Abstract
BackgroundThis study sought to evaluate the effect of sow vaccination against Porcine circovirus 2 (PCV2) on reproductive parameters during two consecutive reproductive cycles. The study was performed in a PCV2 subclinical infected breeding herd (PCV2 circulation but absence of major reproductive problems). Ninety-four pregnant sows were primo-immunized with a commercial PCV2 vaccine and ninety-seven were injected with phosphate-buffered saline at 6 and 3 weeks before the first studied farrowing, and then boosted at 2 weeks before the second one. Blood samples were taken throughout the study to assess PCV2 DNA load and antibodies. At farrowing, main reproductive parameters and piglet vitality index were registered. In addition, in those litters with more than three mummified or stillborn piglets, microscopic examination and PCV2 antigen detection in foetal myocardium was done.ResultsVaccinated sows showed significantly higher antibody levels compared to the non-vaccinated counterparts. PCV2 DNA was only detected at farrowing in 2 (4.2%) non-vaccinated sows. Vaccinated sows had 1.3 more live-born piglets per litter at the second cycle than non-vaccinated counterparts. Piglets from vaccinated sows had significantly higher (+ 12.7%) vitality score than the ones born from non-vaccinated sows. No PCV2 compatible lesions neither PCV2 antigen were detected in the tested foetal hearts.ConclusionsThe present study represents a first attempt to demonstrate that PCV2 sow vaccination may have a positive influence on prolificacy and vitality of the offspring in a subclinical infected breeding herd. However, since reproductive outcomes at farm level may be affected by a number of factors, further studies would be needed to confirm this association.
Highlights
This study sought to evaluate the effect of sow vaccination against Porcine circovirus 2 (PCV2) on reproductive parameters during two consecutive reproductive cycles
The particular affected sow was from the vaccinated group and developed severe lameness at the end of the first reproductive cycle, when it was excluded from the study
Whereas at first reproductive cycle number of stillborn piglets per litter was significantly higher in the vaccinated group, at the second period this parameter was numerically higher in the non-vaccinated one
Summary
This study sought to evaluate the effect of sow vaccination against Porcine circovirus 2 (PCV2) on reproductive parameters during two consecutive reproductive cycles. PCV2 has been shown to be involved in reproductive disorders in sows such as return-to-oestrus, late term abortions and increased number of mummified, stillborn and nonviable piglets at birth [3,4,5,6,7,8], as well as early embryo mortality [7, 9]. In this context, PCV2 can be transmitted to the embryos as soon as they get rid of the zona pellucida [10], to the foetus through the placenta [11] and to the new-born piglets by colostrum [12]. This overall situation leads to the fact that clinical and noticeable reproductive disease (PCV2-RD) attributed to PCV2, at field level, is infrequent [6, 11, 17]
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