The advent of "green” cattle

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.