Optimizing Swine Oral Fluid Sampling Procedures for Growing Pigs in Commercial Settings

Pen-based oral fluids are used extensively for surveillance and disease detection in swine, but there is sparse information on the sampling process itself. To address this shortcoming, we documented the pen-based oral fluid sampling process with the aim of optimizing the number of pigs in a pen that contributed to the sample. We quantified the effects of (1) previous experience with rope sampling (training), (2) the number of ropes suspended in the pen, and (3) sampling time on pig participation and pig-rope contact. A subset of pigs was clearly marked for individual identification and their interactions with ropes video recorded. Thereafter, pig-rope contacts were counted from the recordings, with "contact" defined as an individually identified pig clearly taking the rope into its mouth. Data were analyzed using appropriate models (R version 4.4.1 R core team 2024). Training, provision of additional ropes, and extended sampling time all increased pig participation across pen sizes. However, for routine oral fluid collection in the field, we recommend training pigs prior to hanging ropes for sample collection and increasing sampling time to maximize the pigs' contribution to the oral fluid sample. Importantly, these studies focused on pig behavior and not detection; thus, future studies should evaluate the impact of these same factors on the probability of detection.