Íslenskar landbúnaðarrannsóknir - 01.09.1974, Side 19

SHEEP PARASITES IN ICELAND 17
The most common drenching procedure is
to give all the sheep anthelmintica once a
year, either during the winter or in the spring
before lambing. Several farmers give some
or all of their sheep anthelmintica twice a
year, mainly in the early winter and in the
spring and others give anthelmintica seldom
or never.
Most of the information above is from an
unpublished paper (Richter).
In order to find the optimal time for this
treatment, different groups of sheep were
given thiabendazole at different times and
the effect on the number of nematode eggs
and larvae observed.
The effect on the eggs of „other strongy-
les" can be seen in Fig. 12 and 13, and a
'hypothesis based on these results and the
results in Fig. 5 is illustrated in Fig. 14.
After administration of thiabendazole, no
eggs were found in faeces for some time. The
length of the time most likely depends upon
the magnitude of infection in the surroun-
dings. The administration of thiabendazole in
the beginning of winter has an effect at least
until June and eggs do not begin to reappear
in faeces in significant numbers until the be-
ginning of April. This indicates that infection
during the winter has been minimal. The
effects of administration in the spring can
also be seen until June, but in this case the
first eggs reappear in faeces only three weeks
after the drug is given, which means that the
sheep have begun to acquire infection soon
after treatment.
The effect of thiabendazole on Nemato-
dirus spp. seems to be similar to the effect
on „other strongyles" but the scarcity of eggs
makes it difficult to evaluate.
The effect of thiabendazole on Muetterius
capillaris can be seen in Fíg. 9 and 10. The
number of larvae falls in most cases to zero
but the effect is short-lived because within 3
weeks the number of larvae has reached its
original magnitude. In this case reinfection
as the cause can be ruled out.
The effect of thiabendazole on Dictyocau-
lus filaria can be seen in Fig. 10 and 11. The
scarcity of larvae make it difficult to interpret
the results, but it seems likely that there is
some effect.
Considering the results of this rather limi-
ted study, the author feels that there is a
definite advantage in early winter rather
than spring drenching. The effect of both
drenchings on the magnitude of nematode
burden in the spring seems to be similar, but
the advantage of early winter treatment is
that the sheep are for the most part free of
gastrointestinal nematodes during the winter.
Drenching with thiabendazole in the
spring after it has been administered in the
early winter seems to provide a negligible
advantage over the single early winter dren-
ching and consequently appears to be uneco-
nomical, estimated by the worm egg counts.
CONSISTENCY OF FAECES
The faecal consistency was noted as: 1 =
normal pelleted, 2=soft pelleted, 3=paste
and 4=liquid or semiliquid.
From birth to 2—3 weeks of age the
faeces of lambs was yellowish with the con-
sistency of 3- Coccidiasis could be one of the
reasons for this soft consistency. From 2—3
week to 14/2 months the faeces became nor-
mal in colour and the consistency was almost
without exception 1. At the same time of
the year the faecal consistency of the older
sheep was 2—3 (Fig. 15). From the age of
IV2—4 months the faecal consistency was
not recorded.
Fig. 15 shows the consistency of the faeces
of sheep 4 months of age and older.