Assessment of nebulization technology for gilt exposure to Mycoplasma hyopneumoniae as an acclimation strategy

Objective: This study assessed the efficacy of nebulization (NEB), also known as fogging, to expose gilts to Mycoplasma hyopneumoniae under field conditions as a potential acclimation strategy. Materials and methods: Phase I consisted of 448 M hyopneumoniae-free gilts from four different batches of a gilt development unit (GDU). On study day 0, batches 1 and 2 were exposed to M hyopneumoniae-positive lung homogenate via intratracheal (IT) route and were used as reference for batches 3 and 4, which were exposed using a mechanical fogger. Tracheobronchial swabs (TBS) were collected at 2 and 4 weeks post exposure (D14 and D28, respectively) and infection success was assessed by real-time polymerase chain reaction of pooled samples. In phase II, 1160 gilts from the same GDU belonging to three different batches (5 to 7) were exposed to M hyopneumoniae via NEB, and TBS were collected at D14. Results: In phase I, no statistically significant differences were observed between IT and NEB exposure in proportion of positives and mean cycle threshold values of TBS pooled samples at any time point (D14 and D28). In phase II, TBS pooled samples from all batches were positive for M hyopneumoniae at D14. Implications: Nebulization of lung homogenate positive for M hyopneumoniae resulted in infection of commercial gilts with this pathogen. Therefore, the use of NEB may be a reliable M hyopneumoniae exposure method under field conditions. The information generated in this investigation broadens the understanding of this technology as an acclimation strategy.