Environmental impact trade-offs in diet formulation for broiler production systems in the UK and USA

The environmental impacts associated with broiler production arise mainly from the production and consumption of feed. The aim was to develop a tool for formulating broiler diets designed to target and reduce individually specific environmental impact categories in two contrasting regions, the UK and USA. Using linear programming, least cost broiler diets were formulated for each region, using the most common genotype specific to each region. The environmental impact of the systems was defined using 6 categories calculated through a Life Cycle Assessment (LCA) method: global warming potential (GWP), fresh water eutrophication potential (FWEP), marine eutrophication potential (MEP), terrestrial acidification potential (TAP), non-renewable energy use (NREU) and agricultural land use (ALU). Diets were then formulated for each region to minimise each impact category, without compromising bird performance. The diets formulated for environmental impact objectives increased their cost in most cases by between 20 and 30% (the cost increase limit), with the exception of the least GWP (+ 16%) and the least NREU (+ 4%) diets in the UK, and the least TAP diet in the USA (+ 14%). The degree of flexibility to reduce simultaneously several environmental impact categories in the UK and the USA differed due to the different feed ingredients available to each region. The results suggested there was potential to minimise several impact categories simultaneously by reducing the impact of one impact category compared to least cost, through diet formulation in the UK; this was shown to a greater and lesser extent in the least FWEP and the least NREU diet formulations respectively. In the USA, there was no way to minimise one impact category through diet formulation without increasing other impact categories caused by the system. Employing a multi-criteria approach to diet formulation methodologies, where environmental impact as well as economic implications are considered, will form an important pillar in broader efforts to improve the sustainability of animal production.