Changes in the environmental impacts of pig production systems in Great Britain over the last 18 years

Abstract

ContextThe aims of global pig production systems include a reduction of their environmental impacts, which can be achieved through an increase in outputs whilst minimising inputs. ObjectiveThe aim of this paper was to develop a novel method to enable estimation of the changes in the environmental impacts based on sparse data from the British pig production industry over ~20 years. MethodsTo achieve this, we developed a Life Cycle Assessment (LCA) method capable of dealing with sparse historical data from livestock systems. We applied it, for the first time, to estimate the temporal changes in environmental impacts of British pig production systems caused by changes in production performance. Performance data available from industry-held databases for indoor and outdoor bred pigs in Britain were used to estimate nutrient requirements through animal performance modelling, and feed composition through least-cost formulation. The cradle to farm-gate LCA model developed, included manure management and the full life cycle of the pigs and its functional unit was 1 kg of live weight pig at farm-gate. Sensitivity analyses were conducted to investigate the potential influence of changes in animal performance and feed prices on the estimated changes in environmental impacts. Results and ConclusionsThe higher growth rates and increased leanness over the period considered led to substantial reductions in energy requirements. Overall, the system changes led to reductions, for indoor and outdoor bred systems respectively, of 37.0% and 35.4% for Global Warming Potential, 21.2% and 16.4% in Terrestrial Acidification Potential, 22.5% and 22.3% in Freshwater Eutrophication Potential, 15.8% and 16.8% in Agricultural Land Use and 16.5% and 16.1% in Fossil Resource Scarcity. The sensitivity analyses showed that trends in feed composition were influential on the environmental impact outcomes, and that the LCA model was more sensitive to the change in feed composition than to the changes in animal performance over the time period considered. SignificanceKnowledge of temporal changes to the environmental impacts of livestock systems and the drivers of changes to date should guide future decisions to mitigate these impacts.