The present study contributes to evaluate the environmental impacts associated with the dairy sector in Mainland Portugal. For that purpose, Life Cycle Assessment (LCA) was used as an environmental management tool. The environmental impacts associated with UHT milk, curd cheese and yoghurt were estimated over their life cycle, which includes dairy farm, industry, transport, chemical production and energy production systems.

The result of the quantification of the environmental impacts of the dairy farms in Mainland Portugal in year 2005 was 4.9 thousand tons of Sb eq year^-1 for the abiotic depletion potential, 1813 ktons of CO₂ eq year^-1 for the global warming potential, 508 tons of C₂H₄ eq year^-1 for the potential formation of photochemical oxidants, 27.5 thousand tons of SO₂ eq year^-1 for the acidification potential and 8.9 thousand tons of PO₄^3- eq year^-1 for the eutrophication potential. The majority of these impacts were caused by the dairy farm and the industrial systems. The dairy farm was the main responsible for global warming (57%), acidification (77%) and eutrophication (84%), whereas the milk industry had the main contribution for the depletion of the abiotic resources (48%) and the formation of photochemical oxidants (5%).

In the UHT milk subsector, the majority of the environmental impacts were due to the activities taken place in the farms and in the milk production industry. On the other hand, in the curd cheese subsector, the cheese production industry is only the main responsible for the acidification and eutrophication categories. Finally, for the yoghurt subsector, the activities associated to the yogurt production industry contribute less than 10% for all the impact categories.

This study provides useful information that can assist the dairy industry in identifying the main environmental impacts and their sources, allowing the industry to improve its environmental performance, not only at the mill level but also on the other systems along the production chain.