A recent study by the group at Carthage (IL) Veterinary Service (CVS) has provided some insight into possible differences between the three commercial PCV2 vaccines.
Kelly Greiner, DVM, reported the findings at the CVS 18th Annual Swine Conference held Sept. 9 at Western Illinois University, Macomb. Greiner says the differences, while present, are not “statistically significant.”
The trial completed at Carthage, IL, found:
Fort Dodge Animal Health's Suvaxyn PCV2 (porcine circovirus type 2) One Dose, Intervet's Circumvent PCV and Boehringer Ingelheim's CircoFLEX all significantly decreased total mortality and improved average daily gain (ADG).
Fort Dodge's Suvaxyn PCV2 One Dose and Intervet's Circumvent PCV showed better reduction of PCV2 viremia (infection in the blood) than Boehringer Ingelheim's CircoFLEX, he says.
Furthermore, the Fort Dodge vaccine “showed a numerical trend towards better reduction of PCV2 viremia than Intervet's Circumvent PCV (two-dose) vaccine, but the results were not statistically different,” Greiner points out.
There were 1,200 pigs enrolled in the study, with six treatments of 200 pigs per treatment in a wean-to-finish barn. All pigs were between 18 and 25 days of age.
Pigs were stocked 30/pen for a stocking density of 7.5 sq. ft./pig.
The six treatment groups of pigs were color-coded as follows:
Red treatment: Suvaxyn PCV2 One-Dose given at 3 weeks of age;
Orange treatment: Suvaxyn PCV2 One-Dose given at 5 weeks of age;
Purple treatment: Suvaxyn PCV2 One-Dose given at 3 and 5 weeks of age;
Blue treatment: Boehringer Ingelheim's (BI) CircoFLEX given at 3 weeks of age;
Green treatment: Intervet Circumvent PCV given at 3 and 5 weeks of age; and
Gray treatment: Control group (sterile water) given at 3 and 5 weeks of age.
Serum samples were randomly collected from 50 pigs or 25% from each group at multiple times during the trial. Polymerase chain reaction (PCR) testing monitored viremia levels, a reflection of infection levels in the blood. All pigs were weighed at Day 0 (weaning) and just prior to marketing at Day 141-142 on test, Greiner says.
Tests for PCV2 viremia indicated that there were minimal levels of infection in all but the unvaccinated groups out to 8 weeks of age. Control pigs showed evidence of PCV2 viremia by 12 weeks of age.
“Pigs vaccinated with BI's CircoFLEX showed a higher rate of viremia (positive pigs) throughout this trial period, while the Fort Dodge and Intervet treatment groups had very, very low levels of virus in their three treatment groups,” states Greiner.
Despite these differences, when it came to total mortality, regardless of cause of death (Figure 1), mortality was low across all PCV2-vaccinated groups. The mortality rate in control pigs was 8.5%, he says.
Cull pigs were also evaluated at the end of this study, which included all pigs lighter than 200 lb. at 141 days of the study.
“Interestingly, the Fort Dodge vaccine given at 5 weeks of age had the lowest number of culls, and that was significant,” Greiner reports (Figure 2). Cull rate was less than 1% for that Fort Dodge group, compared to 3.3% for the control group.
In terms of percent marketed, the vaccinated groups all turned out fairly similar (Figure 3), averaging 95% marketed, compared to 88% marketed in the control group.
Results for the control group “were significantly lower” when it came to pounds marketed (Figure 4).
Pigs given the Fort Dodge vaccine at 3 weeks of age and the two-dose Intervet vaccine produced many more pounds of pork than the three other vaccine groups. “And as we look at all vaccinates as a whole, all groups showed significantly more pounds marketed than the control group,” he notes.
Average daily gains were not statistically different for pigs given the three vaccines tested.
Despite differences in infection rates (viremia), differences in performance (Figure 3 and Figure 4) were relatively minor for the vaccine groups, even though there were some major variations in ending weights, Greiner explains.
The herd of origin was PCV2 positive, negative for porcine reproductive and respiratory syndrome (PRRS) and positive for Mycoplasmal pneumonia. Six months prior to the trial, the herd recorded 27% mortality without vaccinating for PCV2 or mycoplasma.
Co-infections with PRRS, mycoplasma and swine influenza virus increase the risk of clinical signs of porcine circovirus-associated disease.
More Studies to Come
Results of a second study being analyzed compares performance, serology and viremia data between the Fort Dodge and Intervet vaccines administered at different ages, Greiner says.
A third trial underway compares all three PCV2 vaccines in a modified, barn-by-barn study testing 1,000 vaccinates and 200 control pigs/barn.
A fourth study attempts to duplicate the results of the first Carthage case discussed, while a fifth trial evaluates the effects of the three different commercial PCV2 vaccines on nursery pig performance, and if any of the tested vaccines have a higher incidence of adverse reactions.