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.

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A new study reveals that the implications of livestock farming on climate change should not be drawn from aggregate statistics, based on a new method of carbon foot printing 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 foot printing 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 live weight gain - promises more sustainable farming, according to a study published 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 older methods consistently underestimate 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.

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, 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.”

Paul Harris, the facility’s project leader says 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. 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.

NWFP is a UK National Capability funded by 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).