Comparative Evaluation of Growth Performance between Bivalent and Trivalent Vaccines Containing Porcine Circovirus Type 2 (PCV2) and Mycoplasma hyopneumoniae in a Herd with Subclinical PCV2d Infection and Enzootic Pneumonia

The present field trial compared two combined vaccines of porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae, each administered in herd with subclinical PCV2d infection and enzootic pneumonia. One vaccine was a bivalent containing PCV2a and M. hyopneumoniae and the other was a trivalent vaccine containing PCV2a and 2b (PCV2a/b), and M. hyopneumoniae. The defining difference between these two vaccines was the inclusion or absence of PCV2b antigen. A total of 480, 21day-old pigs were randomly allocated to one of four treatment groups (120 pigs per group, male = 60 and female = 60). These groups included; one-dose trivalent-vaccinated, two-dose trivalent-vaccinated, one-dose bivalent-vaccinated, and unvaccinated. The one- and two-dose trivalent vaccinated pigs exhibited significantly better growth performance when compared with those vaccinated with the bivalent vaccine. The one- and two-dose trivalent vaccinated pigs also reduced the amount of PCV2d loads in the blood and feces, and resulted in a lower M. hyopneumoniae load in the larynx when compared with one-dose bivalent vaccinated pigs. Statistical differences were not observed between the one- and two-dose trivalent-vaccinated groups in terms of growth performance, serology, amount of PCV2d loads in the blood and feces, amount of M. hyopneumoniae load in larynx, and pathological lesions. The results of the present study will provide swine practitioners and producer with comparative clinical field data to select the proper vaccine and vaccination regiment for herds suffering from subclinical PCV2d infection and enzootic pneumonia.