Meat inspection of pigs slaughtered in Norwegian abattoirs: insights from variance partitioning analysis

Routinely recorded meat inspection data represent a valuable source of information for animal health and welfare surveillance. However, their utility for secondary purposes depends on data quality and the consistency of recorded findings. This study aims to describe the data recorded during the slaughter process for Norwegian pigs, the feasibility of combining datasets, and estimate the contribution of farm, abattoir, and external factors to the overall variation in recorded findings, using meat inspection records from October 2021 to March 2024 from 15 abattoirs, comprising 75 828 batches. Meat inspection data are recorded at three stages of the pig slaughter process, resulting in three separate databases. Merging of these datasets was not possible at the individual pig level with adequate completeness, and substantial manual data processing was required to combine data at the batch level. Post-mortem inspection is conducted at two stages: routine inspection of all carcasses, recorded as “extended disease registrations” (EDR) and assessment of carcasses suspected of requiring condemnation, documented as “post-mortem findings”. The variation in the most frequent EDR findings and post-mortem findings was estimated using variance partitioning. EDR findings showed low variation between abattoirs, particularly for “pericarditis and/or pleuritis” and “open tail wounds”, suggesting consistent detection between abattoirs. In contrast, the post-mortem findings «systemic disease», “abscesses/phlegmons” and “gastrointestinal disease” showed substantial abattoir-level variance, indicating inconsistencies in recording practices. Season had minimal effect on the variance components, while day of week only affected the post-mortem finding «gastrointestinal disease». EDR findings were consistently detected across abattoirs, suggesting their potential as a reliable source for animal health and welfare surveillance. In contrast, substantial variation in certain post-mortem findings highlights the need for harmonization and standardization of recording practices. Future improvements in data quality and traceability are essential for robust secondary use of meat inspection data in surveillance.