Field Trial Demonstrates Superiority of a Live Attenuated Vaccine for Integrated Control of Mycoplasmal pneumonia of Swine and Improved Production Performance in Commercial Swine Farms

A field trial was conducted on a single commercial swine farm to compare the integrated control efficacy of an inactivated vaccine and a live attenuated vaccine against mycoplasmal pneumonia of swine (MPS). Mhp exposure in the herd was confirmed by qPCR prior to trial initiation. Initially, 30 five-day-old piglets were randomly assigned to three groups (10 piglets per group): non-immunized control, inactivated vaccine, and live attenuated vaccine, for clinical safety evaluation. Based on this, another 900 five-day-old piglets, confirmed Mhp-negative by antigen detection, were randomly allocated to three separate rearing zones (300 piglets per zone), with each zone randomly assigned to one of the three treatment groups. Parameters assessed included mucosal (sIgA) and serum (IgG) antibody levels, pulmonary inflammatory cytokine (e.g., IL-1β, IL-6, TNF-α) expression, lung lesion scores, and histopathological changes, with all evaluations performed by technicians blinded to group allocation. Growth performance and economic indicators were also recorded. Both vaccines exhibited favorable safety profiles. The live attenuated vaccine significantly enhanced nasal sIgA and serum IgG levels (p ≤ 0.01), whereas the inactivated vaccine only significantly elevated serum IgG (p ≤ 0.01) but had no significant effect on sIgA (p ≥ 0.05). The live attenuated vaccine group showed the lowest lung lesion scores, as well as the mildest pulmonary inflammation and pathological damage. Meanwhile, swine in this group achieved higher average daily gain, lower mortality, and lower feed conversion ratio, with a 3-day shorter rearing period than the non-immunized group and an 11.27 CNY reduction in combined vaccination and medication cost per swine compared with the inactivated vaccine group. In conclusion, under the conditions of this single-farm trial, the live attenuated vaccine demonstrated superior efficacy in integrated MPS control and production performance improvement.