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being present in the environment and subsequently cause higher liver
condemnation rates in summer and early autumn. 40,65,85,86
Frequent cleaning of the pens, preferably after each round, is indis-
pensable to destroy or reduce the amount of eggs in the environment.
Clearly, the presence of rough and uneven surfaces would provide a good
microenvironment for egg development and have an impact on the effi-
ciency of cleaning protocols. Joachim et al. 3 indicated that in older pens,
the prevalence of Ascaris infections was significantly higher (63.0%) than in
the new pens (27.9%). Moreover, Nilsson (1982) 40 found high numbers of
eggs (up to 3,000 eggs per gram) in the crevices of the floor between the
slatted dung area and the resting area of the pen. Approximately half of
these eggs appeared to be embryonated. In a study by Beloeil et al. 69 31%
of the farms surveyed had residual dung in the fattening pens when
restocking them with new fattening pigs, a practice favoring the trans-
mission of A. suum eggs. Even though careful cleaning of the pens with
high pressure water will remove most of the residual dung, it seems
ineffective to completely remove all the infective eggs. 40 Although the use
of disinfectants is effective against bacteria, most of them are rather inef-
fective against A. suum eggs. 87 e 89 Instead, steam cleaning 90 and drying of
the pens is a highly recommended management practice for killing
roundworm eggs. These are, however, hard to comply with in practice.
Looking to the future, the percentage of Ascaris -favorable production
systems is expected to rise. Increased consumer awareness induces a shift
from the industrial husbandry, with its high use of medication, feed
additives, and questionable animal welfare, towards a more organic
production system where pigs enjoy improved living comforts like
bedding materials and outdoor runs and where prophylactic use of
medication to prevent disease is not allowed. In addition, forthcoming
implementation of new regulations for increased pig well-being will
provide more parasite-friendly environments as well. In Denmark, for
example, sprinkler systems should be placed in the pens of growing pigs
and sows to accommodate a daily shower. Moreover, sows should not be
tethered and should be housed in groups in enriched environments
(bedding, wallowing) for part of the gestation. 78,91 As a result, the number
of eggs surviving in the pens will increase and with it the prevalence of
Ascaris and other pig parasites. 5 Good diagnostic assessments will be
necessary to evaluate how these changes in farm management will affect
parasite epidemiology.
CONCLUDING REMARKS
In summary, veterinarians that are assigned the task of developing an
effective treatment plan for a specific facility are advised to first evaluate
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