Comparative growth performance of 3 types of combination vaccines containing porcine circovirus 2 and under field conditions.

The objective of this field trial was to compare the effect of 3 different types of combination vaccines on growth performance in pigs under field conditions. The vaccines compared were: a trivalent vaccine containing porcine circovirus type 2a and 2b (PCV-2a/b); and a mixable bivalent vaccine containing PCV-2a and and a ready-to-use bivalent vaccine containing PCV-2a and . Two farms were selected on the basis of their history of subclinical PCV-2d infection and enzootic pneumonia. A total of 120 pigs on each farm was randomly divided into 4 groups of 30 pigs each. The trivalent-vaccinated group from both farms outperformed each bivalent-vaccinated group in terms of growth performance. Growth performance was significantly improved during the fattening period (70 to 175 d of age) in the mixable bivalent-vaccinated group compared with the ready-to-use bivalent-vaccinated group on 1 farm. The trivalent-vaccinated group elicited higher levels of neutralizing antibodies and interferon-γ secreting cells (IFN-γ-SC) against PCV-2d, while simultaneously decreasing the levels of PCV-2d load in blood when compared with the mixable and ready-to-use bivalent-vaccinated groups. The trivalent-vaccinated group also elicited higher levels of IFN-γ-SC against and lower levels of load in the larynx when compared with the mixable and ready-to-use bivalent-vaccinated groups. The results of the present study demonstrated that a trivalent vaccine containing PCV-2a/b and resulted in a more productive parameter, higher immune responses, and less blood-viral and mycoplasmal larynx-loads when compared with the mixable and ready-to-use bivalent vaccines despite the presence of ongoing subclinical PCV-2d infection and enzootic pneumonia on the farms.