Needle-free intramuscular jet vaccination in finishing pigs: effects on growth, carcass quality, cortisol levels, and CSF-specific neutralizing antibodies.

This study compared needle-free jet injection (NFI) with conventional needle vaccination in finishing pigs, evaluating growth performance, carcass quality, serum cortisol, macroscopic injection-site safety, and Classical Swine Fever (CSF)-specific neutralizing antibody responses. Twenty-four 3-week-old crossbred pigs were randomly assigned to receive both CSF and Foot-and-Mouth Disease (FMD) vaccines into the mid-neck muscle via either conventional needle (control) or an electromagnetic NFI device. Growth metrics, including body weight, average daily feed intake (ADFI), and feed conversion ratio (FCR), were monitored weekly. Serum cortisol was measured 30 min post-vaccination to assess acute stress. CSF antibody titers were determined at 6, 8, 12, and 14 weeks of age (0, 14, 42, and 56 days post-vaccination; dpv). Carcass traits and internal tissue integrity were assessed post-slaughter. Results showed no statistically significant differences (P > 0.05) between groups in overall growth performance, acute cortisol elevations, or CSF antibody titers. Both groups exhibited significant increases in antibody titers at 56 dpv compared to baseline (P < 0.05). Carcass characteristics were similar between the groups, although the NFI group showed a tendency toward a higher picnic cut percentage (P = 0.053). Importantly, no severe macroscopic injection-site reactions were observed, supporting acceptable macroscopic injection-site safety under the field conditions evaluated. These findings support the potential use of NFI under commercial field conditions by demonstrating comparable production outcomes, similar acute stress responses, non-inferior humoral immunity, and acceptable macroscopic injection-site safety.