Epidemiological Investigation Of Sheep Helminth Infections And Comparative Anthelmintic Studies In Wushen Area

Wushen County is one of the main areas of animal husbandry in Inner Mongolia Antonomous Region, and Ordos merino sheep is one of the main livestock in this County. The wool quality and mutton performance had reached the advanced level and approached or attained standards of Australian merino sheep. Because of the delayed preventive measures of parasitic diseases, the livestock performance and the yield and quality of livestock products had been lowered.In order to investigate the prevalence of main helminthiasis of naturally grazing sheep in Wushen county and supply a practical deworming program for local herdsmen, epidemiological investigations of helminthiasis and comparative anthelmintic studies were carried out in three different periods according to pastures of different climatic conditions and breeding modes from March in 2009 to March in 2010. Feacal samples were taken from the rectums of 900 sheep (300 sheep each time) selected randomly from 6 different sampling points, and the eggs were collected by floating method and centrifugal sedimentation method, then identified by optical microscope based on micro characteristics and counted by McMaster's method. Meanwhile, 60 sheep intensely infected with helminth were allocated into 6 groups of 10 animals in each, and carried out the comparative deworming study of different anthelmintics. The results showed that a high prevalence of sheep helminthiasis was existed in Wushen, and characterized by mixed infection, which were closely related to the local pasture types, climatic conditions, breeding modes and the medication history. The average infection rates of the investigations were 80.7%, 73% and 98%,respectively, and predominant helminthes were Haemonchus contortus and Nematodirus sp., and the infection rates of the first investigations were 67.3% and 60.0%. Besides, eggs of Coccidia,Trematode and Cestode of helminth were also found. 15 species of parasites were found by necropsyin belonged to 13 genera, 9 families, 4 orders, 3 classes and 2 phyla, including11 species of nematodes, 2 species of trematodes and 2 species of cestodes. According to the identification of morphological characteristics, they were Nematodirus oiratianus,Nematodirus ?longispiculata,Chabertia ovina,Haemonchus contortus,Ostertagia circumcincta,Bunostomum trigonocephalum,Trichostrongylus colubriformis,Oesophagostomum asperum,Oesophagostomum columbianum,Dictyocaulus filaria,Trichocephalus ovis,Fasciola hepatica,Eurytrema pancreaticum,Moniezia expansa and Helictometra giardi,respectively. In deworming experiment, the insecticide rate of the ivermectin following subcutaneous injection was 100%, while the albendazole with recommended dose had little effect on helminthes. The primary image collections of sheep helminth eggs were established and the characteristics of sheep helminth eggs were comparatively analyzed.In conclusion, the infection rates and infection intensities of the sheep heilminthes were relatively high in Wushen county and characterized by mixed infection with variety of helminthes. The anthelmintic effect of the ivermectin injection possesses strong anti-nematodes activities, while the albendazole had essentially no effect on the helminthes in this area.