The advent of “green” cattle
Press release issued: 30 October 2017
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 the University of Bristol and Rothamsted Research, 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.
Dr Taro Takahashi, Senior Lecturer in Sustainable Livestock Systems and Food Security at Bristol Veterinary School and Research Scientist at North Wyke, who led the research, said: "The research offers two important lessons that may seem paradoxical at first sight.
"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," added 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," said Michael Lee, Professor of Sustainable Livestock Systems at Bristol Veterinary School amd Head of North Wyke. "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."
Professor Lee added: "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).
'Distributions of emissions intensity for individual beef cattle reared on pasture-based production systems' by McAuliffe G.A., Takahashi T., Orr R.J., Harris P., Lee M.R.F. (2017) in Journal of Cleaner Production [open access]
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 year (Rothamsted Research and the Value of Excellence, by Séan Rickard, 2015). 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, visit https://www.rothamsted.ac.uk/
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