A simplified evaluation system of surface-related lung lesions of pigs for official meat inspection under industrial slaughter conditions in Germany

Background: European and national administrative legislation require objective evaluation systems for organ lesions at pig slaughter. These results can be used as basis for herd health improvement programs by farmers and their consulting veterinarians. Various studies have shown that the current evaluation and recording of lesions by authorized meat inspectors are not reliable and produce significant inter-rater disagreement especially for lung lesions in pigs. The objectives of this study were to increase the usability of official meat inspection data by a developed and validated scheme and to analyze potential improvements in the reliability of the proposed system under industrialized slaughter conditions. Results: A simplified evaluation scheme for surface-related lung lesions was developed based on morphometric evaluations of unaffected lungs with quantitative relationships of each lobe to the whole lung ("Rule of Tens"). Furthermore, a theoretical as well as a hands-on training program for meat inspectors was developed and applied. Based on 5,183 lungs, the authors established a baseline of the inter-rater reliability of current routine assessments of lung lesions as documented by meat inspectors compared with the assessments of an independent veterinarian using the developed simplified evaluation scheme. Most frequent inter-rater disagreements greater than 75% were found for moderate pneumonia. Sources of the deviations most frequently included misinterpretations of technical artifacts, which were erroneously assessed by the meat inspectors as pneumonic lung lesions. Results of the post-training investigation based on 4,646 lungs showed a significantly improved reliability of lung lesion evaluation and the inter-rater agreement increased in all respects. Especially the disagreement of recording moderate cases of pneumonia decreased in total to 15% deviations from reference. Conclusions: The presented simplified lung evaluation scheme showed its capability to standardize the evaluation of lung lesions according to administrative legislation under industrialial slaughter conditions. The reliability of official meat inspections can be significantly increased with the help of the presented scheme to assess surface-related lung lesions of slaughter pigs. Continuous standardization and optimization can be achieved by personalized training programs in the framework of quality assurance systems for meat inspectors.