According to regulation (EC) No. 854/2004 all pigs slaughtered in Austria are subject to a routine meat inspection at the slaughterhouse in order to detect pathological-anatomical organ alterations due to disease. This mandatory meat inspection constitutes an important contribution to ensure food safety and the resulting post-mortem findings provide a possibility to process optimization by reporting the routinely recorded results to the producers. We analyzed the impact of 18 post-mortem findings on the average daily net gain of 6119 pigs. All findings were recorded at an Austrian slaughterhouse within a quality assurance system. A linear mixed model (LMM) was applied incorporating the farm of origin as random effect in order to take non-observed farm specific risk factors (e. g. feed management, housing system, hygiene status) into account. As a result the expected average daily net gain of 490 g could be estimated and several post-mortem findings could be identified as significant factors (at the significance level 0.05) affecting the average daily net gain. The expected average daily net gain decreases significantly for pigs with at least one of the post-mortem findings arthritis (-64 g), abscess (-32 g), severe pneumonia (-13 g), visceralis pleuritis (-7 g) and hepatitis (-9 g). The expected average daily net gain increases by 5 g for pigs with post-mortem finding bursitis. The estimated random farm effect indicates the relevant impact of the farm environment on the average daily net gain. The results reinforce that there is still a great potential to improve efficiency in fattening, although the quality assurance system was implemented twelve years ago.