LUCRĂRI ŞTIINłIFICE MEDICINĂ VETERINARĂ VOL. XLI, 2008, TIMIŞOARA
THE CYATHOSTOMINE LARVAE POLLUTION DEGREE ON
PASTURE FROM RADIMNA VILLAGE, CARAŞ-SEVERIN COUNTY
1
1
1
1
1
S. MORARIU , GH. DĂRĂBUŞ , I. OPRESCU , NARCISA MEDERLE , M. ILIE ,
2
1
D. STEPANESCU , SILVANA MIHAILOVICI
1
Faculty of Veterinary Medicine, Timişoara, sorin.morariu@fmvt.ro;
2
DSVSA ReşiŃa, Caraş-Severin
Summary
Cyathostomines are the most widespread nematodes parasitizing horses. The
paper describes the prevalence of cyathostomine and other nematode larvae on the pasture
of Radimna village from Caraş-Severin County. In the grasses samples collected from the
pasture of Radimna village there were identified the following species of nematodes:
cyathostomines, Strongylus equinus, Strongylus edentatus, Strongylus vulgaris, digestive
strongyles of other species, and free-living nematodes, respectively. The population peaks of
L3 of cyathostomines were recorded on autumn (45.25% in October) and spring (35.71% in
May) months. The highest prevalence was recorded in free-living nematodes during the
entire study period, and the lowest prevalence was observed in S. equines and S. vulgaris
species.
Key words: cyathostomine and other nematode larvae, prevalence, pasture.
During the last 25 years of large strongyle infections as a result of
widespread use of modern anthelmintics, the clinical importance of small strongyle
infections has become underlined and these nematodes have been recognized as
an important cause of weight loss, diarrhoea and colic, poor growth, anaemia,
debilitation and rough hair coat [4, 6, 8, 9, 12, 13, 14].
Cyathostomines are ubiquitous in grazing horses and are now considered
as the major targets of equine parasite control programs. Treatment times are
based on knowledge of seasonal patterns of infection risk which include faecal egg
output, parasite development within the horse, development and survival of freeliving stages under differing conditions of climate and pasture management [5, 7,
10, 13].
In general, peaks of L3 counts on pasture occur during the late summer to
early autumn in the northern temperate climatic zone when conditions are ideal for
development and survival. L3 sharply decrease during cold winter months [1, 2, 3,
11, 14].
The objective of this study was to define the seasonal dynamics of
cyathostomine transmission patterns. The L3 levels were monitored in several
months, during October 2006 to May 2007.
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LUCRĂRI ŞTIINłIFICE MEDICINĂ VETERINARĂ VOL. XLI, 2008, TIMIŞOARA
Materials and methods
How were the grasses samples collected?
The grass samples were collected every month, from October 2006, up to
May 2007, excepting the months of December, January and February. The
samples were collected from surfaces describing a circle with a one meter
diameter, around the faeces samples. Each time, 200 g of grass were collected.
There was taken into consideration the weight of grass in the moment of being
collected and after 30 days of drying at a temperature of 27°C (dry weight). Up to
the moment of being processed, the grass samples were packed in plastic bags.
In the Parasitic Diseases Department, the collected grass was well
washed. The liquid obtained after washing was examined by Baermann method. At
the same time, the liquid obtained after washing the plastic bags was centrifuged
for 5 minutes, at 3000 rpm. The sediment was filtered through a very fine sieve
(with 25 µm mesh) and washed with tap water. The larvae remained on sieve were
suspended in 30 ml of tap water.
1/5 of the sample (6 ml) was examined in order to count the larvae. The
first 100 larvae were identified.
The calculation formula was the following:
No. L3/Kg of dry grass = [no. of larvae x 1000/dry weight of the grass (in
grams)] x 5
The pasture field was used by horses, sheep and cattle, but the number of
horses prevailed. Due to a long winter, when the pasture was covered by snow, no
grass was collected on months of December, January and February.
Results and discussions
In the Table 1, there are presented the results obtained after the
examination of the grass samples.
Table 1
The total number of nematodes larvae collected from the pasture of Radimna
village during the study.
No. of L3 on month (%):
Species
Cyathostomines
Strongylus
equinus
Oct.
Nov.
Mar.
Apr.
May
17,608
(45.25%)
434
(1.11%)
7,556
(39.08%)
222
(1.14%)
435
(12.50%)
1,277
(19.36%)
0
0
4,255
(35.71%)
213
(1.78%)
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LUCRĂRI ŞTIINłIFICE MEDICINĂ VETERINARĂ VOL. XLI, 2008, TIMIŞOARA
Strongylus
edentatus
Strongylus
vulgaris
Digestive
strongyles
(other species)
Free-living
nematodes
TOTAL
0
213
(3.23%)
0
0
2,667
(13.80%)
870
(25.00%)
1,916
(29.05%)
2,340
(19.63%)
12,828
(32.96)
8,223
(42.53%)
2,173
(62.50%)
3,190
(48.36%)
4,468
(37.49%)
38,913
19,334
3,478
6,596
11,915
652
(1.67%)
434
(1.11%)
444
(2.28%)
222
(1.14%)
6,957
(17.87%)
426
(3.57%)
213
(1.78%)
The free nematodes had an almost uniform presence, but contradictory
when favourable conditions appear: a small number on months with favourable
conditions (12,828 = 32.96%, on October 2006 and 4,468 = 37.49%, on May 2007),
and a great number on less favourable months (8,223 = 42.53%, on November
2006; 2,173 = 62.5%, on March 2007 and 3,190 = 48.36%, on April 2007). So, the
population peak was recorded on March 2007, which means and proves the fact
that these nematodes survive in winter conditions. It can be observed that the free
nematodes had the most abundant prevalence during all these months.
