Comparative Efficacy of PCV2 Vaccines in Piglets21 August 2015
Several commercial PCV2 vaccines are available for piglet in Europe. The objective of the present study was to compare the efficacy of two PCV2 vaccines: CIRCOVAC® (Merial, France) and a subunit vaccine, writes A. Callen et al, Merial.
Material and methods
The trial was conducted in a 900-sow farrow-to-finish farm, positive to PRRSv, M. hyo and SIV. A total of 600 piglets were weaned at 4 weeks of age and randomly allocated to vaccination with 0.5 ml of CIRCOVAC (Group N, n=291) or with 2 ml of a PCV2 subunit vaccine (Group R, n=309 ).
Pigs from the two vaccine groups were commingled both in the post-weaning and in the fattening units. They were individually weighed at weaning, placement on the fattening unit and immediately before the first delivery of pigs to the slaughterhouse.
A subsample of 15 animals per vaccination group was identified and placed in pairs of both vaccination groups in 15 different pens distributed throughout the post-weaning and fattening facilities and blood sampled at 4, 8, 11, 15, 19 and 23 weeks of age.
Sera were tested for PCV2 antibodies using two commercial ELISA kits (IgG/IgM blocking ELISA, INGENASA and indirect ELISA, BIOCHEK). Data was analyzed through a 2-way ANOVA model for group and sex factors or using Wilcoxon test within each gender stratum if not applicable.
A total of 25 piglets (4.2%) died from several causes (wasting, diarrhea, meningitis, etc.) during the post-weaning period; 20 additional pigs (3.5%) were found dead during the fattening period. Mortality rate was 7.5% from weaning to slaughter with no statistical difference between the vaccine groups.
Causes of death were not recorded in this trial. No statistical difference was observed in live weight between groups at weaning, thus validating the randomization process.
The pigs administered CIRCOVAC had higher average live weights at the end of the post-weaning period (Group N: 20.53kg vs Group R: 19.73kg, p=0.03), attributable to better growth in the nursery (Group N: +264g/day vs Group R: +252g/day, p=0.04).
There was also a numerical improvement during finishing: Group N: +58.95kg vs Group R: +58.33kg, p=0.58). At slaughter, the pigs in group N were 1.52 kg found heavier on average : Group N: 79.58kg vs Group R: 78.06kg, p=0.17. The serological results confirmed both vaccine take and a limitation of the circulation of the field virus in each group.
In the conditions of this trial, the vaccination with CIRCOVAC 0.5 ml IM in piglets at 4 week of age was shown to be significantly better during the nursery period.
No growth compensation during the fattening period was observed in the pigs vaccinated with the PCV2 subunit vaccine, leading to a numerical but not statistically significant difference at the end of fattening.
Presented at the 2015 European Symposium of Porcine Health Management