Life-cycle assessment of pasture- and grassland-based milk production systems

As part of the project 'Optimisation of Grassland-Based Milk Production Systems based on Fresh-Grass Harvesting (Hohenrain II)', we used the SALCA life-cycle assessment method to compare the environmental impacts of three systems, viz. full-grazing with seasonal calving and two variants of fresh-grass harvesting with differing use of concentrates (<500 kg/cow/ year and 800-1200 kg/cow/year). Systems using higher amounts of concentrates had higher, and hence less favourable, scores in the 'potassium resource demand' and 'ecotoxicity' categories, as well as in the 'phosphorus resource demand' and 'deforestation' categories in some instances, than systems using lower amounts of concentrates. By contrast, for 'global warming potential', 'ozone formation' and 'landscape aesthetics', the system using higher amounts of concentrates in some cases had more favourable scores than the full-grazing system. In several additional impact categories there were no obvious differences between the systems, owing to the high variability between the farms and years investigated. The main factors influencing the environmental impact of milk were feed conversion (kg feed/kg energy-corrected milk [ECM]), composition of the feed ration, concentrate intake, cattle restocking, and fertiliser application.