One can notice that L3 of cyathostomines are abundant on the pasture:
45.25% on October 2006, 39.08% on November 2006, 19.36% on April 2007 and
35.71% on May 2007. The smallest number of cyathostomines was in March, when
only 435 L3 (12.50%) were identified. So, the cyathostomines were placed on the
second place concerning their distribution.
On the third place there were L3 of different digestive strongyles, which
parasite the sheep and the cattle, and which had relatively constant values, during
the months under consideration (minimum 13.80%, on November 2006 and
maximum 29.05%, on April 2007). The percentage decrease from May 2007 after
the peak from April 2007 can be explained as follows: a) the sheep went out for
grazing earlier, because the good conditions during winter and spring; b) the
phenomenon of “peri-parturient rise” or “spring rise”, which led to an abundant
pollution of pasture, at the beginning of the spring; c) the horses went out for
grazing, relatively, later.
The other three identified species S. equinus, S. edentatus and S. vulgaris
had a law quantitative presence, which varied between 1.11% and 1.78%, for S.
equinus and S. vulgaris, and between 1.67% and 3.57%, for S. edentatus,
respectively. On March 2007, the three species were not identified, and during April
only S. edentatus was registered out of these three species of large strongyles.
The graphics 1 to 5, show the quantitative presence of the categories
identified during the study period.
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LUCRĂRI ŞTIINłIFICE MEDICINĂ VETERINARĂ VOL. XLI, 2008, TIMIŞOARA
18000
16000
October
17608
14000
12828
12000
10000
8000
6957
6000
4000
2000
0
434
Cyathostomines
S. equinus
652
S. edentatus
434
S. vulgaris
Dig. Strongyles
Free nematodes
Graphic 1. L3 dynamics on pasture on October 2006.
9000
8000
November
8223
7556
7000
6000
5000
4000
2667
3000
2000
1000
0
222
Cyathostomines
S. equinus
444
S. edentatus
222
S. vulgaris
Dig. Strongyles
Free nematodes
Graphic 2. L3 dynamics on pasture on November 2006.
2500
March
2173
2000
1500
870
1000
435
500
0
0
Cyathostomines
S. equinus
0
0
S. edentatus
S. vulgaris
Dig. Strongyles
Free nematodes
Graphic 3. L3 dynamics on pasture on March 2007.
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LUCRĂRI ŞTIINłIFICE MEDICINĂ VETERINARĂ VOL. XLI, 2008, TIMIŞOARA
3500
3190
April
3000
2500
1916
2000
1277
1500
1000
500
0
0
Cyathostomines
S. equinus
213
S. edentatus
0
S. vulgaris
Dig. Strongyles
Free nematodes
Graphic 4. L3 dynamics on pasture on April 2007.
4500
4225
May
4468
4000
3500
3000
2340
2500
2000
1500
1000
500
213
426
213
0
Cyathostomines
S. equinus
S. edentatus
S. vulgaris
Dig. Strongyles
Free nematodes
Graphic 5. L3 dynamics on pasture on May 2007.
As far as the dynamics of cyathostomine population we concerned
(Graphic 6) we can notice a seasonable distribution of L3, on pasture. On October
and November 2006, when there was enough humidity and the day-time
temperatures varied between 4 - 18°C, the L3 of cyathostomines were abundant.
On winter months, when the temperature went down to 0°C and more, the larvae
did not survive in such a manner; this was proved by the fact that, on March 2007,
only a relatively small number of L3 (12.5%) were recovered.
As the weather got warmer and the horses went out for grazing, a constant
increase of the pollution degree on pasture was noticed: 19.36% (1,277 L3/kg dry
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LUCRĂRI ŞTIINłIFICE MEDICINĂ VETERINARĂ VOL. XLI, 2008, TIMIŞOARA
grass), on April, at temperatures over 15°C, and 35.71% (4,255 L3), on May, at
day-time temperatures over 23°C.
435
1277
7556
4255
17608
October
November
March
April
Graphic 6. Cyathostomine L3 dynamics on pasture in
October 2006 – May 2007.
Consequently, we can notice that the resistance of L3 of cyathostomines,
during winter, is lower, which makes us consider the pastures as being not so
infective, during early spring time. On the contrary, during autumn and late spring
time, L3 of cyathostomines develop correspondingly, reaching population peaks.
As a matter of fact, it was reported that these L3 develop optimally when the
temperature varies between 10 - 33°C and the excessive humidity negatively
influence their development, although it is necessary for evolution [1, 11].
Conclusions
In the grasses samples collected from the pasture of Radimna village there
were identified the following species of nematodes: cyathostomines, Strongylus
equinus, Strongylus edentatus, Strongylus vulgaris, digestive strongyles, and freeliving nematodes, respectively.
L3 of cyathostomines do not survive efficiently during winter, on pastures
located in Radimna area, but they rich a relatively high number on March: 435 out
of a total of 3,478 collected larvae.
The population peaks of L3 of cyathostomines on pastures from Radimna
were recorded on autumn and spring months.
L3 of cyathostomines develop easier and survive longer when the humidity
is not excessive and the temperatures are between 10 - 25°C.
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