The environmental assessment of a pig farming system from a cradle-to-farm gate perspective was carried out in this study. To do so, two separated farms destined to the weaning and fattening of pigs were analysed in Galicia (Northwest Spain). The standard framework of the Life Cycle Assessment (LCA) was followed to assess the environmental performance of the global process. Six impact categories were selected, including climate change (CC), terrestrial acidification (TA), freshwater eutrophication (FE), marine eutrophication (ME), agricultural land occupation (ALO) and fossil depletion (FD). The edible protein energy return on investment ratio (ep-EROI) was also considered. The fattening farm related activities were the main contributor to the global environmental burdens in almost all impact categories, with contributions higher than 72%. Both concentrate feed production and on-farm emissions were detected as the principal hotspots, mainly due to the burdens associated with concentrate feed ingredients production as well as those derived from the manure management process, respectively. The characterisation results in terms of CC (3.4 kg CO2 eq), FD (12.5 MJ) and ALO (5.0 m2 yr) were consistent with similar European LCA studies on pigmeat production while uncertainty in LCA choices was the main responsible of minor variability on TA, FE and ME. The ep-EROI value (7.3%) was also in line with published data. Due to the relevance of concentrate feed production on the global environmental profile, several feeding strategies were proposed as potential environmental improvements, of which the introduction of local ingredients seemed the most promising alternative.