Describing the cull sow market network in the US: A pilot project.

Currently, little objective data is available describing the movements of cull sows and cull pigs through market channels or the association these movements with disease transmission risk. In this pilot study, we collected data to describe the scope and complexity of movements within the sow market channel. Premise ID tags where collected from all animals moving through a single slaughter plant over a one-week period in 2017. The premise ID's were each cross referenced with a public database to obtain origin location, and each tag was matched with its final collection point (FCP). This allowed terminal market, FCP, and point of origin of each sow to be determined. Approximately 90.4% of all sows moving to the plant during the one-week period were identified, indicating the utility of this data collection approach. Sows originated from premises in 21 states and Canada, and shipped from collection points in 7 states and Canada. Sows traveled a median straight-line distance of 1057 km, identifying the national scope of the sow market. Of the sows identified, 86% entered the plant from a final shipping point that was within 240 km to the source farm. The remaining 14% traveled more than 240 km from the premise of origin to the final point of shipment with 2.5% traveling distances 5 times greater between premise and FCP, then from FCP to the plant. From this it was hypothesized that not only is the sow market national in scope, but a significant number of sows are moved between multiple collection points prior to arriving at the terminal market. The combination of these two factors makes the sow network a likely candidate of pathogen transmission throughout the swine industry.