim is to further scientific knowledge, to promote economic growth, wealth and job creation and to improve quality of life in the UK and beyond.
Funded by Government, BBSRC invested over £469M in world-class bioscience in 2016-17. We support research and training in universities and strategically funded institutes. BBSRC research and the people we fund are helping society to meet major challenges, including food security, green energy and healthier, longer lives. Our investments underpin important UK economic sectors, such as farming, food, industrial biotechnology and pharmaceuticals.
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