Möglichkeiten und Grenzen eines Gesundheits-Monitoring-Programmes in Ferkelerzeugerbeständen

The goal of this study was to examine the suitability of five
disease agents that are essential in swine production, in a health
monitoring program. Not only the selected disease agents and the
diagnostic methods were examined but also the sample size. Four
market trading companies from Lower Saxony and Schleswig-Holstein
provided 38 farrowing farms for the study, and sampling was done on
a quarterly basis. Fifteen blood samples were taken from sows every
time and serologically examined for Salmonella and in one quarter
only PCV2 was tested. A total of fifteen blood samples from feeder
pigs were serologically examined for Salmonella in the first and
second quarter. In the course of the following testings, instead of
blood probes 20 faecal samples were pooled to create four samples
which were bacteriologically examined. Additionally, 30 blood
probes from three growing stages were examined for antibodies
against PCV2 using Ingezim PCV IgG/IgM ELISA. Twenty nasal swabs
were pooled to create four samples that were tested for the EU and
US strains of PRRSV. Furthermore, the four pooled faecal samples
were examined for Brachyspira spp. using Multiplex-PCR, and the
probes from the first two quarters were also examined for
Campylobacter spp.. The farms were assigned into one of four
categories, 0 to 3, based on their results from the serological
examination for Salmonella and similar to those of the Salmonella
VO and QS. Based on the sow results, 10.8% of the farms were in the
category 0, 67% in the category 1 and the rest of the farms fell
into the categories 2 and 3. Feeder pigs from three farms were
placed in the category 1 and the rest were assigned the category 0.
In the following bacteriological examination, Salmonella was
identified in ten farms. The bacteriological examination method was
better in the flatdeck when compared to the serological method. The
serological examination of the sows proved to be effective for a
health monitoring program. Antibodies for PCV2 were found in the
sows in all farms, which confirms its ubiquitous distribution. No
seroconversion could be identified in the weaner-to-feeder pigs in
10 farms. Many farms began piglet vaccination during the project.
It was noted that the vaccination influenced the results of the
Ingezim ELISA in these farms and that an examination is not
necessary. This test can be well implemented in a monitoring
program in farms that do not vaccinate. However, this test also
identifies maternal antibodies and this needs to be taken into
consideration when interpreting results. B. hyodysenteriae could
not be identified in any farms. Other Brachyspira species that
occur in swine could not be identified with the exception of B.
innocens that was found in two farms. PCR appears to be a suitable
diagnostic tool for a health monitoring program. The examination
for Campylobacter spp. showed a wider distribution of C. coli, and
89.4% of the farms tested positive. C. jejuni could only be found
as a coinfection with C. coli in one farm. In four farms, no
Campylobacter sp. could be identified. In this case, PCR is also
suitable for examining faecal samples. The outcome of the PRRSV
examination showed highly differing results in every test period.
78.9 % of the farms altered their status during the project. This
infers that the sample size was inadequate in order to determine
the actual status of the farm. Moreover, a significant correlation
between vaccine strain and the PCR results was observed. The PCR
only differentiated between both genotypes but not between field
and vaccine strains. However, a differentiation is advisable for a
health monitoring program. Alternatively, the examination for
PRRSV-free nucleus farms could be restricted and simply the vaccine
status could be documented in other production units.