The aurochs is a greatest wild mammal living in Europe. The investigation was passed on 10 aurochses both the sex and different age. In clinical examination was observed low gain in weigh at young animals, fall of the form and progressive weediness at full grown animals. In coprological examination was find great infection of gastro-intestinal nematodes (Trichostrongylidae and Trichuris sp.) in all aurochses and infection of lung nematodes (Dictyocaulus sp.). To the treatment was produced granulated fodder contain 0,6% ivermectin. After 10 days from the ivermectin application in no sample of the faeces one did not find eggs of gastro-intestinal nematodes and did not find larvas of lung nematodes. After 60 days from the ivermectin application was find single eggs of gastro-intestinal nematodes in seven sample. Single larvas of lung nematodes (Dictyocaulus sp.) was find in one sample.

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