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Waruiru RM Thamsborg SM Nansen P Kyvsgaard NC Bogh HO Munyua WK Gathuma JM 《Tropical animal health and production》2001,33(3):173-187
The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round. 相似文献
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This study was carried out to obtain basic information on the transmission of Oesophagostomum dentatum and Hyostrongylus rubidus in outdoor reared pigs in Denmark. Eighteen 10 weeks old worm-free pigs were allocated into 3 groups of 6 pigs each. In May, all pigs were turned out on the same parasitologi-cally naive pasture, and after 2 weeks the pigs in groups 2 and 3 were experimentally infected with 10,800 O. dentatum and 8,700 H. rubidus infective larvae, respectively. Pigs in group 1 served as non-infected controls. All pigs were reared together on the experimental pasture for further 134 days until slaughter in October. Strongyle egg counts, differentiation of infective larvae at species level, serum pepsinogen, and herbage larval infectivity were monitored at regular intervals throughout. Both strongyle species established in the originally parasite-free pigs (group 1) and cross infections were established in group 2 and 3. The pigs were exposed to steadily increasing herbage infectivity of both species of strongyles. At the end of the experiment, geometric mean worm burdens of O. dentatum in groups 1,2 and 3 were 1202, 6136 and 1431 respectively, the burden in group 2 being significantly higher (p<0.05) than that of the 2 other groups. The geometric mean worm burdens of H. rubidus in groups 1, 2 and 3 were 4907, 3679 and 5246 respectively, showing no significant differences between groups. 相似文献
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Magwisha HB Kassuku AA Kyvsgaard NC Permin A 《Tropical animal health and production》2002,34(3):205-214
Matched samples of 100 chickens of each of growers and adult rural free-range chickens in Morogoro, Tanzania, were purchased from the beginning to the end of the long rainy season. At necropsy, the trachea, the gastrointestinal tract and the oviduct were examined for helminth infections. The helminth species isolated comprised 18 nematodes and 8 cestodes but no trematodes. Tetrameres fissispina is a new record in Tanzania. All the chickens harboured at least three different helminth species. Growers contained 4–14 and adults 3–12 helminth species. The number of species isolated per chicken increased as the rainy season advanced. The prevalence of the following species were significantly higher in growers than in adults (p<0.05); Ascaridia galli (69% of growers, 29% of adults); Syngamus trachea (14%, 3%); Tetrameres americana (94%, 82%); Trichostrongylus tenuis (43%, 7%); Choanotaenia infundibulum (15%, 6%); Davainea proglottina (9%, 2%); and Raillietina tetragona (36%, 21%). Allodapa suctoria (3%, 20%) and Capillaria annulata (1%, 10%) had a significantly lower prevalence in growers than in adults (p<0.05). There were significantly higher worm burdens (p<0.05) in growers than in adults for A. galli, Capillaria caudinflata, R. tetragona, S. trachea, T. americana, T. fissispina and T. tenuis. Conversely, A. suctoria and C. annulata showed significantly higher worm burdens in adults (p<0.05). The sex of the chickens influenced the burdens of Heterakis brevispiculum (p<0.05). There was an interaction effect such that growing males and adult females had statistically higher (p<0.05) burdens of T. tenuis and A. suctoria, respectively. 相似文献
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