Íslenskar landbúnaðarrannsóknir - 01.09.1974, Síða 9

SHEEP PARASITES IN ICELAND 7
the housing of the sheep from mid-November
and the related changes in diet etc., could
have some influence.
During the second year of life the sheep
show a spring and early winter increase, but
to a much smaller extent than with the lambs.
This trend can be detected in adult sheep as
well.
A hypothesis on the variation in number
of ovocysts depending on the age of sheep
and time of year is illustrated in Fig. 16.
MONIEZIA EXPANSA
The saturated sodium chloride solution used
in the McMaster technique is not always
reliable for detecting Moniezia eggs. It can
therefore be assumed that Moniezia eggs
occur more frequently in faecal samples than
the observations show. Moniezia eggs were
not counted but only noted.
The following observations were made:
No Moniezia eggs were found in the faeces
of lambs under W2 months of age (Group
X). Studies were not made on lambs of IV2
—4 months old, because they were on the
mountain pasmres during that time. In the
age group 4—7 months (Group IV and V),
Moniezia eggs were found most frequently
(approx. 67% of the lambs). In the age
group 6V2 months to\V2. years (Group I and
II) Moniezia eggs were found Iess frequently
(approx. 50% of the sheep). In the age group
3 years and older (Group I and II) Moniezia
eggs were found less frequently (approx.
25% of the sheep).
It is obvious that the older sheep are more
resistent to Moniezia expansa than the young-
er ones. Positive observations were so few,
that it is not possible to detect any variation
in the frequency of occurrence of Moniezia
eggs in relation to the time of year.
A hypothesis on the variation in the num-
ber of sheep carrying Moniezia expansa in
relation to the age of the sheep is illustrated
in Fig. 16.
GASTROINTESTINAL NEMATODES
When nematode eggs were counted, they
were separated into three types:
Trichuris ovis eggs: A single egg was
found in the whole smdy and it will not be
discussed further.
Nematodirus eggs: Eggs of N.filicollis and
N.spathiger.
Other strongyle eggs: No further differen-
tiation was made and therefore the eggs could
have been from any of the following 10
species already observed in Iceland: Buno-
stomum trigonocephalum, Chabertia ovina,
Cooperia oncophora, Oesophagostomum
venulosum, Ostertagia circumcincta, O.trifur-
cata, Teladorsagia davtiani, Trichostrongylus
axei, T.capricola and T.vitrinus.
„Other strongyles"
In the spring of 1973 the number of eggs
in the faeces of young lambs (Group X) was
recorded. The results are presented in Fig. 3.
The youngest lamb in which eggs were
found was 36 days old and all observations
made on faeces of lambs older than 36 days
showed the presence of eggs. This indicates
1500-
Egg» prg
foeces
r. Six lambs;faecal
§ samples taken tvo
g or more times.
x Six lombs.faecal
samplcs takenonce.
1000-
500-
□ A □
0 •-----• , xflAém»»X i )épr\ m-------.------.—
10 15 20 25 30 35 40 45
Age of lambs in days
Fig. 3. Eggs of „other strongyles" in faeces of
young lambs (Group X).