Field Trial Assessment of Two Commercial Vaccines Against Mycoplasma Hyopneumoniae

Abstract Background: Mycoplasma hyopneumoniae (M.hyo) is one of the most prevalent pathogens causing respiratory disorders in swine populations as well as primary agent of porcine respiratory disease complex (PRDC). The aim of this trial is to compare the efficacy of two commercial vaccines under field conditions, applied via different routes of administration, as a tool to control disease.Results: 3 groups each consisting of 440 animals, were included in this longitudinal study; one group vaccinated against M.hyo with an intradermal vaccine (group I), a second group vaccinated with an intramuscular vaccine 2940 strain (group H) and finally a third group, not vaccinated as a control (group N). All animals were individually weighed at weaning; upon entry into the fattening unit and just prior to movement to the slaughterhouse. Pigs from each group were periodically blood sampled to evaluate the immunological status against other pathogens involved in PRDC. Tracheobronchial swabs were collected from 30 pigs per treatment group during the final weighing. Slaughterhouse lung lesion evaluations were developed to assess levels of enzootic pneumonia-like lesions (EP) and pleuritis (P).Statistical evaluation of all test parameters indicated a better performance of the intradermal vaccinated group (group I):· in terms of weight (kg) just prior to movement to the slaughterhouse, (I= 97.45; H = 93.44; N = 93.05).· The number of positive tracheobronchial swabs, as well as M.hyo load detected individually (I = 36.7% positive samples with log10 Ct average value 1.48; H = 100% with log10 Ct 1.40; and N = 96.7% with log10 Ct 1.40),· EP prevalence (I = 35.1%, H = 47.0%, N = 50.5%) and· Pleurisy prevalence (I = 22.4%, H = 29.7%, N = 39.3%).In terms of the involvement of other PRDC pathogens, the serological study could lead us to think that the agents studied were present at same level in the all 3 vaccination groups.Conclusion: In this study, intradermal vaccination provided better performance than unvaccinated control group and intramuscular vaccine, in terms of weight increase (versus intramuscular group); reduction of enzootic pneumonia and pleurisy lesions, and tracheobronchial M.hyo prevalence at the end of the finishing period.