Table 1 Overview of the registers used in this study

Norwegian Livestock Register

Norwegian Food Safety Authority

Information about pig movements (batches) between agricultural holdings and to slaughter. Each record includes the date, sender, receiver, number of pigs, and the purpose of movement. Reports are sent by receiving farms or slaughterhouses.

Number, type, and direction of pig movements per farm

Register for Production Subsidies

Norwegian Agricultural Agency

Information from voluntary applications for production grants to agricultural holdings. For each holding, the register includes the name, report date, and number animals per category. Counts for pigs are reported twice per year.

Number of pigs per farm

Register for Carcass Deliveries

Norwegian Agricultural Agency

Deliveries of livestock for trade, slaughter and wool from agricultural holdings. For each holding, the register includes the name, date, municipality, number traded or slaughtered, and animal information (weight, type). Pig reports are at the individual-level.

Number of traded and slaughtered pigs per farm

HelseGris

Animalia

Industry-owned documentation system for health, welfare, and biosecurity for pig farms.

Production category for farms