Palestras e Artigos Científicos - Embrapa Suínos e Aves

XIII Congresso Brasileiro de Veterinários Especialistas em Suínos – ABRAVES
16 a 19 de outubro de 2007 - Florianópolis, SC
summarized in Table 5. The graphic repartition of the herds in post weaning and in the
finishing is shown in Figure 3 and 4 respectively. Basic mortality is the residual mortality
including all different accidental and anecdotal causes that are usual for a given farm
without particular identified disorders. The predictive mortality reduction (PMR) is the
answer to the question: “What reduction of mortality over the basic mortality may be
expected after vaccination?” Strong positive linear correlations were found between
reduction of mortality and mortality before vaccination in the post-weaning and the
finishing age groups. This means that the higher the mortality linked to PCV2 before
vaccination, the higher the expected reduction of mortality. The lower R² found in the
suckling phase, indicates that, for this sample of farms, the linear model was less
adequate.
In this German study, the results were obtained in a very large number of herds (n =
233). Mortality was significantly reduced during vaccination in the three stages of growth,
i.e. minus 2.9%, 4.8% and 2.6% in the suckling, post-weaning and finishing stages,
respectively. On average, the farms returned to a close to “normal” situation (18) with postvaccination
mortality rates of 11.0%, 3.1% and 3.0% in the three groups of age,
respectively. These findings show that pigs born from vaccinated sows are protected
against the deleterious impact of PCV2 during their whole life span. In addition, the
improvement in the suckling phase fits with field observations by veterinarians that piglets
born from vaccinated sows appear more vigorous and healthy. This correlates too with the
results of the preliminary study on reproduction parameters showing a strong trend of
increase in the number of weaned pigs per sow per year.
Field Results in Canada
Canada as well as the United states have recently suffered from acute PMWS
outbreaks (11). Due to the emergency of the situation, CIRCOVAC was introduced in
Canada in April 2006 using a Special Import Permit. At the end of 2006, the first
preliminary efficacy results were collected using a phone survey (19) and an evaluation of
the mortality after about 6-month use of CIRCOVAC were obtained for 77 farms
representing 51,050 vaccinated sows and approximately 500,000 pigs. Weaning–toslaughter
mortality rates were often expressed as a range with a maximum (max) and a
minimum (min) values for mortality before and during vaccination. This led to calculate min
and max means and confidence intervals for the periods before and during vaccination
(Figure 5). Although these very preliminary results were obtained during a period in which
pigs born from vaccinated and non-vaccinated sows were still both present in the farms a
significant decrease of mortality and a recovery to “close-to-normal” rates for commercial
farms was seen. The regression between mortality before vaccination and the Delta%
decrease of mortality was applied. The R² found was 0.76 and the regression line equation
was: Y = 1.05 X + 5.12. The basic weaning to slaughter mortality was on average 5.12%
and the approximated Predictive mortality reduction found was then 95% above the basic
mortality. These results are in accordance with what was found in the studies run both in
France and Germany.
Conclusions
CIRCOVAC® used in gilts and sows will increase, homogenize and improve specific
maternal immunity to PCV2. Transfer of passive immunity from sow to piglet is very
efficacious, provided colostrum intake is sufficient. CIRCOVAC® vaccination will reduce
potential PCV2 shedding by the sows and the newborn piglets, thereby reducing the
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