The effects of group size and subtherapeutic antibiotic alternatives on growth performance and morbidity of nursery pigs: a model for feed additive evaluation

Olsen, Kristin M; Gabler, Nicholas K; Rademacher, Chris J; Schwartz, Kent J; Schweer, Wesley P; Gourley, Gene G; Patience, John F

were transferred to a plastic tube and stored at −20 °C until analysis. Oral fluid samples were analyzed using polymerase chain reaction (PCR) for PRRSV, Influenza type-A virus of swine (IAV-S), porcine epidemic diarrhea virus (PEDV), porcine deltacoronovirus (PDCoV), and M. hyopneumoniae. Oral fluid samples were also collected from four pens exhibiting clinical symptoms (coughing, sneezing, lethargy) and tested for PRRSV and IAV-S on day 26. Blood samples were collected from one pig per pen in two pens per dietary treatment (using the same pens as oral fluid collections) for a total of eight blood samples on days 1 and 28. At the end of the trial (day 41), eight pigs per dietary treatment (one pig from each of the large pens) were euthanized for a separate experiment and blood was collected from each. Ten milliliters of blood were collected by jugular venipuncture and centrifuged at 2,000 × g for 10 min at 4 °C, and the resulting serum was stored at −80 °C for later analysis. Serum samples from day 41 were tested for PEDV and M. hyopneumoniae using PCR. The goal of this diagnostic testing was to establish a general knowledge of disease exposure and health status of the pigs used in the study.